Quartz crystal unit, quartz crystal oscillator and electronic apparatus
10284143 ยท 2019-05-07
Assignee
Inventors
Cpc classification
Y10T29/49133
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
H03B5/04
ELECTRICITY
Y10T29/42
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
Y10T29/49005
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
Y10T29/4908
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
Y10T29/49128
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
H03H2003/026
ELECTRICITY
Y10T29/49135
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
H03H3/02
ELECTRICITY
International classification
H03B5/04
ELECTRICITY
Abstract
In a quartz crystal unit, the unit comprising a quartz crystal tuning fork resonator having a quartz crystal tuning fork base, and first and second quartz crystal tuning fork tines, each of the first and second quartz crystal tuning fork tines having a first vibrational portion including a first width and a second vibrational portion including a second width greater than the first width, at least one groove being formed in at least one of opposite main surfaces of the first vibrational portion of each quartz crystal tuning fork tine, the first width of the first vibrational portion of each quartz crystal tuning fork tine being greater than 0.03 mm and less than 0.075 mm and the second width of the second vibrational portion of each quartz crystal tuning fork tine being greater than 0.04 mm and less than 0.23 mm.
Claims
1. A quartz crystal unit comprising: a case; a quartz crystal tuning fork resonator; and a lid; wherein the quartz crystal tuning fork resonator has a quartz crystal tuning fork base, and first and second quartz crystal tuning fork tines connected to the quartz crystal tuning fork base, each of the first and second quartz crystal tuning fork tines comprising a plurality of vibrational portions having a first vibrational portion including a first width, and a second vibrational portion including a second width greater than the first width, the first vibrational portion of each of the first and second quartz crystal tuning fork tines having a first main surface and a second main surface opposite the first main surface; wherein at least one groove is formed in at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines; and wherein the first width of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.03 mm and less than 0.075 mm and the second width of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.04 mm and less than 0.23 mm.
2. A quartz crystal unit according to claim 1; wherein the second vibrational portion of each of the first and second quartz crystal tuning fork tines has a second length; and wherein the second length of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.2 mm and less than 0.7 mm.
3. A quartz crystal unit according to claim 2; wherein each of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines has a central linear portion; wherein the at least one groove comprises a groove formed in the central linear portion of at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines so that a width W.sub.2 of the groove formed in the central linear portion of the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is less than 0.07 mm, a first distance in the width direction of the groove measured from a first outer edge of the groove to a first outer edge of the corresponding one of the first and second quartz crystal tuning fork tines being defined by W.sub.1 and a second distance in the width direction of the groove measured from a second outer edge opposite the first outer edge of the groove to a second outer edge opposite the first outer edge of the corresponding one of the first and second quartz crystal tuning fork tines being defined by W.sub.3, and so that each of the first distance W.sub.1 and the second distance W.sub.3 is less than 0.015 mm; wherein the quartz crystal tuning fork base has a length; wherein the length of the quartz crystal tuning fork base is less than 0.5 mm; wherein the quartz crystal tuning fork resonator has an overall length; and wherein the overall length of the quartz crystal tuning fork resonator is less than 2.18 mm.
4. A quartz crystal unit according to claim 3; wherein the overall length of the quartz crystal tuning fork resonator is within a range of 0.8 mm to 2 mm; wherein the width W.sub.2 of the groove formed in the central linear portion of the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.015 mm and less than 0.052 mm and a length of the groove formed in the central linear portion of the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is within a range of 0.32 mm to 0.68 mm; wherein each of the first distance W.sub.1 and the second distance W.sub.3 is greater than 0.004 mm and less than 0.015 mm; wherein the quartz crystal tuning fork base has the length within a range of 0.12 mm to 0.255 mm, and a first base portion including a first length, a second base portion including a second length less than or equal to the first length and two cut portions formed between the first and second base portions, the first length of the first base portion of the quartz crystal tuning fork base being within a range of 0.02 mm to 0.13 mm; wherein at least one frame portion protrudes from the second base portion of the quartz crystal tuning fork base so that the at least one frame portion extends in a common direction with the first and second quartz crystal tuning fork tines outside the first and second quartz crystal tuning fork tines, and so that a length of the at least one frame portion is greater than 0.25 mm and less than 0.85 mm and a width of the at least one frame portion is less than or equal to the first width of the first vibrational portion of each of the first and second quartz crystal tuning fork tines; wherein the case has a mounting portion; wherein the at least one frame portion is mounted on the mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
5. A quartz crystal unit according to claim 3; wherein at least one frame portion protrudes from the quartz crystal tuning fork base; wherein the width W.sub.2 of the groove formed in the central linear portion of the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than each of the first distance W.sub.1 and the second distance W.sub.3 and is greater than 0.015 mm and less than 0.052 mm; wherein each of the first distance W.sub.1 and the second distance W.sub.3 is greater than 0.004 mm and less than 0.015 mm; wherein the quartz crystal tuning fork base has a first base portion including a first width W.sub.5 and a first length, a second base portion including a second width W.sub.6 greater than the first width W.sub.5 and a second length less than or equal to the first length, and two cut portions formed between the first and second base portions, each of the first and second quartz crystal tuning fork tines being connected to the first base portion of the quartz crystal tuning fork base, the second base portion of the quartz crystal tuning fork base having a first side surface and a second side surface opposite the first side surface; wherein the at least one frame portion comprises first and second frame portions each having a side surface; wherein the side surface of the first frame portion is connected to the first side surface of the second base portion of the quartz crystal tuning fork base and the side surface of the second frame portion is connected to the second side surface of the second base portion of the quartz crystal tuning fork base so that the first and second frame portions extend in a common direction with the the first and second quartz crystal tuning fork tines outside the first and second quartz crystal tuning fork tines, each of the first and second frame portions having a width and a length; and wherein the width of each of the first and second frame portions is less than or equal to the first width of the first vibrational portion of each of the first and second quartz crystal tuning fork tines.
6. A quartz crystal unit according to claim 5; wherein the first width W.sub.5 of the first base portion of the quartz crystal tuning fork base is within a range of 0.25 mm to 0.38 mm and the first. length of the first base portion of the quartz crystal tuning fork base is within a range of 0.025 mm to 0.13 mm; wherein the second width W.sub.6 of the second base portion of the quartz crystal tuning fork base is within a range of 0.25 mm to 0.52 mm and the second length of the second base portion of the quartz crystal tuning fork base is within a range of 0.02 mm to 0.072 mm; wherein the side surface of the first frame portion is connected to the first side surface of the second base portion of the quartz crystal tuning fork base and the side surface of the second frame portion is connected to the second side surface of the second base portion of the quartz crystal tuning fork base so that the second base portion of the quartz crystal tuning fork base has a concave shape or a U-shape with the first and second frame portions, and so that the width of each of the first and second frame portions is within a range of 0.02 mm to 0.055 mm and the length of each of the first and second frame portions is within a range of 0.25 mm to 0.85 mm; wherein the second vibrational portion of each of the first and second quartz crystal tuning fork tines comprises a plurality of portions having a first portion including a third width and a third length, and a second portion including a fourth width greater than the third width and a fourth length greater than the third length; wherein the first portion of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is formed between the second portion of the second vibrational portion of the corresponding one of the first and second quartz crystal tuning fork tines and the first vibrational portion of the corresponding one of the first and second quartz crystal tuning fork tines; wherein the third width of the first portion of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.04 mm and less than 0.15 mm and the fourth width of the second portion of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.15 mm and less than 0.23 mm; and wherein the third length of the first portion of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.03 mm and less than 0.15 mm and the fourth length of the second portion of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.18 mm and less than 0.45 mm.
7. A quartz crystal unit according to claim 3; wherein the quartz crystal tuning fork base has a first base portion including a first length and a first width W.sub.5, a second base portion including a second length less than the first length and a second width W.sub.6 greater than the first width W.sub.5, and a third base portion including a third length and a third width less than each of the first and second widths, the third base portion being formed between the first and second base portions, the second base portion being connected to the first base portion through the third base portion, each of the first and second quartz crystal tuning fork tines being connected to the first base portion of the quartz crystal tuning fork base, the third length of the third base portion of the quartz crystal tuning fork base being within a range of 0.012 mm to 0.055 mm and the third width of the third base portion of the quartz crystal tuning fork base being within a range of 0.04 mm to 0.125 mm; wherein the second vibrational portion of each of the first and second quartz crystal tuning fork tines comprises a plurality of portions having a first portion including a third width and a third length, and a second portion including a fourth width greater than the third width and a fourth length greater than the third length; wherein the first portion of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is formed between the second portion of the second vibrational portion of the corresponding one of the first and second quartz crystal tuning fork tines and the first vibrational portion of the corresponding one of the first and second quartz crystal tuning fork tines so that the third width of the first portion of the second vibrational portion is greater than 0.04 mm and less than 0.15 mm and the fourth width of the second portion of the second vibrational portion is greater than 0.15 mm and less than 0.23 mm, and so that the third length of the first portion of the second vibrational portion is greater than 0.03 mm and less than 0.15 mm and the fourth length of the second portion of the second vibrational portion is greater than 0.16 mm and less than 0.49 mm; wherein a first frame portion is connected to the second base portion of the quartz crystal tuning fork base and a second frame portion is connected to the second base portion of the quartz crystal tuning fork base so that the second base portion of the quartz crystal tuning fork base has a concave shape or a U-shape with the first and second frame portions, each of the first and second frame portions having a width and a length; wherein the width of each of the first and second frame portions is less than or equal to the first width of the first vibrational portion of each of the first and second quartz crystal tuning fork tines and is within a range of 0.02 mm to 0.055 mm, and the length of each of the first and second frame portions is within a range of 0.25 mm to 0.85 mm; wherein the case has first and second mounting portions; wherein the first frame portion is mounted on the first mounting portion of the case and the second frame portion is mounted on the second mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
8. A quartz crystal unit according to claim 3; wherein the first vibrational portion of each of the first and second quartz crystal tuning fork tines has a first length; wherein the second length of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is less than the first length of the first vibrational portion of the corresponding one of the first and second quartz crystal tuning fork tines; wherein the quartz crystal tuning fork base has a first base portion, a second base portion including a first portion and a second portion and a cut portion formed between the first base portion and the first portion of the second base portion, each of the first and second quartz crystal tuning fork tines being connected to the first base portion of the quartz crystal tuning fork base; wherein a width of the first base portion of the quartz crystal tuning fork base is within a range of 0.27 mm to 0.35 mm and a length of the first base portion of the quartz crystal tuning fork base is within a range of 0.025 mm to 0.13 mm; wherein each of the first and second portions of the second base portion of the quartz crystal tuning folk base has a width and a side surface, the side surface of the first portion of the second base portion being connected to the side surface of the second portion of the second base portion; wherein the width of the first portion of the second base portion of the quartz crystal tuning fork base is less than the width of the first base portion of the quartz crystal tuning fork base and is within a range of 0.18 mm to 0.285 mm, and the width of the second portion of the second base portion of the quartz crystal tuning fork base is within a range of 0.035 mm to 0.125 mm; wherein the case has first and second mounting portions; wherein the first portion of the second base portion of the quartz crystal tuning fork base is mounted on the first mounting portion of the case and the second portion of the second base portion of the quartz crystal tuning fork base is mounted on the second mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
9. A quartz crystal unit according to claim 1; wherein the quartz crystal tuning fork resonator has an overall length; wherein the overall length of the quartz crystal tuning fork resonator is less than 2.18 mm; wherein the quartz crystal tuning fork base has a length; wherein the length of the quartz crystal tuning fork base is less than 0.5 mm; wherein a width of the at least one groove formed in the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than a distance in the width direction of the at least one groove measured from an outer edge of the at least one groove to an outer edge of the corresponding one of the first and second quartz crystal tuning fork tines and less than 0.07 mm; and wherein the distance in the width direction of the at least one groove measured from the outer edge of the at least one groove to the outer edge of the corresponding one of the first and second quartz crystal tuning fork tines is less than 0.015 mm.
10. A quartz crystal unit according to claim 9; wherein the overall length of the quartz crystal tuning fork resonator is within a range of 0.8 mm to 1.2 mm; wherein the length of the quartz crystal tuning fork base is within a range of 0.12 mm Lo 0.255 mm; wherein the width of the at least one groove formed in the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.015 mm and less than 0.052 mm; wherein the first vibrational portion of each of the first and second quartz crystal tuning fork tines has a first length and the second vibrational portion of each of the first and second quartz crystal tuning fork tines has a second length; wherein the first length of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than the second length of the second vibrational portion of the corresponding one of the first and second quartz crystal tuning fork tines; and wherein a length of the at least one groove formed in the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is within a range of 0.32 mm to 0.68 mm.
11. A quartz crystal unit according to claim 9; wherein the first vibrational portion of each of the first and second quartz crystal tuning fork tines has a first length and the second vibrational portion of each of the first and second quartz crystal tuning fork tines has a second length; wherein the second length of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is less than the first length of the first vibrational portion of the corresponding one of the first and second quartz crystal tuning fork tines; wherein each of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines has a central linear portion; wherein the at least one groove comprises a groove formed in the central linear portion of each of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines so that a width W.sub.2 of the groove formed in the central linear portion of each of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is less than 0.07 mm, a first distance in the width direction of the groove measured from a first outer edge of the groove to a first outer edge of the corresponding one of the first and second quartz crystal tuning fork tines being defined by W.sub.1 and a second distance in the width direction of the groove measured from a second outer edge opposite the first outer edge of the groove to a second outer edge opposite the first outer edge of the corresponding one of the first and second quartz crystal tuning fork tines being defined by W.sub.3, and so that each of the first distance W.sub.1 and the second distance W.sub.3 is less than 0.015 mm; wherein the quartz crystal tuning fork base has a first base portion including a first length and a first width, a second base portion including a second length less than the first length and a second width equal to the first width, and a third base portion including a third length less than the first length and a third width less than each of the first and second widths, the third base portion being formed between the first and second base portions, the second base portion being connected to the first base portion through the third base portion, each of the first and second quartz crystal tuning fork tines being connected to the first base portion of the quartz crystal tuning fork base, the third width of the third base portion of the quartz crystal tuning fork base being within a range of 0.04 mm to 0.125 mm; wherein a first frame portion is connected to the second base portion of the quartz crystal tuning fork base through a first connecting portion and a second frame portion is connected to the second base portion of the quartz crystal tuning fork base through a second connecting portion so that the second base portion of the quartz crystal tuning fork base and the first and second connecting portions have a concave shape or a U-shape with the first and second frame portions, each of the first and second frame portions having a width and a length within a range of 0.25 mm to 0.85 mm, and each of the first and second connecting portions having a width within a range of 0.021 mm to 0.125 mm; wherein the width of each of the first and second connecting portions is greater than or equal to the width of each of the first and second frame portions; wherein the case has first and second mounting portions; wherein the first frame portion is mounted on the first mounting portion of the case and the second frame portion is mounted on the second mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
12. A quartz crystal unit according to claim 11; wherein the width W.sub.2 of the groove formed in the central linear portion of each of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.015 mm and less than 0.052 mm; wherein each of the first distance W.sub.1 and the second distance W.sub.3 is greater than 0.004 mm and less than 0.015 mm; wherein when a ratio of the second width of the second vibrational portion of each of the first and second quartz crystal tuning fork tines and the width of each of the first and second frame portions is defined by a first ratio, the first ratio is within a range of 2.3 to 5.5; and wherein when a ratio of the second width of the second vibrational portion of each of the first and second quartz crystal tuning fork tines and the third width of the third base portion of the quartz crystal tuning fork base is defined by a second ratio, the second ratio is within a range of 1.2 to 2.8.
13. A quartz crystal unit according to claim 9; wherein the second vibrational portion of each of the first and second quartz crystal tuning fork tines comprises a plurality of portions having a first portion including a third width and a third length, and a second portion including a fourth width greater than the third width and a fourth length greater than the third length; wherein the first portion of the second vibrational portion of the first quartz crystal tuning fork tine is formed between the second portion of the second vibrational portion of the first quartz crystal tuning fork tine and the first vibrational portion of the first quartz crystal tuning fork tine; wherein the first portion of the second vibrational portion of the second quartz crystal tuning fork tine is formed between the second portion of the second vibrational portion of the second quartz crystal tuning fork tine and the first vibrational portion of the second quartz crystal tuning fork tine; wherein the third width of the first portion of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.04 mm and less than 0.15 mm and the fourth width of the second portion of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.15 mm and less than 0.23 mm; wherein the third length of the first portion of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.03 mm and less than 0.15 mm and the fourth length of the second portion of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.16 mm and less than 0.49 mm; wherein the first vibrational portion of each of the first and second quartz crystal tuning fork tines has a first length and the second vibrational portion of each of the first and second quartz crystal tuning fork tines has a second length; wherein the first length of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than the second length of the second vibrational portion of the corresponding one of the first and second quartz crystal tuning fork tines; wherein the quartz crystal tuning fork base has a first base portion, a second base portion and two cut portions formed between the first and second base portions, the first vibrational portion of each of the first and second quartz crystal tuning fork tines being connected to the first base portion of the quartz crystal tuning fork base; and wherein two frame portions are connected to the second base portion of the quartz crystal tuning fork base so that the two frame portions extend in a common direction with the first and second quartz crystal tuning fork tines outside the first and second quartz crystal tuning fork tines.
14. A quartz crystal unit according to claim 9; wherein the first vibrational portion of each of the first and second quartz crystal tuning fork tines has a first length and the second vibrational portion of each of the first and second quartz crystal tuning fork tines has a second length greater than 0.2 mm and less than 0.7 mm; wherein the second length of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is less than the first length of the first vibrational portion of the corresponding one of the first and second quartz crystal tuning fork tines; wherein the at least one groove comprises a groove formed in each of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines so that a width of the groove formed in each of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.015 mm and less than 0.04 mm, and greater than each of a first distance in the width direction of the groove measured from a first outer edge of the groove to a first outer edge of the corresponding one of the first and second quartz crystal tuning fork tines and a second distance in the width direction of the groove measured from a second outer edge opposite the first outer edge of the groove to a second outer edge opposite the first outer edge of the corresponding one of the first and second quartz crystal tuning fork tines, each of the first and second distances being greater than 0.001 mm and less than 0.0035 mm, and so that a length of the groove formed in each of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is within a range of 0.28 mm to 0.52 mm; wherein the overall length of the quartz crystal tuning fork resonator is within a range of 0.8 mm to 1.2 mm; wherein the quartz crystal tuning fork base has a first base portion including a first width and a second base portion including a second width greater than the first width; wherein the case has a mounting portion; wherein the second base portion of the quartz crystal tuning fork base is mounted on the mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
15. A quartz crystal unit according to claim 9; wherein the first vibrational portion of each of the first and second quartz crystal tuning fork tines has a first length and the second vibrational portion of each of the first and second quartz crystal tuning fork tines has a second length greater than 0.2 mm and less than 0.7 mm; wherein the second length of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is less than the first length of the first vibrational portion of the corresponding one of the first and second quartz crystal tuning fork tines; wherein the at least one groove comprises a groove formed in each of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines so that a width of the groove formed in each of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than a distance in the width direction of the groove measured from an outer edge of the groove to an outer edge of the corresponding one of the first and second quartz crystal tuning fork tines; wherein the quartz crystal tuning fork base has a side surface; wherein each of the first and second quartz crystal tuning fork tines has an end portion including an outer edge; wherein the end portion of each of the first and second quartz crystal tuning fork tines is connected to the side surface of the quartz crystal tuning fork base; wherein a distance in the length direction of the groove measured from an outer edge of the groove to the outer edge of the end portion of the first quartz crystal tuning fork tine is defined by a first distance; wherein a distance in the length direction of the groove measured from an outer edge of the groove to the outer edge of the end portion of the second quartz crystal tuning fork tine is defined by a second distance; wherein each of the first and second distances is within a range of 0.01 mm to 0.065 mm; and wherein the overall length of the quartz crystal tuning fork resonator is within a range of 0.8 mm to 1.2 mm.
16. A quartz crystal unit according to claim 9; wherein the first vibrational portion of each of the first and second quartz crystal tuning fork tines has a first length and the second vibrational portion of each of the first and second quartz crystal tuning fork tines has a second length greater than 0.2 mm and less than 0.7 mm; wherein the first length of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than the second length of the second vibrational portion of the corresponding one of the first and second quartz crystal tuning fork tines; wherein each of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines has a central linear portion; wherein the at least one groove comprises a groove formed in the central linear portion of each of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines so that a width W.sub.2 of the groove formed in the central linear portion of each of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is less than 0.07 mm and greater than each of a first distance in the width direction of the groove measured from a first outer edge of the groove to a first outer edge of the corresponding one of the first and second quartz crystal tuning fork tines and a second distance in the width direction of the groove measured from a second outer edge opposite the first outer edge of the groove to a second outer edge opposite the first outer edge of the corresponding one of the first and second quartz crystal tuning fork tines, each of the first and second distances being less than 0.015 mm; wherein the second vibrational portion of each of the first and second quartz crystal tuning fork tines comprises a plurality of portions having a first portion including a third width and a third length, and a second portion including a fourth width greater than the third width and a fourth length greater than the third length; wherein the first portion of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is formed between the second portion of the second vibrational portion of the corresponding one of the first and second quartz crystal tuning fork tines and the first vibrational portion of the corresponding one of the first and second quartz crystal tuning fork tines; wherein the quartz crystal tuning fork base has a first base portion including a first length and a first width, a second base portion including a second length less than the first length and a second width equal to the first width, and a third base portion including a third length and a third width less than each of the first and second widths, the third base portion being formed between the first and second base portions, the second base portion being connected to the first base portion through the third base portion, the first vibrational portion of each of the first and second quartz crystal tuning fork tines being connected to the first base portion of the quartz crystal tuning fork base; wherein a first frame portion is connected to the second base portion of the quartz crystal tuning fork base through a first connecting portion and a second frame portion is connected to the second base portion of the quartz crystal tuning fork base through a second connecting portion so that the second base portion of the quartz crystal tuning fork base and the first and second connecting portions have a concave shape or a U-shape with the first and second frame portions, each of the first and second frame portions having a mounting portion including a width, and each of the first and second connecting portions having a width; wherein the width of each of the first and second connecting portions is greater than or equal to the width of the mounting portion of each of the first and second frame portions; wherein the case has first and second mounting portions; wherein the mounting portion of the first frame portion is mounted on the first mounting portion of the case and the mounting portion of the second frame portion is mounted on the second mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
17. A quartz crystal unit according to claim 16; wherein the first distance is defined by W.sub.1 and the second distance is defined by W.sub.3; wherein each of the first distance W.sub.1 and the second distance W.sub.3 is greater than 0.004 mm and less than 0.015 mm; wherein the third width of the third base portion of the quartz crystal tuning fork base is within a range of 0.04 mm to 0.125 mm; wherein a length of each of the first and second frame portions is within a range of 0.25 mm to 0.85 mm and a width of each of the first and second frame portions is within a range of 0.02 mm to 0.055 mm; and wherein a width of each of the first and second connecting portions is within a range of 0.021 mm to 0.125 mm.
18. A quartz crystal unit according to claim 9; wherein the first vibrational portion of each of the first and second quartz crystal tuning fork tines has a first length; wherein the second vibrational portion of each of the first and second quartz crystal tuning fork tines has a second length greater than 0.2 mm and less than 0.7 mm; wherein the first length of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than the second length of the second vibrational portion of the corresponding one of the first and second quartz crystal tuning fork tines; wherein the quartz crystal tuning fork base has a first base portion, a second base portion including a first portion and a second portion and a cut portion formed between the first base portion and the first portion of the second base portion, each of the first and second quartz crystal tuning fork tines being connected to the first base portion of the quartz crystal tuning fork base; wherein a width of the first base portion of the quartz crystal tuning fork base is within a range of 0.25 mm to 0.43 mm and a length of the first base portion of the quartz crystal tuning fork base is within a range of 0.025 mm to 0.15 mm; wherein each of the first and second portions of the second base portion of the quartz crystal tuning fork base has a width and a side surface, the side surface of the first portion of the second base portion being connected to the side surface of the second portion of the second base portion; wherein the width of the first portion of the second base portion of the quartz crystal tuning fork base is less than the width of the first base portion of the quartz crystal tuning fork base and is within a range of 0.18 mm to 0.285 mm, and the width of the second portion of the second base portion of the quartz crystal tuning fork base is within a range of 0.035 mm to 0.125 mm; wherein the case has first and second mounting portions; wherein the first portion of the second base portion of the quartz crystal tuning fork base is mounted on the first mounting portion of the case and the second portion of the second base portion of the quartz crystal tuning fork base is mounted on the second mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
19. A quartz crystal unit according to claim 9; wherein the first vibrational portion of each of the first and second quartz crystal tuning fork tines has a first length; wherein the second vibrational portion of each of the first and second quartz crystal tuning fork tines has a second length greater than 0.2 mm and less than 0.7 mm; wherein the first length of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than the second length of the second vibrational portion of the corresponding one of the first and second quartz crystal tuning fork tines; wherein the at least one groove comprises a groove formed in at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines so that a width of the groove formed in the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is less than 0.07 mm, a first distance in the width direction of the groove measured from a first outer edge of the groove to a first outer edge of the corresponding one of the first and second quartz crystal tuning fork tines being defined by W.sub.1 and a second distance in the width direction of the groove measured from a second outer edge opposite the first outer edge of the groove to a second outer edge opposite the first outer edge of the corresponding one of the first and second quartz crystal tuning fork tines being defined by W.sub.3, and so that the first distance W.sub.1 is less than 0.015 mm and the second distance W.sub.3 is greater than the first distance W.sub.1; wherein the quartz crystal tuning fork base has a first base portion including a first width, and a second base portion including a second width greater than the first width and a second length; wherein the second width of the second base portion of the quartz crystal tuning fork base is within a range of 0.32 mm to 0.5 mm and the second length of the second base portion of the quartz crystal tuning fork base is within a range of 0.12 mm to 0.25 mm; wherein the case has a mounting portion; wherein the second base portion of the quartz crystal tuning fork base is mounted on the mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
20. A quartz crystal unit according to claim 9; wherein the first vibrational portion of each of the first and second quartz crystal tuning fork tines has a first length; wherein the second vibrational portion of each of the first and second quartz crystal tuning fork tines has a second length greater than 0.2 mm and less than 0.7 mm; wherein the first length of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than the second length of the second vibrational portion of the corresponding one of the first and second quartz crystal tuning fork tines; wherein the at least one groove comprises a groove formed in at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines so that a distance in the width direction of the groove measured from an outer edge of the groove to an outer edge of the corresponding one of the first and second quartz crystal tuning fork tines is less than 0.015 mm; wherein an area S of the groove formed in the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is defined by S=W.sub.2l.sub.1, where W.sub.2 and l.sub.1 represent a width and a length, respectively, of the groove formed in the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines; and wherein the area S of the groove is greater than 0.01 mm.sup.2 and less than 0.043 mm.sup.2.
21. A quartz crystal unit according to claim 9; wherein the overall length of the quartz crystal tuning fork resonator is within a range of 1.2 mm to 2 mm; wherein each of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines has a central linear portion; wherein the at least one groove comprises a groove formed in the central linear portion of at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines so that a width of the groove formed in the central linear portion of the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is less than 0.07 mm, a first distance in the width direction of the groove measured from a first outer edge of the groove to a first outer edge of the corresponding one of the first and second quartz crystal tuning fork tines being defined by W.sub.1 and a second distance in the width direction of the groove measured from a second outer edge opposite the first outer edge of the groove to a second outer edge opposite the first outer edge of the corresponding one of the first and second quartz crystal tuning fork tines being defined by W.sub.3, and so that each of the first distance W.sub.1 and the second distance W.sub.3 is less than 0.015 mm; wherein the quartz crystal tuning fork base has a first base portion including a first length and a first width W.sub.5, a second base portion including a second length and a second width W.sub.6 equal to the first width W.sub.5, and a third base portion including a third length and a third width less than each of the first width W.sub.5 and the second width W.sub.6 so that the third base portion is formed between the first and second base portions, each of the first and second quartz crystal tuning fork tines being connected to the first base portion of the quartz crystal tuning fork base, the first width W.sub.5 of the first base portion being within a range of 0.25 mm to 0.38 mm, and the third width of the third base portion being within a range of 0.1 mm to 0.2 mm; wherein the first length of the first base portion is defined by l.sub.6 and the third length of the third base portion is defined by l.sub.7; wherein a ratio l.sub.6/l.sub.7 of the first length l.sub.6 of the first base portion and the third length l.sub.7 of the third base portion is defined by l.sub.67=l.sub.6/l.sub.7; wherein the ratio l.sub.67 is within a range of 0.8 to 1.05; wherein the length of the quartz crystal tuning fork base is defined by l.sub.2 and the second length of the second base portion of the quartz crystal tuning fork base is defined by l.sub.4; wherein when a length l.sub.5 is defined by l.sub.5=l.sub.2l.sub.4, the second length l.sub.4 is less than or equal to the length l.sub.5 and is within a range of 0.05 mm to 0.3 mm; wherein a first frame portion is connected to the second base portion of the quartz crystal tuning fork base through a first connecting portion and a second frame portion is connected to the second base portion of the quartz crystal tuning fork base through a second connecting portion so that the second base portion of the quartz crystal tuning fork base and the first and second connecting portions have a concave shape or a U-shape with the first and second frame portions, each of the first and second connecting portions having a width within a range of 0.021 mm to 0.125 mm; wherein the case has first and second mounting portions; wherein the first frame portion is mounted on the first mounting portion of the case and the second frame portion is mounted on the second mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
22. A quartz crystal unit comprising: a case; a quartz crystal tuning fork resonator; and a lid; wherein the quartz crystal tuning fork resonator has a quartz crystal tuning fork base, and first and second quartz crystal tuning fork tines connected to the quartz crystal tuning fork base, each of the first and second quartz crystal tuning fork tines comprising a plurality of different widths having a first width and a second width greater than the first width, each of the first and second quartz crystal tuning fork tines having a first main surface and a second main surface opposite the first main surface; wherein at least one groove is formed in at least one of the first and second main surfaces of each of the first and second quartz crystal tuning fork tines so that a distance in the width direction of the at least one groove measured from an outer edge of the at least one groove to an outer edge of the corresponding one of the first and second quartz crystal tuning fork tines is less than 0.021 mm; and wherein the first width of each of the first and second quartz crystal tuning fork tines is greater than 0.03 mm and less than 0.075 mm and the second width of each of the first and second quartz crystal tuning fork tines is greater than 0.04 mm and less than 0.23 mm.
23. A quartz crystal unit according to claim 22; wherein each of the first and second main surfaces of each of the first and second quartz crystal tuning fork tines has a central linear portion; wherein the at least one groove comprises a groove formed in the central linear portion of at least one of the first and second main surfaces of each of the first and second quartz crystal tuning fork tines so that a width W.sub.2 of the groove formed in the central linear portion of the at least one of the first and second main surfaces of each of the first and second quartz crystal tuning fork tines is less than 0.07 mm, a first distance in the width direction of the groove measured from a first outer edge of the groove to a first outer edge of the corresponding one of the first and second quartz crystal tuning fork tines being defined by W.sub.1 and a second distance in the width direction of the groove measured from a second outer edge opposite the first outer edge of the groove to a second outer edge opposite the first outer edge of the corresponding one of the first and second quartz crystal tuning fork tines being defined by W.sub.3, and so that each of the first distance W.sub.1 and the second distance W.sub.3 is less than 0.015 mm; wherein an overall length of the quartz crystal tuning fork resonator is less than 2.18 mm; and wherein a length of the quartz crystal tuning fork base is less than 0.5 mm.
24. A quartz crystal unit according to claim 23; wherein the overall length of the quartz crystal tuning fork resonator is within a range of 0.8 mm to 1.2 mm; wherein the width W2 of the groove formed in the central linear portion of the at least one of the first and second main surfaces of each of the first and second quartz crystal tuning fork tines is greater than 0.015 mm and less than 0.04 mm; wherein a length of the groove formed in the central linear portion of the at least one of the first and second main surfaces of each of the first and second quartz crystal tuning fork tines is within a range of 0.28 mm to 0.52 mm; wherein the quartz crystal tuning fork base has a first base portion including a first width and a second base portion including a second width greater than the first width; wherein the case has a mounting portion; wherein the second base portion of the quartz crystal tuning fork base is mounted on the mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
25. A quartz crystal unit according to claim 23; wherein each of the first distance W.sub.1 and the second distance W.sub.3 is greater than 0.001 mm and less than 0.0035 mm; wherein a length of the groove formed in the central linear portion of the at least one of the first and second main surfaces of each of the first and second quartz crystal tuning fork tines is within a range of 0.28 mm to 0.52 mm; wherein the quartz crystal tuning fork base has a first base portion including a first width and a second base portion including a second width greater than the first width, the second width of the second base portion of the quartz crystal tuning fork base being within a range of 0.32 mm to 0.5 mm; wherein the case has a mounting portion; wherein the second base portion of the quartz crystal tuning fork base is mounted on the mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
26. A quartz crystal unit according to claim 23; wherein the overall length of the quartz crystal tuning fork resonator is within a range of 1.2 mm to 2 mm; wherein the quartz crystal tuning fork base has a first base portion including a first width W.sub.5, a second base portion including a second length and a second width W.sub.6 equal to the first width W.sub.5, and two cut portions formed between the first and second base portions, each of the first and second quartz crystal tuning fork tines being connected to the first base portion of the quartz crystal tuning fork base; wherein the length of the quartz crystal tuning fork base is defined by l.sub.2 and the second length of the second base portion of the quartz crystal tuning fork base is defined by l.sub.4; wherein when a length l.sub.5 is defined by l.sub.5=l.sub.2l.sub.4, the second length l.sub.4 is less than or equal to the length l.sub.5 and is within a range of 0.05 mm to 0.3 mm; wherein a first frame portion is connected to the second base portion of the quartz crystal tuning fork base through a first connecting portion and a second frame portion is connected to the second base portion of the quartz crystal tuning fork base through a second connecting portion so that the second base portion of the quartz crystal tuning fork base and the first and second connecting portions have a concave shape or a U-shape with the first and second frame portions, each of the first and second connecting portions having a width within a range of 0.021 mm to 0.125 mm; wherein the case has first and second mounting portions; wherein the first frame portion is mounted on the first mounting portion of the case and the second frame portion is mounted on the second mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
27. A quartz crystal unit according to claim 26; wherein the length l.sub.2 of the quartz crystal tuning fork base is within a range of 0.12 mm to 0.255 mm; wherein each of the first distance W.sub.1 and the second distance W.sub.3 is greater than 0.004 mm and less than 0.015 mm; wherein the width W.sub.2 of the groove formed in the central linear portion of the at least one of the first and second main surfaces of each of the first and second quartz crystal tuning fork tines is greater than 0.015 mm and less than 0.052 mm, a length of the groove formed in the central linear portion of the at least one of the first and second main surfaces of each of the first and second quartz crystal tuning fork tines being defined by l.sub.1; wherein an area S of the groove formed in the central linear portion of the at least one of the first and second main surfaces of each of the first and second quartz crystal tuning fork tines is defined by S=W.sub.2l.sub.1; and wherein the area S of the groove formed in the central linear portion of the at least one of the first and second main surfaces of each of the first and second quartz crystal tuning fork tines is greater than 0.01 mm.sup.2 and less than 0.043 mm.sup.2.
28. A quartz crystal unit according to claim 23; wherein the overall length of the quartz crystal tuning fork resonator is within a range of 1.2 mm to 2 mm; wherein the quartz crystal tuning fork base has a first base portion including a first width, a second base portion including a second length and a second width substantially equal to the first width, and at least one cut portion formed between the first and second base portions so that a third base portion having a third length and a third width is formed between the first and second base portions, the first base portion being connected to the second base portion through the third base portion, and so that the third width of the third base portion is less than the first width of the first base portion and is within a range of 0.1 mm to 0.2 mm, and the third length of the third base portion is less than the second length of the second base portion, the second width of the second base portion being within a range of 0.215 mm to 0.41 mm; wherein the length of the quartz crystal tuning fork base is defined by l.sub.2 and the second length of the second base portion of the quartz crystal tuning fork base is defined by l.sub.4; and wherein when a length l.sub.5 is defined by l.sub.5=l.sub.2l.sub.4, the second length l.sub.4 is less than or equal to the length is and is within a range of 0.05 mm to 0.3 mm.
29. A quartz crystal unit according to claim 28; wherein the at least one cut portion has two cut portions formed between the first and second base portions of the quartz crystal tuning fork base; wherein a first frame portion is connected to the second base portion of the quartz crystal tuning fork base through a first connecting portion and a second frame portion is connected to the second base portion of the quartz crystal tuning fork base through a second connecting portion so that the second base portion of the quartz crystal tuning fork base and the first and second connecting portions have a concave shape or a U-shape with the first and second frame portions, each of the first and second connecting portions having a width within a range of 0.021 mm to 0.125 mm; wherein the first base portion of the quartz crystal tuning fork base has a first length; wherein when a ratio of the first length of the first base portion of the quartz crystal tuning fork base and the width of each of the first and second connecting portions is defined by a length-width ratio, the length-width ratio is within a range of 0.35 to 1.07; wherein the case has first and second mounting portions; wherein the first frame portion is mounted on the first mounting portion of the case and the second frame portion is mounted on the second mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
30. A quartz crystal unit according to claim 28; wherein the at least one cut portion has two cut portions formed between the first and second base portions of the quartz crystal tuning fork base; wherein a first frame portion is connected to the second base portion of the quartz crystal tuning fork base through a first connecting portion and a second frame portion is connected to the second base portion of the quartz crystal tuning fork base through a second connecting portion so that the second base portion of the quartz crystal tuning fork base and the first and second connecting portions have a concave shape or a U-shape with the first and second frame portions, each of the first and second connecting portions having a width within a range of 0.021 mm to 0.125 mm; wherein the first base portion of the quartz crystal tuning fork base has a first length; wherein when a ratio of the first length of the first base portion of the quartz crystal tuning fork base and the third length of the third base portion of the quartz crystal tuning fork base is defined by a length-length ratio, the length-length ratio is within a range of 0.8 to 1.05; wherein the case has first and second mounting portions; wherein the first frame portion is mounted on the first mounting portion of the case and the second frame portion is mounted on the second mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
31. A quartz crystal unit according to claim 22; wherein each of the first and second quartz crystal tuning fork tines comprises a plurality of vibrational portions having a first vibrational portion including the first width and a first length, and a second vibrational portion including the second width greater than the first width and a second length less than the first length, the first vibrational portion of each of the first and second quartz crystal tuning fork tines having a first main surface and a second main surface opposite the first main surface; wherein each of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines has a central linear portion; and wherein the at least one groove comprises a groove formed in the central linear portion of at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines so that a width W.sub.2 of the groove formed in the central linear portion of the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is less than 0.07 mm, a first distance in the width direction of the groove measured from a first outer edge of the groove to a first outer edge of the corresponding one of the first and second quartz crystal tuning fork tines being defined by W.sub.1 and a second distance in the width direction of the groove measured from a second outer edge opposite the first outer edge of the groove to a second outer edge opposite the first outer edge of the corresponding one of the first and second quartz crystal tuning fork tines being defined by W.sub.3, and so that each of the first distance W.sub.1 and the second distance W.sub.3 less than 0.015 mm; wherein an overall length of the quartz crystal tuning fork resonator is less than 2.18 mm; and wherein a length of the quartz crystal tuning fork base is less than 0.5 mm.
32. A quartz crystal unit according to claim 31; wherein the overall length of the quartz crystal tuning fork resonator is within a range of 0.8 mm to 1.2 mm; wherein the width W.sub.2 of the groove formed in the central linear portion of the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.015 mm and less than 0.04 mm; wherein a length of the groove formed in the central linear portion of the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is within a range of 0.28 mm to 0.52 mm; wherein the quartz crystal tuning fork base has a first base portion including a first width and a second base portion including a second width greater than the first width, the second width of the second base portion of the quartz crystal tuning fork base being within a range of 0.32 mm to 0.5 mm; wherein the case has a mounting portion; wherein the second base portion of the quartz crystal tuning fork base is mounted on the mounting portion of the case; and wherein the lid is connected to the case.
33. A quartz crystal unit according to claim 31; wherein the first width of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is defined by W; wherein the second width of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is defined by Wg; wherein the second width Wg of the second vibrational portion is less than three times of the first width W of the first vibrational portion; wherein a difference of the second width Wg and the first width W is defined by WgW; and wherein the difference WgW is within a range of 0.008 mm to 0.1 mm.
34. A quartz crystal unit according to claim 31; wherein the second length of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.2 mm and less than 0.7 mm; wherein each of the first distance W.sub.1 and the second distance W.sub.3 is greater than 0.001 mm and less than 0.0035 mm; wherein a length of the groove formed in the central linear portion of the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is within a range of 0.28 mm to 0.52 mm; wherein the quartz crystal tuning fork base has a first base portion including a first width and a second base portion including a second width greater than the first width; wherein the case has a mounting portion; wherein the second base portion of the quartz crystal tuning fork base is mounted on the mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
35. A quartz crystal unit according to claim 31; wherein the overall length of the quartz crystal tuning fork resonator is within a range of 0.8 mm to 1.2 mm; wherein a length of the groove formed in the central linear portion of the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is defined by l.sub.1 and is within a range of 0.28 mm to 0.52 mm; wherein an area S of the groove formed in the central linear portion of the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is defined by S=W.sub.2l.sub.1, where W.sub.2 represents the width of the groove formed in the central linear portion of the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines; wherein the area S of the groove formed in the central linear portion of the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.01 mm.sup.2 and less than 0.043 mm.sup.2; wherein the quartz crystal tuning fork base has a first base portion including a first width, and a second base portion including a second length and a second width greater than the first width, the second length of the second base portion being within a range of 0.05 mm to 0.3 mm; wherein the case has a mounting portion; wherein the second base portion of the quartz crystal tuning fork base is mounted on the mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
36. A quartz crystal unit according to claim 31; wherein a spaced-apart distance between the first vibrational portion of the first quartz crystal tuning fork tine and the first vibrational portion of the second quartz crystal tuning fork tine is defined by W.sub.4; wherein the width W.sub.2 of the groove formed in the central linear portion of the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is less than the spaced-apart distance W.sub.4 between the first vibrational portion of the first quartz crystal tuning fork tine and the first vibrational portion of the second quartz crystal tuning fork tine; wherein a length of the groove formed in the central linear portion of the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is within a range of 0.28 mm to 0.52 mm; wherein the second length of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.2 mm and less than 0.7 mm; wherein the quartz crystal tuning fork base has a first base portion including a first width, and a second base portion including a second length and a second width greater than the first width, the second length of the second base portion of the quartz crystal tuning fork base being within a range of 0.05 mm to 0.3 mm; wherein the case has a mounting portion; wherein the second base portion of the quartz crystal tuning fork base is mounted on the mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
37. A quartz crystal unit according to claim 31; wherein the overall length of the quartz crystal tuning fork resonator is within a range of 0.8 mm to 1.2 mm; wherein the width W.sub.2 of the groove formed in the central linear portion of the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.015 mm and less than 0.052 mm; wherein the quartz crystal tuning fork base has a first base portion including a first width W.sub.5 and a first length, a second base portion including a second width W.sub.6 greater than or equal to the first width W.sub.5 and a second length less than the first length, and two cut portions formed between the first and second base portions, each of the first and second quartz crystal tuning fork tines being connected to the first base portion of the quartz crystal tuning fork base; wherein a first frame portion is connected to the second base portion of the quartz crystal tuning fork base through a first connecting portion and a second frame portion is connected to the second base portion of the quartz crystal tuning fork base through a second connecting portion so that the second base portion of the quartz crystal tuning fork base and the first and second connecting portions have a concave shape or a U-shape with the first and second frame portions, each of the first and second frame portions having a width and a length, and each of the first and second connecting portions having a width; wherein the length of each of the first and second frame portions is within a range of 0.25 mm to 0.65 mm and the width of each of the first and second connecting portions is within a range of 0.021 mm to 0.125 mm; and wherein the width of each of the first and second frame portions is less than or equal to the first width of the first vibrational portion of each of the first and second quartz crystal tuning fork tines.
38. A quartz crystal unit according to claim 31; wherein the second width of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is defined by W.sub.g; wherein the first width of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is defined by W; wherein a ratio of the second width W.sub.g of the second vibrational portion of each of the first and second quartz crystal tuning fork tines and the first width W of the first vibrational portion of the corresponding one of the first and second quartz crystal tuning fork tines is defined by W.sub.9/W; wherein the ratio W.sub.9/W is greater than or substantially equal to 3.0 and less than 6.5; wherein the second length of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.2 mm and less than 0.7 mm; wherein the quartz crystal tuning fork base has a first base portion including a first width, a second base portion including a second width greater than or equal to the first width, and a third base portion formed between the first and second base portions so that a width of the third base portion is less than each of the first width of the first base portion and the second width of the second base portion; wherein at least one frame portion having a width is connected to the second base portion of the quartz crystal tuning fork base through a connection portion so that the at least one frame portion extends in a common direction with the first and second quartz crystal tuning fork tines outside the first and second quartz crystal tuning fork tines, a width of the connecting portion being within a range of 0.021 mm to 0.125 mm; and wherein the width of the at least one frame portion is less than or equal to the first width of the first vibrational portion of each of the first and second quartz crystal tuning fork tines.
39. A quartz crystal unit according to claim 31; wherein the second length of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.2 mm and less than 0.7 mm; wherein the second vibrational portion of each of the first and second quartz crystal tuning fork tines comprises a plurality of portions having a first portion including a third width and a third length, and a second portion including a fourth width greater than the third width and a fourth length greater than the third length; wherein the first portion of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is formed between the second portion of the second vibrational portion of the corresponding one of the first and second quartz crystal tuning fork tines and the first vibrational portion of the corresponding one of the first and second quartz crystal tuning fork tines; wherein the quartz crystal tuning fork base has a first base portion including a first length and a first width W.sub.5, a second base portion including a second length less than the first length and a second width W.sub.6 greater than or equal to the first width W.sub.5, and a third base portion including a third length less than the first length and a third width less than each of the first width W.sub.5 and the second width W.sub.6, the third base portion being formed between the first and second base portions, the second base portion being connected to the first base portion through the third base portion, the third length of the third base portion being within a range of 0.012 mm to 0.055 mm, and the third width of the third base portion being within a range of 0.04 mm to 0.125 mm, each of the first and second quartz crystal tuning fork tines being connected to the first base portion of the quartz crystal tuning fork base; wherein a first frame portion is connected to the second base portion of the quartz crystal tuning fork base through a first connecting portion and a second frame portion is connected to the second base portion of the quartz crystal tuning fork base through a second connecting portion so that the second base portion of the quartz crystal tuning fork base and the first and second connecting portions have a concave shape or a U-shape with the first and second frame portions; wherein the case has first and second mounting portions; wherein the first frame portion is mounted on the first mounting portion of the case and the second frame portion is mounted on the second mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
40. A quartz crystal unit according to claim 39; wherein the third width of the first portion of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.04 mm and less than 0.15 mm and the fourth width of the second portion of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.15 mm and less than 0.23 mm; wherein the third length of the first portion of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.03 mm and less than 0.15 mm and the fourth length of the second portion of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.18 mm and less than 0.45 mm; wherein the first width W.sub.5 of the first base portion of the quartz crystal tuning fork base is within a range of 0.25 mm to 0.38 mm and the first length of the first base portion of the quartz crystal tuning fork base is within a range of 0.025 mm to 0.13 mm; wherein the second width W.sub.6 of the second base portion of the quartz crystal tuning fork base is within a range of 0.25 mm to 0.52 mm and the second length of the second base portion of the quartz crystal tuning fork base is within a range of 0.02 mm to 0.072 mm; wherein each of the first and second frame portions has a width and a length within a range of 0.25 mm to 0.85 mm; wherein each of the first and second connecting portions has a width; and wherein the width of each of the first and second connecting portions is greater than or equal to the width of each of the first and second frame portions.
41. A quartz crystal unit according to claim 22; wherein an overall length of the quartz crystal tuning fork resonator is less than 2.18 mm; wherein a length of the quartz crystal tuning fork base is less than 0.5 mm; wherein each of the first and second quartz crystal tuning fork tines comprises a plurality of vibrational portions having a first vibrational portion including the first width and a first length, and a second vibrational portion including the second width greater than Lite first width and a second length less than the first length, the first vibrational portion of each of the first and second quartz crystal tuning fork tines having a first main surface and a second main surface opposite the first main surface; wherein the at least one groove comprises a groove formed in at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines so that a width of the groove formed in the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is less than 0.07 mm and a distance in the width direction of the groove measured from an outer edge of the groove to an outer edge of the corresponding one of the first and second quartz crystal tuning fork tines is less than 0.015 mm; wherein the quartz crystal tuning fork base has a first base portion including a first width, and a second base portion including a second width greater than the first width and a second length; wherein the case has a mounting portion; wherein the second base portion of the quartz crystal tuning fork base is mounted on the mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
42. A quartz crystal unit according to claim 41; wherein the overall length of the quartz crystal tuning fork resonator is within a range of 1.2 mm to 2 mm; wherein the width of the groove formed in the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.015 mm and less than 0.04 mm and the distance in the width direction of the groove measured from the outer edge of the groove to the outer edge of the corresponding one of the first and second quartz crystal tuning fork tines is greater than 0.004 mm and less than 0.015 mm; wherein the second width of the second base portion of the quartz crystal tuning fork base is within a range of 0.32 mm to 0.5 mm and the second length of the second base portion of the quartz crystal tuning fork base is within a range of 0.05 mm to 0.3 mm; wherein the first width of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.03 mm and less than 0.075 mm and the second width of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.04 mm and less than 0.23 mm; and wherein the second length of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.2 mm and less than 0.7 mm.
43. A quartz crystal unit according to claim 42; wherein the overall length of the quartz crystal tuning fork resonator is within a range of 1.2 mm to 2 mm; wherein the second length of the second base portion of the quartz crystal tuning fork base is within a range of 0.05 mm to 0.3 mm; wherein a length of the groove formed in the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is within a range of 0.32 mm to 0.85 mm; wherein the second length of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.2 mm and less than 0.7 mm; wherein a spaced-apart distance between the first vibrational portion of the first quartz crystal tuning fork tine and the first vibrational portion of the second quartz crystal tuning fork tine is defined by W.sub.4; and wherein the width of the groove formed in the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is less than the spaced-apart distance W.sub.4 between the first vibrational portion of the first quartz crystal tuning fork tine and the first vibrational portion of the second quartz crystal tuning fork tine.
44. A quartz crystal unit according to claim 43; wherein an area S of the groove formed in the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is defined by S=W.sub.2l.sub.1, where W.sub.2 and .sub.1 represent the width and the length, respectively, of the groove formed in the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines; and wherein the area S of the groove formed in the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.01 mm.sup.2 and less than 0.043 mm.sup.2.
45. A quartz crystal unit according to claim 41; wherein the overall length of the quartz crystal tuning fork resonator is within a range of 1.2 mm to 2 mm; wherein the second vibrational portion of each of the first and second quartz crystal tuning fork tines has a second length greater than 0.2 mm and less than 0.7 mm; wherein the at least one groove comprises a groove formed in each of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines so that a width of the groove formed in each of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is less than 0.07 mm, a first distance in the width direction of the groove measured from a first outer edge of the groove to a first outer edge of the corresponding one of the first and second quartz crystal tuning fork tines being defined by W.sub.1 and a second distance in the width direction of the groove measured from a second outer edge opposite the first outer edge of the groove to a second outer edge opposite the first outer edge of the corresponding one of the first and second quartz crystal tuning fork tines being defined by W.sub.3, and so that the first distance W.sub.1 is less than 0.015 mm and the second distance W.sub.3 is greater than the first distance W.sub.1; wherein the quartz crystal tuning fork base has a first base portion including a first width, and a second base portion including a second width greater than the first width and a second length; wherein the second width of the second base portion of the quartz crystal tuning fork base is within a range of 0.32 mm to 0.5 mm and the second length of the second base portion of the quartz crystal tuning fork base is within a range of 0.12 mm to 0.25 mm; wherein the case has a mounting portion; wherein the second base portion of the quartz crystal tuning fork base is mounted on the mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
46. A quartz crystal oscillator comprising: a quartz crystal oscillating circuit comprised of a plurality of capacitors, a resistor and a quartz crystal unit having a case, a quartz crystal tuning fork resonator and a lid; wherein the quartz crystal tuning fork resonator has a quartz crystal tuning fork base, and first and second quartz crystal tuning fork tines connected to the quartz crystal tuning fork base, each of the first and second quartz crystal tuning fork tines comprising a plurality of different widths having a first width and a second width greater than the first width, each of the first and second quartz crystal tuning fork tines having a first main surface and a second main surface opposite the first main surface; wherein at least one groove is formed in at least one of the first and second main surfaces of each of the first and second quartz crystal tuning fork tines so that a distance in the width direction of the at least one groove measured from an outer edge of the at least one groove to an outer edge of the corresponding one of the first and second quartz crystal tuning fork tines is less than 0.021 mm; and wherein the first width of each of the first and second quartz crystal tuning fork tines is greater than 0.03 mm and less than 0.075 mm and the second width of each of the first and second quartz crystal tuning fork tines is greater than 0.04 mm and less than 0.23 mm.
47. A quartz crystal oscillator according to claim 46; wherein an overall length of the quartz crystal tuning fork resonator is within a range of 1.2 mm to 2 mm; wherein each of the first and second main surfaces of each of the first and second quartz crystal tuning fork tines has a central linear portion; and wherein the at least one groove comprises a groove formed in the central linear portion of at least one of the first and second main surfaces of each of the first and second quartz crystal tuning fork tines so that a width W.sub.2 of the groove formed in the central linear portion of the at least one of the first and second main surfaces of each of the first and second quartz crystal tuning fork tines is less than 0.07 mm, a first distance in the width direction of the groove measured from a first outer edge of the groove to a first outer edge of the corresponding one of the first and second quartz crystal tuning fork tines being defined by W.sub.1 and a second distance in the width direction of the groove measured from a second outer edge opposite the first outer edge of the groove to a second outer edge opposite the first outer edge of the corresponding one of the first and second quartz crystal tuning fork tines being defined by W.sub.3, and so that each of the first distance W.sub.1 and the second distance W.sub.3 is less than 0.015 mm; and wherein a length of the quartz crystal tuning fork base is less than 0.5 mm.
48. A quartz crystal oscillator according to claim 47; wherein the quartz crystal tuning fork base has a first base portion including a first width W.sub.5, a second base portion including a second length and a second width W.sub.6 greater than the first width W.sub.5, and a third base portion including a third width less than each of the first width W.sub.5 and the second width W.sub.6 so that third base portion is formed between the first and second base portions, each of the first and second quartz crystal tuning fork tines being connected to the first base portion of the quartz crystal tuning fork base, the second width W.sub.6 of the second base portion being within a range of 0.25 mm to 0.52 mm, and the third width of the third base portion being within a range of 0.1 mm to 0.2 mm; wherein the length of the quartz crystal tuning fork base is defined by l.sub.2 and the second length of the second base portion of the quartz crystal tuning fork base is defined by l.sub.4; wherein when a length l.sub.5 is defined by l.sub.5=l.sub.2l.sub.4, the second length l.sub.4 is less than or equal to the length l.sub.5 and is within a range of 0.05 mm to 0.3 mm; wherein two frame portions having first and second frame portions are connected to the second base portion of the quartz crystal tuning fork base; wherein the first frame portion is connected to the second base portion of the quartz crystal tuning fork base and the second frame portion is connected to the second base portion of the quartz crystal tuning fork base so that the second base portion of the quartz crystal tuning fork base has a concave shape or a U-shape with the first and second frame portions, wherein the case has first and second mounting portions; wherein the first frame portion is mounted on the first mounting portion of the case and the second frame portion is mounted on the second mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
49. A quartz crystal oscillator according to claim 48; wherein the length l.sub.2 of the quartz. crystal tuning fork base is within a range of 0.12 mm to 0.255 mm; wherein each of the first distance W.sub.1 and the second distance W.sub.3 is greater than 0.004 mm and less than 0.015 mm; wherein the width W.sub.2 of the groove formed in the central linear portion of the at least one of the first and second main surfaces of each of the first and second quartz crystal tuning fork tines is greater than 0.015 mm and less than 0.052 mm, a length of the groove formed in the central linear portion of the at least one of the first and second main surfaces of each of the first and second quartz crystal tuning fork tines being defined by l.sub.1; wherein an area S of the groove formed in the central linear portion of the at least one of the first and second main surfaces of each of the first and second quartz crystal tuning fork tines is defined by S=W.sub.2l.sub.1; and wherein the area S of the groove formed in the central linear portion of the at least one of the first and second main surfaces of each of the first and second quartz crystal tuning fork tines is greater than 0.01 mm.sup.2 and less than 0.043 mm.sup.2.
50. A quartz crystal oscillator according to claim 47; wherein the quartz crystal tuning fork base has a first base portion including a first length and a first width W.sub.5, a second base portion including a second length l.sub.4 and a second width W.sub.6 equal to the first width W.sub.5, and two cut portions formed between the first and second base portions, each of the first and second quartz crystal tuning fork tines being connected to the first base portion of the quartz crystal tuning fork base, the first length of the first base portion being within a range of 0.025 mm to 0.13 mm, and the first width W.sub.5 of the first base portion being within a range of 0.25 mm to 0.38 mm; wherein the length of the quartz crystal tuning fork base is defined by l.sub.2; wherein when a length l.sub.5 is defined by l.sub.5=l.sub.2l.sub.4, the second length l.sub.4 is less than or equal to the length l.sub.5 and is within a range of 0.05 mm to 0.3 mm; wherein a first frame portion is connected to the second base portion of the quartz crystal tuning fork base through a first connecting portion and a second frame portion is connected to the second base portion of the quartz crystal tuning fork base through a second connecting portion so that the second base portion of the quartz crystal tuning fork base and the first and second connecting portions have a concave shape or a U-shape with the first and second frame portions, a width of each of the first and second connecting portions being within a range of 0.021 mm to 0.125 mm; wherein the case has first and second mounting portions; wherein the first frame portion is mounted on the first mounting portion of the case and the second frame portion is mounted on the second mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
51. A quartz crystal oscillator according to claim 50; wherein each of the first and second frame portions has a width; and wherein the width of each of the first and second connecting portions is greater than or equal to the width of each of the first and second frame portions.
52. A quartz crystal oscillator according to claim 50; wherein the quartz crystal tuning fork base has a third base portion including a third length and a third width so that the third base portion is formed between the first and second base portions, and the third width of the third base portion is less than each of the first width W.sub.5 of the first base portion and the second width W.sub.6 of the second base portion, the third width of the third base portion being within a range of 0.1 mm to 0.2 mm; wherein the first length of the first base portion is defined by l.sub.6 and the third length of the third base portion is defined by l.sub.7; wherein a ratio l.sub.6/l.sub.7 of the first length l.sub.6 of the first base portion and the third length l.sub.7 of the third base portion is defined by l.sub.67=l.sub.6/l.sub.7; and wherein the ratio l.sub.67 is within a range of 0.8 to 1.05.
53. A quartz crystal oscillator according to claim 46; wherein each of the first and second quartz crystal tuning fork tines comprises a plurality of vibrational portions having a first vibrational portion including the first width and a first length, and a second vibrational portion including the second width greater than the first width and a second length less than the first length, the first vibrational portion of each of the first and second quartz crystal tuning fork tines having a first main surface and a second main surface opposite the first main surface; wherein each of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines has a central linear portion; and wherein the at least one groove comprises a groove formed in the central linear portion of at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines so that a width W.sub.2 of the groove formed in the central linear portion of the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is less than 0.07 mm, a first distance in the width direction of the groove measured from a first outer edge of the groove to a first outer edge of the corresponding one of the first and second quartz crystal tuning fork tines being defined by W.sub.1 and a second distance in the width direction of the groove measured from a second outer edge opposite the first outer edge of the groove to a second outer edge opposite the first outer edge of the corresponding one of the first and second quartz crystal tuning fork tines being defined by W.sub.3, and so that each of the first distance WI and the second distance W.sub.3 is less than 0.015 mm; wherein an overall length of the quartz crystal tuning fork resonator is less than 2.18 mm; and wherein a length of the quartz crystal tuning fork base is less than 0.5 mm.
54. A quartz crystal oscillator according to claim 53; wherein the overall length of the quartz crystal tuning fork resonator is within a range of 0.8 mm to 1.2 mm; wherein the width W.sub.2 of the groove formed in the central linear portion of the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.015 mm and less than 0.04 mm; wherein a length of the groove formed in the central linear portion of the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is within a range of 0.28 mm to 0.52 mm; wherein the quartz crystal tuning fork base has a first base portion including a first width, and a second base portion including a second length and a second width greater than the first width, the second length of the second base portion of the quartz crystal tuning fork base being within a range of 0.05 mm to 0.3 mm, the second width of the second base portion of the quartz crystal tuning fork base being within a range of 0.32 mm to 0.5 mm; wherein the case has a mounting portion; wherein the second base portion of the quartz crystal tuning fork base is mounted on the mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
55. A quartz crystal oscillator according to claim 53; wherein each of the first distance W.sub.1 and the second distance W.sub.3 is greater than 0.001 mm and less than 0.0035 mm; wherein a length of the groove formed in the central linear portion of the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is within a range of 0.28 mm to 0.52 m; wherein the quartz crystal tuning fork base has a first base portion including a first width, and a second base portion including a second length and a second width greater than the first width, the second length of the second base portion of the quartz crystal tuning fork base being within a range of 0.05 mm to 0.3 mm; wherein the case has a mounting portion; wherein the second base portion of the quartz crystal tuning fork base is mounted on the mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
56. A quartz crystal oscillator according to claim 53; wherein the overall length of the quartz crystal tuning fork resonator is within a range of 0.8 mm to 1.2 mm; wherein the second length of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.2 mm and less than 0.7 mm; wherein the width W.sub.2 of the groove formed in the central linear portion of the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.015 mm and less than 0.052 mm; wherein the quartz crystal tuning fork base has a first base portion including a first width W.sub.5 and a first length, a second base portion including a second width W.sub.6 greater than or equal to the first width W.sub.5 and a second length less than the first length, and two cut portions formed between the first and second base portions, each of the first and second quartz crystal tuning fork tines being connected to the first base portion of the quartz crystal tuning fork base; wherein a first frame portion is connected to the second base portion of the quartz crystal tuning fork base through a first connecting portion and a second frame portion is connected to the second base portion of the quartz crystal tuning fork base through a second connecting portion so that the second base portion of the quartz crystal tuning fork base and the first and second connecting portions have a concave shape or a U-shape with the first and second frame portions, each of the first and second frame portions having a width and a length, and each of the first and second connecting portions having a width; wherein the length of each of the first and second frame portions is within a range of 0.25 mm to 0.85 mm and the width of each of the first and second connecting portions is within a range of 0.021 mm to 0.125 mm; and wherein the width of each of the first and second frame portions is less than or equal to the first width of the first vibrational portion of each of the first and second quartz crystal tuning fork tines.
57. A quartz crystal oscillator according to claim 53; wherein the second vibrational portion of each of the first and second quartz crystal tuning fork tines comprises a plurality of portions having a first portion including a third width and a third length, and a second portion including a fourth width greater than the third width and a fourth length greater than the third length; wherein the first portion of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is formed between the second portion of the second vibrational portion of the corresponding one of the first and second quartz crystal tuning fork tines and the first vibrational portion of the corresponding one of the first and second quartz crystal tuning fork tines, the third width of the first portion being greater than 0.04 mm and less than 0.15 mm, the fourth width of the second portion being greater than 0.15 mm and less than 0.23 mm, the third length of the first portion being greater than 0.03 mm and less than 0.15 mm, and the fourth length of the second portion being greater than 0.18 mm and less than 0.45 mm; wherein the quartz crystal tuning fork base has a first base portion including a first length and a first width W.sub.5, a second base portion including a second length less than the first length and a second width W.sub.6 greater than or equal to the first width W.sub.5, and a third base portion including a third length and a third width less than each of the first width W.sub.5 and the second width W.sub.5, the third base portion being formed between the first and second base portions, the second base portion being connected to the first base portion through the third base portion, the first width W.sub.5 of the first base portion being within a range of 0.25 mm to 0.38 mm, the first length of the first base portion being within a range of 0.025 mm to 0.13 mm, the second width W.sub.6 of the second base portion being within a range of 0.25 mm to 0.52 mm, and the second length of the second base portion being within a range of 0.02 mm to 0.072 mm, each of the first and second quartz crystal tuning fork tines being connected to the first base portion of the quartz crystal tuning fork base; wherein a first frame portion is connected to the second base portion of the quartz crystal tuning fork base through a first connecting portion and a second frame portion is connected to the second base portion of the quartz crystal tuning fork base through a second connecting portion so that the second base portion of the quartz crystal tuning fork base and the first and second connecting portions have a concave shape or a U-shape with the first and second frame portions; wherein the case has first and second mounting portions; wherein the first frame portion is mounted on the first mounting portion of the case and the second frame portion is mounted on the second mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
58. A quartz crystal oscillator according to claim 53; wherein the quartz crystal tuning fork base has a first base portion, a second base portion including a first portion and a second portion, and a cut portion formed between the first base portion and the first portion of the second base portion, each of the first and second quartz crystal tuning fork tines being connected to the first base portion of the quartz crystal tuning fork base; wherein a width of the first base portion of the quartz crystal tuning fork base is within a range of 0.25 mm to 0.43 mm and a length of the first base portion of the quartz crystal tuning fork base is within a range of 0.025 mm to 0.15 mm; wherein each of the first and second portions of the second base portion of the quartz crystal tuning fork base has a width and a side surface, the side surface of the first portion of the second base portion being connected to the side surface of the second portion of the second base portion; wherein the width of the first portion of the second base portion of the quartz crystal tuning fork base is less than the width of the first base portion of the quartz crystal tuning fork base and is within a range of 0.18 mm to 0.285 mm, and the width of the second portion of the second base portion of the quartz crystal tuning fork base is within a range of 0.035 mm to 0.125 mm; wherein the case has first and second mounting portions; wherein the first portion of the second base portion of the quartz crystal tuning fork base is mounted on the first mounting portion of the case and the second portion of the second base portion of the quartz crystal tuning fork base is mounted on the second mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
59. A quartz crystal oscillator according to claim 46; wherein each of the first and second quartz crystal tuning fork tines comprises a plurality of vibrational portions having a first vibrational portion including the first width and a first length, and a second vibrational portion including the second width greater than the first width and a second length less than the first length, the second length of the second vibrational portion of each of the first and second quartz crystal tuning fork tines being greater than 0.2 mm and less than 0.7 mm, the first vibrational portion of each of the first and second quartz crystal tuning fork tines having a first main surface and a second main surface opposite the first main surface; and wherein the at least one groove comprises a groove formed in at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines so that a width of the groove formed in the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is less than 0.07 mm and a distance in the width direction of the groove measured from an outer edge of the groove to an outer edge of the corresponding one of the first and second quartz crystal tuning fork tines is less than 0.015 mm; wherein an overall length of the quartz crystal tuning fork resonator is within a range of 1.2 mm to 2 mm; wherein a length of the quartz crystal tuning fork base is less than 0.5 mm; wherein the quartz crystal tuning fork base has a first base portion including a first width, and a second base portion including a second width greater than the first width and a second length, the second width of the second base portion being within a range of 0.32 mm to 0.5 mm, and the second length of the second base portion being within a range of 0.05 mm to 0.3 mm; wherein the case has a mounting portion; wherein the second base portion of the quartz crystal tuning fork base is mounted on the mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
60. An electronic apparatus comprising: a display portion; and a quartz crystal oscillator comprised of a plurality of capacitors, a resistor and a quartz crystal unit having a case, a quartz crystal tuning fork resonator and a lid; wherein the quartz crystal tuning fork resonator has a quartz crystal tuning fork base, and first and second quartz crystal tuning fork tines connected to the quartz crystal tuning fork base, each of the first and second quartz crystal tuning fork tines comprising a plurality of different widths having a first width and a second width greater than the first width, each of the first and second quartz crystal tuning fork tines having a first main surface and a second main surface opposite the first main surface; wherein at least one groove is formed in at least one of the first and second main surfaces of each of the first and second quartz crystal tuning fork tines so that a distance in the width direction of the at least one groove measured from an outer edge of the at least one groove to an outer edge of the corresponding one of the first and second quartz crystal tuning fork tines is less than 0.021 mm; wherein the first width of each of the first and second quartz crystal tuning fork tines is greater than 0.03 mm and less than 0.075 mm and the second width of each of the first and second quartz crystal tuning fork tines is greater than 0.04 mm and less than 0.23 mm; and wherein an output signal of the quartz crystal oscillator comprising the quartz crystal unit having the quartz crystal tuning fork resonator is a clock signal for use in operation of the electronic apparatus to display time information at the display portion.
61. An electronic apparatus according to claim 60; wherein an overall length of the quartz crystal tuning fork resonator is within a range of 1.2 mm to 2 mm; wherein each of the first and second main surfaces of each of the first and second quartz crystal tuning fork tines has a central linear portion; and wherein the at least one groove comprises a groove formed in the central linear portion of at least one of the first and second main surfaces of each of the first and second quartz crystal tuning fork tines so that a width W.sub.2 of the groove formed in the central linear portion of the at least one of the first and second main surfaces of each of the first and second quartz crystal tuning fork tines is less than 0.07 mm, a first distance in the width direction of the groove measured from a first outer edge of the groove to a first outer edge of the corresponding one of the first and second quartz crystal tuning fork tines being defined by W.sub.1 and a second distance in the width direction of the groove measured from a second outer edge opposite the first outer edge of the groove to a second outer edge opposite the first outer edge of the corresponding one of the first and second quartz crystal tuning fork tines being defined by W.sub.3, and so that each of the first distance W.sub.1 and the second distance W.sub.3 is less than 0.015 mm; wherein a length of the quartz crystal tuning fork base is less than 0.5 mm; wherein the quartz crystal tuning fork base has a first base portion including a first width W.sub.5, a second base portion including a second length l.sub.4 and a second width W.sub.6 equal to the first width W.sub.5, and two cut portions formed between the first and second base portions, each of the first and second quartz crystal tuning fork tines being connected to the first base portion of the quartz crystal tuning fork base; wherein the length of the quartz crystal tuning fork base is defined by l.sub.2; wherein when a length l.sub.5 is defined by l.sub.5=l.sub.2l.sub.4, the second length l.sub.4 is less than or equal to the length l.sub.5 and is within a range of 0.05 mm to 0.3 mm; wherein a first frame portion is connected to the second base portion of the quartz crystal tuning fork base through a first connecting portion and a second frame portion is connected to the second base portion of the quartz crystal tuning fork base through a second connecting portion so that the second base portion of the quartz crystal tuning fork base and the first and second connecting portions have a concave shape or a U-shape with the first and second frame portions, a width of each of the first and second connecting portions being within a range of 0.021 mm to 0.125 mm; wherein the case has first and second mounting portions; wherein the first frame portion is mounted on the first mounting portion of the case and the second frame portion is mounted on the second mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
62. An electronic apparatus according to claim 60; wherein an overall length of the quartz crystal tuning fork resonator is within a range of 1.2 mm to 2 mm; wherein a length of the quartz crystal tuning fork base is less than 0.5 mm; wherein each of the first and second quartz crystal tuning fork tines comprises a plurality of vibrational portions having a first vibrational portion including the first width and a first length, and a second vibrational portion including the second width greater than the first width and a second length less than the first length, the second length of the second vibrational portion of each of the first and second quartz crystal tuning fork tines being greater than 0.2 mm and less than 0.7 mm, the first vibrational portion of each of the first and second quartz crystal tuning fork tines having a first main surface and a second main surface opposite the first main surface; wherein the at least one groove comprises a groove formed in at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines so that a width of the groove formed in the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is less than 0.07 mm, a first distance in the width direction of the groove measured from a first outer edge of the groove to a first outer edge of the corresponding one of the first and second quartz crystal tuning fork tines being defined by W.sub.1 and a second distance in the width direction of the groove measured from a second outer edge opposite the first outer edge of the groove to a second outer edge opposite the first outer edge of the corresponding one of the first and second quartz crystal tuning fork tines being defined by W.sub.3, and so that the first distance W.sub.1 is less than 0.015 mm and the second distance W.sub.3 is greater than the first distance W.sub.1; wherein the quartz crystal tuning fork base has a first base portion including a first width, and a second base portion including a second width greater than the first width and a second length, the second width of the second base portion being within a range of 0.32 mm to 0.5 mm, and the second length of the second base portion being within a range of 0.05 mm to 0.3 mm; wherein the case has a mounting portion; wherein the second base portion of the quartz crystal tuning fork base is mounted on the mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
63. An electronic apparatus according to claim 60; wherein each of the first and second quartz crystal tuning fork tines comprises a plurality of vibrational portions having a first vibrational portion including the first width and a first length, and a second vibrational portion including the second width greater than the first width and a second length less than the first length, the first vibrational portion of each of the first and second quartz crystal tuning fork tines having a first main surface and a second main surface opposite the first main surface; wherein each of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines has a central linear portion; and wherein the at least one groove comprises a groove formed in the central linear portion of at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines so that a width W.sub.2 of the groove formed in the central linear portion of the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is less than 0.07 mm, a first distance in the width direction of the groove measured from a first outer edge of the groove to a first outer edge of the corresponding one of the first and second quartz crystal tuning fork tines being defined by W.sub.1 and a second distance in the width direction of the groove measured from a second outer edge opposite the first outer edge of the groove to a second outer edge opposite the first outer edge of the corresponding one of the first and second quartz crystal tuning fork tines being defined by W.sub.3, and so that each of the first distance W.sub.1 and the second distance W.sub.3 is less than 0.015 mm; wherein an overall length of the quartz crystal tuning fork resonator is less than 2.18 mm; and wherein a length of the quartz crystal tuning fork base is less than 0.5 mm.
64. An electronic apparatus according to claim 63; wherein the overall length of the quartz crystal tuning fork resonator is within a range of 0.8 mm to 1.2 mm; wherein the width W.sub.2 of the groove formed in the central linear portion of the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.015 mm and less than 0.04 mm; wherein a length of the groove formed in the central linear portion of the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is within a range of 0.28 mm to 0.52 mm; wherein each of the first distance W.sub.1 and the second distance W.sub.3 is greater than 0.001 mm and less than 0.0035 mm; wherein the quartz crystal tuning fork base has a first base portion including a first width, and a second base portion including a second length and a second width greater than the first width, the second length of the second base portion of the quartz crystal tuning fork base being within a range of 0.05 mm to 0.3 mm, the second width of the second base portion of the quartz crystal tuning fork base being within a range of 0.32 mm to 0.5 mm; wherein the case has a mounting portion; wherein the second base portion of the quartz crystal tuning fork base is mounted on the mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
65. An electronic apparatus according to claim 63; wherein the overall length of the quartz crystal tuning fork resonator is within a range of 0.8 mm to 1.2 mm; wherein the second length of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.2 mm and less than 0.7 mm; wherein the width W.sub.2 of the groove formed in the central linear portion of the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.015 mm and less than 0.052 mm; wherein the second vibrational portion of each of the first and second quartz crystal tuning fork tines comprises a plurality of portions having a first portion including a third width and a third length, and a second portion including a fourth width greater than the third width and a fourth length greater than the third length; wherein the first portion of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is formed between the second portion of the second vibrational portion of the corresponding one of the first and second quartz crystal tuning fork tines and the first vibrational portion of the corresponding one of the first and second quartz crystal tuning fork tines, the third width of the first portion being greater than 0.04 mm and less than 0.15 mm, the third length of the first portion being greater than 0.03 mm and less than 0.15 mm, the fourth width of the second portion being greater than 0.15 mm and less than 0.23 mm, and the fourth length of the second portion being greater than 0.18 mm and less than 0.45 mm; wherein the quartz crystal tuning fork base has a first base portion including a first length and a first width W.sub.5, a second base portion including a second length less than the first length and a second width W.sub.6 greater than or equal to the first width W.sub.5, and a third base portion including a third length and a third width less than each of the first width W.sub.5 and the second width W.sub.6, the third base portion being formed between the first and second base portions, the second base portion being connected to the first base portion through the third base portion, the first width W.sub.5 of the first base portion being within a range of 0.25 mm to 0.38 mm, the first length of the first base portion being within a range of 0.025 mm to 0.13 mm, the second width W.sub.6 of the second base portion being within a range of 0.25 mm to 0.52 mm, and the second length of the second base portion being within a range of 0.02 mm to 0.072 mm, each of the first and second quartz crystal tuning fork tines being connected to the first base portion of the quartz crystal tuning fork base; wherein a first frame portion is connected to the second base portion of the quartz crystal tuning fork base through a first connecting portion and a second frame portion is connected to the second base portion of the quartz crystal tuning fork base through a second connecting portion so that the second base portion of the quartz crystal tuning fork base and the first and second connecting portions have a concave shape or a U-shape with the first and second frame portions, each of the first and second frame portions having a width and a length, and each of the first and second connecting portions having a width; wherein the length of each of the first and second frame portions is within a range of 0.25 mm to 0.85 mm and the width of each of the first and second connecting portions is within a range of 0.021 mm to 0.125 mm; wherein the width of each of the first and second frame portions is less than or equal to the first width of the first vibrational portion of each of the first and second quartz crystal tuning fork tines; wherein the case has first and second mounting portions; wherein the first frame portion is mounted on the first mounting portion of the case and the second frame portion is mounted on the second mounting portion of the case; and wherein the lid is connected to the case Lu cover an open end of the case.
66. An electronic apparatus according to claim 63; wherein the width of the groove formed in the central linear portion of the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.015 mm and less than 0.052 mm; wherein a length of the groove formed in the central linear portion of the at least one of the first and second main surfaces of the first vibrational portion of each of the first and second quartz crystal tuning fork tines is within a range of 0.32 mm to 0.68 mm; wherein the second length of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.2 mm and less than 0.7 mm; wherein the second width of the second vibrational portion of each of the first and second quartz crystal tuning fork tines is greater than 0.04 mm and less than 0.23 mm; wherein each of the first distance W.sub.1 and the second distance W.sub.3 is greater than 0.001 mm and less than 0.006 mm; wherein the quartz crystal tuning fork base has a first base portion, a second base portion including a first portion and a second portion, and a cut portion formed between the first base portion and the first portion of the second base portion, each of the first and second quartz crystal tuning fork tines being connected to the first base portion of the quartz crystal tuning fork base; wherein a width of the first base portion of the quartz crystal tuning fork base is within a range of 0.27 mm to 0.35 mm and a length of the first base portion of the quartz crystal tuning fork base is within a range of 0.025 mm to 0.15 mm; wherein each of the first and second portions of the second base portion of the quartz crystal tuning fork base has a width and a side surface, the side surface of the first portion of the second base portion being connected to the side surface of the second portion of the second base portion; wherein the width of the first portion of the second base portion of the quartz crystal tuning fork base is less than the width of the first base portion of the quartz crystal tuning fork base and is within a range of 0.18 mm to 0.285 mm, and the width of the second portion of the second base portion of the quartz crystal tuning fork base is within a range of 0.035 mm to 0.125 mm; wherein the case has first and second mounting portions; wherein the first portion of the second base portion of the quartz crystal tuning fork base is mounted on the first mounting portion of the case and the second portion of the second base portion of the quartz crystal tuning fork base is mounted on the second mounting portion of the case; and wherein the lid is connected to the case to cover an open end of the case.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
(33) Referring now to the drawings, the embodiments of the present invention will be described in more detail.
(34)
(35) As shown in
(36) In this embodiment, though the facsimile apparatus is shown as an example of an electronic apparatus, the present invention is not limited to this, namely, the present invention includes all electronic apparatus, each of which comprises an oscillator, e.g. a quartz crystal oscillator and a display portion at least, for example, cellar phones, telephones, a TV set, cameras, a video set, video cameras, pagers, personal computers, printers, CD players, MD players, electronic musical instruments, car navigators, car electronics, timepieces, IC cards and so forth. In other words, this invention includes electronic apparatuses comprising two of the cellar phones, the telephones, the TV set, the cameras, the video set, the video cameras, the pagers, the personal computers, the printers, the CD players, the MD players, the electronic musical instruments, the car navigators, the car electronics, the timepieces, the IC cards and so forth, and the two is connected electrically each other. For example, one of the personal computer, the camera and the video camera is electrically connected to the printer, and an output signal of the corresponding one of the personal computer, the camera and the video camera is a clock signal for use in operation of the printer. In addition, the electronic apparatus of the present invention may comprise a battery (cell), e.g. a lithium battery or a fuel cell which is housed in the electronic apparatus of the present invention. In particular, the fuel cell may be used to charge a battery housed in the electronic apparatus of the present invention through a connecting terminal.
(37)
(38) In detail, an oscillation frequency of the fundamental mode vibration is outputted through a buffer circuit as an output signal. According to the present invention, a nominal frequency of the fundamental mode vibration of the resonator is within a range of 10 kHz to 200 kHz. Especially, 32.768 kHz is an important frequency. In general, the output signal has an oscillation frequency which is within a range of 100 PPM to +100 PPM to the nominal frequency, e.g. 32.768 kHz. In more detail, the quartz crystal oscillator in this embodiment comprises a quartz crystal oscillating circuit and a buffer circuit, namely, the quartz crystal oscillating circuit comprises an amplification circuit and a feedback circuit, and the amplification circuit comprises an amplifier and a feedback resistor, and the feedback circuit comprises a flexural mode, quartz crystal tuning fork resonator, a drain resistor and capacitors. Also, flexural mode, quartz crystal tuning fork resonators which are used in a quartz crystal oscillator will be described in
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(40) In addition, load capacitance C.sub.L is given by C.sub.L=C.sub.gC.sub.d/(C.sub.g+C.sub.d), and when C.sub.g=C.sub.d=C.sub.gd and R.sub.d>>R.sub.ei, the feedback rate .sub.i is given by .sub.i=1/(1+kC.sub.L.sup.2), where k is expressed by a function of .sub.i, R.sub.d and R.sub.ei. Also, R.sub.ei is approximately equal to series resistance R.sub.i.
(41) Thus, it is easily understood from a relationship of the feedback rate .sub.i and load capacitance C.sub.L that the feedback rate of resonance frequency for a fundamental mode vibration and an overtone mode vibration becomes large, respectively, according to decrease of load capacitance C.sub.L. Therefore, when C.sub.L has a small value, an oscillation of the overtone mode occurs very easily, instead of that of the fundamental mode. This is the reason why the maximum amplitude of the overtone mode vibration becomes smaller than that of the fundamental mode vibration, and the oscillation of the overtone mode satisfies an amplitude condition and a phase condition simultaneously which are the continuous condition of an oscillation in an oscillating circuit.
(42) As it is also one object of the present invention to provide a quartz crystal oscillator having a flexural mode, quartz crystal tuning fork resonator, capable of vibrating in a fundamental mode and having a high frequency stability (high time accuracy) of an output signal, and having reduced electric current consumption, in this embodiment, load capacitance C.sub.L is less than 25 pF to reduce electric current consumption. To get much reduced electric current consumption, C.sub.L is preferably less than 15 pF because electric current consumption is proportional to C.sub.L.
(43) In addition, in order to suppress a second overtone mode vibration and to obtain a quartz crystal oscillator having an output signal of an oscillation frequency of a fundamental mode vibration, the quartz crystal oscillator in this embodiment is constructed so that it satisfies a relationship of .sub.1/a.sub.2>.sub.2/.sub.1 and .sub.1.sub.1>1, where .sub.1 and .sub.2 are, respectively, an amplification rate of the fundamental mode vibration and the second overtone mode vibration of an amplification circuit, and .sub.1 and .sub.2 are, respectively, a feedback rate of the fundamental mode vibration and the second overtone mode vibration of a feedback circuit.
(44) In other words, the quartz crystal oscillator is constructed so that a ratio of the amplification rate .sub.1 of the fundamental mode vibration and the amplification rate .sub.2 of the second overtone mode vibration of the amplification circuit is larger than that of the feedback rate .sub.2 of the second overtone mode vibration and the feedback rate .sub.1 of the fundamental mode vibration of the feedback circuit, and also a product of the amplification rate .sub.1 and the feedback rate .sub.1 of the fundamental mode vibration is larger than 1. A description of the high frequency stability will be performed later.
(45) Also, characteristics of the amplifier of the amplification circuit constructing the quartz crystal oscillating circuit of this embodiment can be expressed by negative resistance RL.sub.i. For example, when i=1, negative resistance RL.sub.1 is for a fundamental mode vibration and when i=2, negative resistance RL.sub.2 is for a second overtone mode vibration. In this embodiment, the quartz crystal oscillating circuit is constructed so that a ratio of an absolute value of negative resistance, |RL.sub.1| of the fundamental mode vibration of the amplification circuit and series resistance R.sub.1 of the fundamental mode vibration is larger than that of an absolute value of negative resistance, |RL.sub.2| of the second overtone mode vibration of the amplification circuit and series resistance R.sub.2 of the second overtone mode vibration. That is to say, the oscillating circuit is constructed so that it satisfies a relationship of |RL.sub.1|/R.sub.1>|RL.sub.2|/R.sub.2. By constructing the oscillating circuit like this, an oscillation of the second overtone mode can be suppressed, as a result of which an output signal of a frequency of the fundamental mode vibration can be provided because an oscillation of the fundamental mode generates easily in the oscillating circuit.
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(48) Furthermore, the grooves 21 and 22 have the first electrodes 23 and 24 both of the same electrical polarity, the grooves 32 and 33 have the second electrodes 34 and 35 both of the same electrical polarity, the grooves 36 and 37 have the third electrodes 38 and 39 both of the same electrical polarity, the grooves 27 and 28 have the fourth electrodes 29 and 30 both of same electrical polarity and the sides of the base 40 have the fifth and sixth electrodes 25 and 31, each of opposite electrical polarity. In more detail, the fifth, fourth, and second electrodes 25, 29, 30, 34 and 35 have the same electrical polarity, while the first, sixth and third electrodes 23, 24, 31, 38 and 39 have the opposite electrical polarity to the others. Two electrode terminals E and E are constructed. That is, the electrodes disposed inside the grooves constructed opposite each other in the thickness (z axis) direction have the same electrical polarity. Also, the electrodes disposed opposite each other across adjoining grooves have opposite electrical polarity.
(49) In addition, the resonator has a thickness t of the tines or the tines and the base, and a groove thickness t.sub.1. It is needless to say that the electrodes are disposed inside the grooves and on the sides of the tines. In this embodiment, the first electrodes 23 and 24 are disposed at the tine and the base, and also, the fourth electrodes 29 and 30 are disposed at the tine and the base. In addition, the electrodes are disposed on the sides of the tines opposite each other to the electrodes disposed inside the grooves. Namely, the electrodes are disposed opposite each other inside the grooves and on the sides of the tines so that the electrodes disposed opposite each other are of opposite electrical polarity. Additionally, electrodes are disposed facing each other on the sides of the tines so that the electrodes disposed facing each other are of opposite electrical polarity, and the tines are capable of vibrating in inverse phase. In more detail, a first tuning fork tine and a second tuning fork tine, and a tuning fork base are formed integrally, an electrode is disposed on both sides of the first tine and the second tine so that the electrodes disposed (facing each other) on inner sides of the first and second tines are of opposite electrical polarity. Therefore, the disposition of the electrodes disposed inside the grooves and on the sides of the tuning fork tines, described above is the same as that of the electrodes shown in
(50) When a direct current voltage is applied between the electrode terminals E and E (E terminal: plus, E terminal: minus), an electric field E.sub.x occurs in the arrow direction as shown in
(51)
(52) In more detail, when part widths W.sub.1, W.sub.3 and a groove width W.sub.2 are taken, the tine width W of the tines 20 and 26 has a relationship of W=W.sub.1+W.sub.2+W.sub.3, and the part widths W.sub.1,W.sub.3 are constructed so that W.sub.1W.sub.3 or W.sub.1<W.sub.3. In addition, the groove width W.sub.2 is constructed so that W.sub.2W.sub.1, W.sub.3. In this embodiment, also, the grooves are constructed at the tines so that a ratio (W.sub.2/W) of the groove width W.sub.2 and the tine width W is larger than 0.35 and less than 1, preferably larger than 0.35 and less than 0.85, and a ratio (t.sub.1/t) of the groove thickness t.sub.1 and the thickness t of the tines (tine thickness t) is less than 0.79, preferably, larger than 0.05 and less than 0.79, more preferably, larger than 0.1 and less than 0.6 to obtain very large moment of inertia of the tines and a small motional inductance L.sub.1 of the fundamental mode of vibration. In more detail, when each of the grooves 21 and 27 formed in the obverse faces of the tines 20 and 26 has a depth t.sub.1 and each of the grooves 22 and 28 formed in the reverse faces of the tines 20 and 26 has a depth t.sub.2, the thickness t is given by t=t.sub.1+t.sub.2+t.sub.3, and t.sub.1 and t.sub.2 are larger than 0.021 mm, preferably, larger than 0.025 mm and less than 0.075 mm, more preferably, larger than 0.03 mm and less than 0.055 mm. That is, the flexural mode, quartz crystal tuning fork resonator, capable of vibrating in the fundamental mode, and having a good frequency stability can be provided with a small series resistance R.sub.1, a high quality factor Q.sub.1 and a small capacitance ratio r.sub.1 because electromechanical transformation efficiency of the resonator becomes large markedly.
(53) Likewise, a length l.sub.1 of the grooves 21, 27 provided at the tines 20, 26 extends into the base 40 in this embodiment (which has a dimension of the length l.sub.2 and the length l.sub.3 of the grooves). Therefore, a groove length and a length of the tines are given by (l.sub.1l.sub.3) and (ll.sub.2), respectively, and a ratio of (l.sub.1l.sub.3) and (ll.sub.2) is within a range of 0.3 to 0.8, preferably, 0.4 to 0.8 to get a flexural mode tuning fork resonator with series resistance R.sub.1 of a fundamental mode vibration smaller than series resistance R.sub.2 of a second overtone mode vibration. In other words, a groove length is within a range of 30% to 80%, preferably, 40% to 80% of a length of each of the tines, so that a flexural mode tuning fork resonator with a reduced series resistance R.sub.1 and a small motional inductance L.sub.1 of a fundamental mode vibration and having shock proof can be obtained when the flexural mode tuning fork resonator is miniaturized. Also, a length l.sub.2 of the base is less than 0.5 mm, preferably, within a range of 0.29 mm to 0.48 mm or within a range of 0.12 mm to 0.255 mm or within a range of 0.264 mm to 0.277 mm, more preferably, within a range of 0.05 mm to 0.178 mm or within a range of 0.08 mm to 0.17 mm or within a range of 0.1 mm to 0.165 mm, so that a much miniaturized flexural mode tuning fork resonator can be obtained with reduced energy losses which are caused by vibration when it is mounted on a mounting portion of a case. As be well known, the resonator can be expressed by an electrical equivalent circuit comprising motional capacitance C.sub.1, motional inductance L.sub.1, series resistance R.sub.1 connected in series, and shunt capacitance C.sub.0 connected to C.sub.1, L.sub.1 and R.sub.1 in parallel.
(54) Furthermore, the total length l is determined by the frequency requirement and the size of the housing case. Simultaneously, to get a flexural mode, quartz crystal tuning fork resonator, capable of vibrating in a fundamental mode with suppression of the second overtone mode vibration which is an unwanted mode vibration, there is a close relationship between the groove length l.sub.1 and the total length l. Namely, a ratio (l.sub.1/l) of the groove length l.sub.1 and the total length l is within a range of 0.2 to 0.78 because the quantity of charges which generate within the grooves and on the sides of the tines or the tines and the base can be controlled by the ratio, as a result, the second overtone mode vibration which is an unwanted mode vibration, can be suppressed, and simultaneously, a frequency stability of the fundamental mode vibration gets high. Therefore, the flexural mode, quartz crystal tuning fork resonator, capable of vibrating easily in a fundamental mode and having high frequency stability can be provided.
(55) Also, the total length l is less than 2.18 mm, preferably, within a range of 1.2 mm to 2 mm, more preferably, 0.8 mm to 1.2 mm, and groove length l.sub.1 is less than 1.29 mm, preferably, within a range of 0.32 mm to 1.1 mm, more preferably, within a range of 0.32 mm to 0.85 mm, to get a smaller-sized tuning fork resonator with about 32.768 kHz and a small motional inductance L.sub.1 which vibrates in a flexural mode and a fundamental mode. In addition, to get a very much smaller-sized tuning fork resonator width energy losses reduced, which are caused by vibration, a small series resistance R.sub.1 and a small motional inductance L.sub.1, the total length l is within a range of 0.65 mm to 0.98 mm, and the groove length l.sub.1 is within a range of 0.32 mm to 0.68 mm or within a range of 0.28 mm to 0.52 mm.
(56) In more detail, series resistance R.sub.1 of the fundamental mode vibration becomes smaller than series resistance R.sub.2 of the second overtone mode vibration. Namely, R.sub.1<R.sub.2, preferably, R.sub.1<0.86R.sub.2, therefore, a quartz crystal oscillator comprising an amplifier (CMOS inverter), capacitors, resistors and a quartz crystal unit with the quartz crystal tuning fork resonator of this embodiment can be obtained, which is capable of vibrating in the fundamental mode easily. In addition, in this embodiment the grooves 21 and 27 of the tines 20 and 26 extend into the base 40 in series, but embodiment of the present invention includes a plurality of grooves divided into the length direction of the tines. In addition, the grooves may be constructed only at the tines (l.sub.3=0). From the relationship of l.sub.3=0, each of the grooves 21, 22, 27 and 28 has a first stepped portion and a second stepped portion opposite the first stepped portion in the width direction, and a third stepped portion and a fourth stepped portion opposite the third stepped portion in the length direction.
(57) In this embodiment, the groove length l.sub.1 corresponds to electrode length disposed inside the grooves, though the electrode is not shown in
(58) In addition, a spaced-apart distance between the tines is given by W.sub.4, and in this embodiment, the distance W.sub.4 and the groove width W.sub.2 are constructed so that W.sub.4W.sub.2, and more, the distance W.sub.4 is within a range of 0.05 mm to 0.35 mm and the groove width W.sub.2 is within a range of 0.03 mm to 0.12 mm because it is easy to form a tuning fork shape and grooves of the tuning fork tines separately by a photo-lithographic process and an etching process, consequently, a frequency stability for a fundamental mode vibration gets higher than that for a second overtone mode vibration. In this embodiment, a quartz wafer with the thickness t of 0.05 mm to 0.18 mm is used.
(59) Furthermore, in order to get a smaller-sized quartz crystal tuning fork resonator, capable of vibrating in a flexural mode, and having a small motional inductance L.sub.1, it is necessary that groove width W.sub.2 is less than 0.07 mm, preferably, larger than 0.012 mm and less than 0.043 mm or larger than 0.015 mm and less than 0.052 mm or larger than 0.015 mm and less than 0.04 mm and tine width W is less than 0.18 mm, and preferably, the W is larger than 0.05 mm and less than 0.1 mm, more preferably, larger than 0.03 mm and less than 0.075 mm.
(60) Also, a groove thickness t.sub.1 is within a range of 0.01 mm to 0.085 mm approximately, and part widths W.sub.1, W.sub.3 are less than 0.021 mm, preferably, less than 0.015 mm. In more detail, a dimension of the part widths W.sub.1, W.sub.3 is very dependent on a manufacturing technology. Therefore, when the technology is taken into account, W.sub.1 and W.sub.3 have a value of larger than 0.004 mm, preferably, larger than 0.008 mm and less than 0.015 mm, more preferably, larger than 0.01 mm and less than 0.014 mm to get a small motional inductance L.sub.1.
(61) In order to get a much smaller-sized quartz crystal tuning fork resonator with a very small series resistance R.sub.1 and a small motional inductance L.sub.1, each of the part widths W.sub.1, W.sub.3 has a value of larger than 0.001 mm (1 m) and less than 0.006 mm (6 m), preferably, larger than 0.001 mm or 0.0035 mm and less than 0.004 mm or 0.0043 mm, more preferably, larger than 0.001 mm and less than 0.0035 mm.
(62) In addition, the groove provided on at least one of the obverse face and the reverse face of the tuning fork tines of the present invention may be a through hole, namely, the groove thickness t.sub.1=0. In other words, the base 40 has two through-holes. Moreover, another example of the tuning fork tines having t.sub.1=0 is shown in
(63) In more detail, to obtain a flexural mode, quartz crystal tuning fork resonator with a high frequency stability which gives high time accuracy, it is necessary to obtain the resonator whose resonance frequency is not influenced by shunt capacitance because quartz crystal is a piezoelectric material and the frequency stability is very dependent on the shunt capacitance. In order to decrease the influence on the resonance frequency by the shunt capacitance, figure of merit M.sub.i (hereafter a merit value M.sub.i) plays an important role. Namely, the merit value M.sub.i that expresses inductive characteristics, electromechanical transformation efficiency and a quality factor of a flexural mode, quartz crystal tuning fork resonator, is defined by a ratio (Q.sub.i/r.sub.i) of a quality factor Q.sub.i and capacitance ratio r.sub.i, namely, M.sub.i is given by M.sub.i=Q.sub.i/r.sub.i, where i shows vibration order of the resonator, and for example, when i=1 and 2, the merit values M.sub.1 and M.sub.2 are a value for a fundamental mode vibration and a second overtone mode vibration of the flexural mode, quartz crystal tuning fork resonator, respectively.
(64) Also, a frequency difference f of resonance frequency f.sub.s of mechanical series independent on the shunt capacitance and resonance frequency f.sub.r dependent on the shunt capacitance is inversely proportional to the merit value M.sub.i. The larger the value M.sub.i becomes, the smaller the difference f becomes. Namely, the influence on the resonance frequency f.sub.r by the shunt capacitance decreases because it is close to the resonance frequency f.sub.s. Accordingly, the larger the M.sub.i becomes, the higher the frequency stability of the flexural mode, quartz crystal tuning fork resonator becomes because the resonance frequency f.sub.r of the resonator is almost never dependent on the shunt capacitance. Namely, the quartz crystal tuning fork resonator can be provided with a high time accuracy.
(65) In detail, the flexural mode, quartz crystal tuning fork resonator can be obtained with the merit value M.sub.1 of the fundamental mode vibration larger than the merit value M.sub.2 of the second overtone mode vibration by the above-described tuning fork shape, grooves and dimensions. That is to say, a relationship of M.sub.1>M.sub.2 is obtained. As an example, when resonance frequency of a flexural mode, quartz crystal tuning fork resonator is about 32.768 kHz for a fundamental mode vibration and the resonator has a value of W.sub.2/W=0.5, t.sub.1/t=0.34 and l.sub.1/l=0.48, though there is a distribution in production, the resonator has a value of M.sub.1>65 and M.sub.2<30, respectively.
(66) Namely, the flexural mode, quartz crystal tuning fork resonator which vibrates in the fundamental mode can be provided with high inductive characteristics, good electromechanical transformation efficiency (small capacitance ratio r.sub.1 and small series resistance R.sub.1) and a high quality factor. As a result, a frequency stability of the fundamental mode vibration becomes higher than that of the second overtone mode vibration, and simultaneously, the second overtone mode vibration can be suppressed because capacitance ratio r.sub.2 and series resistance R.sub.2 of the second overtone mode vibration become larger than capacitance ratio r.sub.1 and series resistance R.sub.1 of the fundamental mode vibration, respectively. In particular, r.sub.2 has a value larger than 1500 in this embodiment.
(67) Therefore, the resonator capable of vibrating in the fundamental mode vibration can be provided with a high time accuracy because it has the high frequency stability. Consequently, a quartz crystal oscillator comprising the flexural mode, quartz crystal tuning fork resonator of this embodiment outputs an oscillation frequency of the fundamental mode vibration as an output signal, and the frequency of the output signal has a very high stability, namely, excellent time accuracy. In other words, the quartz crystal oscillator of this embodiment has a remarkable effect such that a frequency change by ageing becomes extremely small. Also, an oscillation frequency of the resonator of this embodiment is adjusted so that a frequency deviation is within a range of 100 PPM to +100 PPM to a nominal frequency, e.g. 32.768 kHz, after mounting it at a mounting portion of a case or a lid by conductive adhesives or solder.
(68) In addition, the groove thickness t.sub.1 of the present invention is the thinnest thickness of the grooves because quartz crystal is an anisotropic material and the groove thickness t.sub.1 has a distribution when it is formed by a chemical etching method. In detail, a groove shape of the sectional view of tuning fork tines in
(69)
(70) Namely, the quartz crystal tuning fork resonator, capable of vibrating in a fundamental mode and having a high frequency stability can be provided with a small series resistance R.sub.1 and a high quality factor Q.sub.1. Therefore, a quartz crystal oscillator having the high frequency stability can be realized with an output signal of a frequency of the fundamental mode vibration. In this embodiment, though electrodes are not shown in
(71) In addition, the base 48 has cut portions 53 and 54, and the cut base 48 has a dimension of a first length and a first width W.sub.5 (tines side), and a second length l.sub.4 and a second width W.sub.6 (opposite side to the tines side). Also, the cut base 48 has the second length l.sub.4 located between one of the cut portions and the side opposite to the tines side, and the second length l.sub.4 is greater than 0.02 mm or 0.03 mm and less than 0.48 mm, preferably, within a range of 0.05 mm to 0.3 mm or 0.02 mm to 0.072 mm, more preferably, within a range of 0.025 mm to 0.04 mm or 0.12 mm to 0.25 mm to reduce energy losses which are caused by vibration. In addition, when a length l.sub.5 is defined by l.sub.5=l.sub.2l.sub.4, l.sub.4 is less than or equal to l.sub.5 to achieve the decreased energy losses. When the base 48 is mounted at a mounting portion (e.g. on two lead wires for a package of a tubular type) of a case or a lid of a surface mounting type or a tubular type by solder or conductive adhesives, it is necessary to satisfy W.sub.6W.sub.5 to decrease energy losses by vibration. The cut portions 53 and 54 are very effective to decrease the energy losses.
(72) In more detail, the base 48 has a first base portion which includes the first length and the first width W.sub.5, a second base portion which includes the second length l.sub.4 less than or equal to the first length of the first base portion and the second width W.sub.6 greater than or equal to the first width W.sub.5, and two cut portions formed between the first and second base portions. Also the first width W.sub.5 of the first base portion of the base 48 is within a range of 0.25 mm to 0.38 mm, preferably, within a range of 0.32 mm to 0.42 mm, and the first length of the first base portion of the base 48 is within a range of 0.025 mm to 0.13 mm, preferably, within a range of 0.03 mm to 0.075 mm. In addition, the second width W.sub.6 of the second base portion of the base is within a range of 0.25 mm to 0.52 mm, preferably, within a range of 0.32 mm to 0.5 mm, and as already described above, the second length of the second base portion of the base is within a range of 0.02 mm to 0.072 mm.
(73) In other words, the base 48 has the first base portion which includes the first length and the first width W.sub.5, the second base portion which includes the second length l.sub.4 less than or equal to the first length of the first base portion and the second width W.sub.6 greater than or equal to the first width W.sub.5, and a third base portion including a third width less than each of the first and second widths and a third length less than or equal to each of the first length of the first base portion and the second length l.sub.4 of the second base portion. In addition, the third length of the third base portion of the base is within a range of 0.012 mm to 0.055 mm, preferably, within a range of 0.015 mm to 0.04 mm, and the third width of the third base portion of the base is within a range of 0.04 mm to 0.125 mm, preferably, within a range of 0.05 mm to 0.094 mm. As a result of which the resonator is obtained with reduced energy losses and a small series resistance R.sub.1.
(74) In order to get the base portion 48 very strong against a shock, when a ratio of the first width W.sub.5 of the first base portion and the third width of the third base portion is defined by a first ratio, the first ratio is within a range of 1.92 to 3.4, preferably, within a range of 2.08 to 2.5 or within a range of 3.1 to 4.8. Similar to this, when a ratio of the first length of the first base portion and the third length of the third base portion is defined by a second ratio, the second ratio is within a range of 0.8 to 1.05 or within a range of 1.2 to 2.8, preferably, within a range of 1.25 to 1.8 or within a range of 1.83 to 2.6.
(75) In addition, it is needless to say that this invention includes the base 48 having a first base portion, a second base portion and a cut portion formed between the first and second base portions. In this embodiment, the second base portion has first and second portions and the cut portion is formed between the first base portion and the first portion of the second base portion. Also, each of the tuning fork tines 46, 47 is connected to the first base portion of the base, and a width of the first base portion of the base is within a range of 0.25 mm to 0.43 mm, preferably, 0.27 mm to 0.35 mm and a length of the first base portion of the base is within a range of 0.025 mm to 0.15 mm, preferably, 0.025 mm to 0.13 mm to get the base very strong against a shock.
(76) In detail, each of the first and second portions of the second base portion of the base has a width and a side surface, and the side surface of the first portion of the second base portion is connected to the side surface of the second portion of the second base portion. In order to reduce energy losses which are caused by vibration, the width of the first portion of the second base portion of the base is less than the width of the first base portion of the base and is within a range of 0.18 mm to 0.285 mm, and the width of the second portion of the second base portion of the base is within a range of 0.035 mm to 0.125 mm.
(77) Furthermore, the width of the first portion of the second base portion of the base is greater than the width of the second portion of the second base portion of the base. Also, an overall width of the second base portion of the base is defined by a summation of the width of the first portion and the width of the second portion, and the overall width of the second base portion of the base is less than or substantially equal to the width of the first base portion of the base, and is within a range of 0.215 mm to 0.41 mm. In addition, a case has first and second mounting portions, and the first portion of the second base portion of the base is mounted on the first mounting portion of the case and the second portion of the second base portion of the base is mounted on the second mounting portion of the case, and a lid is connected to the case to cover an open end of the case.
(78) In other words, the base 48 comprises the first base portion, the second base portion having the first and second portions, and a third base portion formed between the first base portion and the first portion of the second base portion so that the first base portion is connected to the first portion of the second base portion through the third base portion, and a width of the third base portion is less than each of the width of the first base portion and the width of the first portion of the second base portion, and is within a range of 0.1 mm to 0.2 mm, preferably, 0.12 mm to 0.18 mm, and so that a length of the third base portion is less than each of the length of the first base portion and a length of the second base portion which is within a range of 0.055 mm to 0.07 mm, and is within a range of 0.012 mm to 0.055 mm, preferably, within a range of 0.015 mm to 0.04 mm.
(79) As already described in
(80) In addition, as described above, the groove 49 is constructed to include a portion of the central line 51 of the tine 46, and the groove 50 is similarly constructed to include a portion of the central line 52 of the tine 47. Furthermore, each of the tines 46, 47 has an end portion including an outer edge and the base 48 has a side surface, and the end portion of each of the tines 46, 47 is connected to the side surface of the base 48, and when a distance in the length direction of the groove measured from an outer edge of the groove to the outer edge of the end portion of the tine 46 is defined by a first distance and a distance in the length direction of the groove measured from an outer edge of the groove to the outer edge of the end portion of the tine 47 is defined by a second distance, each of the first and second distances is within a range of 0.01 mm to 0.065 mm.
(81) Therefore, the flexural mode, quartz crystal tuning fork resonator, capable of vibrating in the fundamental mode and having the high frequency stability (high time accuracy) can be provided with a small series resistance R.sub.1 and a high quality factor Q.sub.1. Also, the width dimensions W=W.sub.1+W.sub.2+W.sub.3 and W.sub.4, and the length dimensions l.sub.1, l.sub.2 and l are as already described in relation to
(82) In addition, a shape of the tuning fork base according to the present invention is not limited to that of this embodiment, for example, a tuning fork base may have a frame portion protruding from the tuning fork base, and the frame portion is mounted at a mounting portion of a case or a lid of a package. The matter described above implies that, for example, when the tuning fork tines have a first tuning fork tine and a second tuning fork tine, the first tuning fork tine is between the second tuning fork tine and the frame portion protruding from the tuning fork base as shown in
(83) In more detail, the quartz crystal unit 250 comprises a quartz crystal tuning fork resonator 255 capable of vibrating in a flexural mode of an inverse phase, a case 256 for housing the resonator and a lid for covering an open end of the case (not shown here). Namely, the resonator 255 comprises tuning fork tines 257, 258 and a tuning fork base 259 connected to the tuning fork tines, and the tuning fork base 259 has a frame portion 260 protruding from the tuning fork base. Also, the case 256 has mounting portions 261 and 262, and the frame portion 260 is mounted on the mounting portion 261 of the case 256. Namely, the base 259 has a first base portion including a first width, a second base portion including a second width and at least one cut portion formed between the first and second base portions, and the frame portion 260 is connected to the second base portion of the base 259 through a connecting portion. In this embodiment, two portions of the frame portion 260 are mounted on the mounting portions 261, 262 of the case 256. However, this invention is not limited to this, but includes the frame portion mounted on the mounting portion 261 of the case 256 and the second base portion mounted on a mounting portion of the case 256.
(84) In detail, an electrode 267 disposed at the frame portion 260 is connected to an electrode 268 disposed on the mounting portion 261 by adhesives 263 or a metal such as solder, and similarly, an electrode 269 disposed on the tuning fork base 259 is connected to an electrode 270 disposed on the mounting portion 262 by adhesives 264 or a metal such as solder.
(85) In addition, the tuning fork tines 257, 258 have grooves 271, 273 (not shown here), 272 and 274 (not shown here), the grooves 271 and 272 are formed opposite to the grooves 273 and 274 in the thickness direction, respectively. The electrodes 271a and 273a disposed inside the grooves 271 and 273 of the tine 257 are connected to the electrodes 275 and 276 disposed on side surfaces of the tine 258 to define a first electrode terminal, while the electrodes 272a and 274a disposed inside the grooves 272 and 274 of the tine 258 are connected to the electrodes 277 and 278 disposed on side surfaces of the tine 257 to define a second electrode terminal.
(86) Moreover, each of the tines 257, 258 has a width W which is a first width of a first vibrational portion and a width W.sub.g which is a second width of a second vibrational portion, greater than the width W, preferably, the width W.sub.g is less than three times of the width W to get a small motional inductance L.sub.1. Namely, a ratio Wg/W of the width Wg and the width W is greater than 1 and less than 3. In addition, as is apparent from
(87) For example, when the width W is larger than 0.03 mm and less than 0.075 mm, the width W.sub.g is larger than 0.04 mm and less than 0.23 mm. For example, a difference (W.sub.gW) is within a range of 0.008 mm to 0.1 mm, preferably, 0.01 mm to 0.05 mm to get enough mass effect. Also, each of the tines 257, 258 has a length l.sub.g less than about 80% of a length of each of the tines measured from the free end of each of the tines. This is the reason why when each of the tines has the width W with a frequency, e.g. 32.8 kHz with the length l.sub.g=0, about the same frequency can be obtained as the frequency of 32.8 kHz for the width W by forming the length l.sub.g of about 80%. Namely, the tuning fork resonator can be obtained with a small motional inductance L.sub.1 because the width of the tines becomes larger actually and the electromechanical transformation efficiency gets larger.
(88) In order to get a large mass effect by the length l.sub.g, each of the tines, preferably, has the length l.sub.g less than a half of the length of each of the tines measured from the free end of each of the tines. Namely, the length l.sub.g of the second vibrational portion of each of the tines is less than a length of the first vibrational portion of each of the tines. For example, the length l.sub.g is larger than 0.15 mm and less than 1.1 mm, preferably, larger than 0.2 mm and less than 0.7 mm. In general, metal films for adjusting an oscillation frequency of the resonator are formed on main surfaces having the width W.sub.g, and the oscillation frequency is adjusted by trimming at least one of the metal films. In addition, the tuning fork base has cut portions 265, 266 and the length l.sub.4, and the frame portion is connected to the tuning fork base having the length l.sub.4.
(89) In order to reduce energy losses which are caused by vibration, a length of the frame portion is greater than 0.25 mm and less than 0.85 mm and a width of the frame portion is equal to or different from a width of the first vibrational portion of each of the tines. For example, the width of the frame portion is less than or equal to the width of the first vibrational portion of each of the tines. Also, this concept can be applied to a plurality of frame portions having first and second frame portions each connected to the tuning fork base.
(90) In addition, it is needless to say that this invention is not limited to this embodiment, but includes the second vibrational portion comprising a plurality of portions having a first portion including a third width and a third length, and a second portion including a fourth width greater than the third width and a fourth length greater the third length. In detail, the first portion of the second vibrational portion of each of the tines 257, 258 is formed between the first vibrational portion of the corresponding one of the tines 257, 258 and the second portion of the second vibrational portion of the corresponding one of the tines 257, 258.
(91) In order to get a much smaller-sized resonator with an enough mass effect, the third width of the first portion of the second vibrational portion of each of the tines 257, 258 is greater than 0.04 mm and less than 0.2 mm, preferably, greater than 0.04 mm and less than 0.15 mm and the fourth width of the second portion of the second vibrational portion of each of the tines 257, 258 is greater than 0.15 mm and less than 0.32 mm, preferably, greater than 0.15 mm and less than 0.23 mm. Also, the third length of the first portion of the second vibrational portion of each of the tines 257, 258 is greater than 0.03 mm and less than 0.25 mm, preferably, greater than 0.03 mm and less than 0.15 mm and the fourth length of the second portion of the second vibrational portion of each of the tines 257, 258 is greater than 0.16 mm and less than 0.49 mm, preferably, greater than 0.18 mm and less than 0.45 mm.
(92) In this embodiment, though the second vibrational portion comprises the first and second portions, this invention is not limited to this, but includes the second vibrational portions having a third portion, a fourth portion, a fifth portion, and more than the fifth portion each of which has a width different each other.
(93) Furthermore, in order to obtain a miniature quartz crystal unit with a length less than 1.5 mm and a width less than 1.2 mm, e.g. the length 1.2 mm and the width 1.0 mm, it is needed to obtain a very much smaller-sized resonator having an overall length less than 1.21 mm, e.g. within a range of 0.8 mm to 1.2 mm or greater than 0.6 mm and less than 0.8 mm, and also, the much smaller-sized resonator is required to have a small series resistance R.sub.1, a small motional inductance L.sub.1, a stable frequency of oscillation and reduced energy losses. In order to obtain the much smaller-sized resonator with the these conditions, a ratio W.sub.g/W of the width W.sub.g of the second vibrational portion of each of the tines and the width W of the first vibrational portion of each of the tines is substantially equal to 3.0 or greater than 3.0 and less than 6.5, preferably, greater than 3.1 and less than 6.0, more preferably, greater than 3.2 and less than 5.0.
(94) In addition, another example is shown in
(95) Namely, the resonator 355 comprises tuning fork tines 357, 358 and a tuning fork base 359 connected to the tuning fork tines, and the tuning fork base 359 has two frame portions 360a, 360b protruding from the tuning fork base. Also, the case 356 has mounting portions 361 and 362, and the frame portions 360a and 360b is, respectively, mounted on the mounting portion 361 and 362 of the case 356.
(96) In detail, an electrode 367 disposed at the frame portion 360a is connected to an electrode 368 disposed on the mounting portion 361 by adhesives 363 or a metal such as solder, and similarly, an electrode 369 disposed at the frame portion 360b is connected to an electrode 370 disposed on the mounting portion 362 by adhesives 364 or a metal such as solder. In addition, the tuning fork base has two cut portions 365 and 366, the tuning fork tines 357, 358 have the same as the grooves, the electrodes and the shape of the tuning fork tines shown in
(97) Namely, as shown in
(98) Therefore, when the width W.sub.5 of the first base portion of the tuning fork base is substantially equal to the width W.sub.6 of the second base portion of the tuning fork base, the first frame portion is connected to the second base portion of the tuning fork base 359 through a first connecting portion having a width and the second frame portion is connected to the second base portion of the tuning fork base 359 through a second connecting portion having a width so that the second base portion of the tuning fork base 359 and the first and second connecting portions have a concave shape or U-shape width the first and second frame portions, and the first and second frame portions extend in a common direction with the first and second tuning fork tines outside the first and second tuning fork tines.
(99) Similar to this, when the width W.sub.6 of the second base portion of the tuning fork base is greater than the width W.sub.5 of the first base portion of the tuning fork base, a side surface of the first frame portion is connected to a side surface of the second base portion of the tuning fork base 359 and a side surface of the second frame portion is connected to a side surface of the second base portion of the tuning fork base 359 so that the second base portion of the tuning fork base 359 has a concave shape or U-shape with the first and second frame portions, and the first and second frame portions extend in a common direction with the first and second tuning fork tines outside the first and second tuning fork tines.
(100) In order to get the resonator 355 which is a much smaller-sized tuning fork resonator with reduced energy losses, and having a stable frequency of oscillation and a small motional inductance L.sub.1, the width of each of the first and second frame portions is less than or equal to the width W of the first vibrational portion of each of the first and second tuning fork tines and is within a range of 0.02 mm to 0.055 mm, and the length of each of the first and second frame portions is within a range of 0.25 mm to 0.85 mm. Furthermore, the length of the first frame portion is substantially equal to or different from the length of the second frame portion, namely, greater than or less than the length of the second frame portion. In addition, the width of each of the first and second connecting portions is within a range of 0.021 mm to 0.125 mm and greater than or equal to the width of each of the first and second frame portions.
(101) In more detail, each of the first and second frame portions has a mounting portion including a width, and the width of each of the first and second connecting portions is greater than or equal to the width of the mounting portion of each of the first and second frame portions. Also, a case has first and second mounting portions, and the mounting portion of the first frame portion is mounted on the first mounting portion of the case and the mounting portion of the second frame portion is mounted on the second mounting portion of the case, and a lid is connected to the case to cover an open end of the case.
(102) In order to get the resonator 355 which is the much smaller-sized tuning fork resonator with an additional benefit, namely, which is very strong against a shock, when the first base portion of the tuning fork base has a length, and a ratio of the length of the first base portion of the tuning fork base and the width of each of the first and second connecting portions is defined by a length-width ratio, the length-width ratio is within a range of 0.35 to 1.07, preferably, within a range of 0.36 to 1.06 or 1.1 to 1.26.
(103) In addition, when a ratio of the width W.sub.g of the second vibrational portion of each of the tuning fork tines 357, 358 and the length of the first base portion of the tuning fork base is defined by a width-length ratio, the width-length ratio is within a range of 1.6 to 5.2, preferably, within a range of 1.8 to 4.5 or 2.1 to 4.8. In detail, when the second vibrational portion of each tuning fork tine comprises a plurality of portions each of which has a width different each other, the width W.sub.g of the second vibrational portion corresponds to a maximum width of the widths of the portions of the second vibrational portion, e.g. when the portions have a first portion including a first width and a second portion including a second width greater than the first width, the width W.sub.g corresponds to the second width.
(104) Furthermore, when a ratio of the width W.sub.g of the second vibrational portion of each of the tuning fork tines 357, 358 and the width of each of the first and second frame portions is defined by a width-width ratio, the width-width ratio is within a range of 2.3 to 5.5, preferably, within a range of 2.4 to 4.0 or 4.1 to 5.4. As described above, the base 359 has a third base portion formed between the first and second base portions, and a ratio of the width W.sub.g and a width of the third base portion of the base is within a range of 1.2 to 2.8, preferably, within a range of 1.5 to 2.5, more preferably, within a range of 1.5 to 1.65 or 1.71 to 2.5.
(105) When the quartz crystal tuning fork resonator 355 in this embodiment is formed in a quartz crystal wafer, an end portion of the frame portion 360a is not connected to an end portion of the frame portion 360b, as is shown in
(106)
(107) In addition, the electrode 64 extends to the mounting portion 81 through the one connecting portion 69 and the electrode 65 extends to the mounting portion 68 through the other connecting portion 66. In this embodiment, the electrodes 64 and 65 disposed on the vibrational portion 63 extend to the mounting portions of the different direction each other. But, the electrodes may be constructed in the same direction. The resonator in this embodiment is mounted on fixing portions of a case or a lid at the mounting portions 68 and 81 by conductive adhesives or solder.
(108) Here, a cutting angle of the length-extensional mode quartz crystal resonator is shown. First, a quartz crystal plate perpendicular to x axis, so called, X plate quartz crystal is taken. Length L.sub.0, width W.sub.0 and thickness T.sub.0 which are each dimension of the X plate quartz crystal correspond to the respective directions of y, z and x axes.
(109) Next, this X plate quartz crystal is, first, rotated with an angle .sub.x of 30 to +30 about the x axis, and second, rotated with an angle .sub.y of 40 to +40 about y axis which is the new axis of the y axis. In this case, the new axis of the x axis changes to x axis and the new axis of the z axis changes to z axis because the z axis is rotated twice about two axes. The length-extensional mode quartz crystal resonator of the present invention is formed from the quartz crystal plate with the rotation angles.
(110) In other words, according to an expression of IEEE notation, a cutting angle of the resonator of the present invention can be expressed by XYtl(30 to +30)/(40 to +40). By choosing a cutting angle of the resonator, a turn over temperature point T.sub.p can be taken at an arbitrary temperature. In this embodiment, length L.sub.0, width W.sub.0 and thickness T.sub.0 correspond to y, z and x axes, respectively. But, when the X plate is rotated once about the x axis, the z axis corresponds to the z axis. In addition, the vibrational portion 63 has a dimension of length L.sub.0 greater than width W.sub.0 and thickness T.sub.0 smaller than the width W.sub.0. Namely, a coupling between length-extensional mode and width-extensional mode gets so small as it can be ignored, as a result of which, the quartz crystal resonator can vibrate in a single length-extensional mode.
(111) In more detail, resonance frequency of the length-extensional mode resonator is inversely proportional to length L.sub.0, and it is almost independent on such an other dimension as width W.sub.0, thickness T.sub.0, connecting portions and supporting portions. Also, in order to obtain a length-extensional mode quartz crystal resonator capable of vibrating in a fundamental mode with a frequency of 1 MHz to 10 MHz, the length L.sub.0 is within a range of about 0.26 mm to about 2.7 mm. In addition, when a length-extensional mode resonator vibrates in an overtone mode, an odd number (n) pair of electrodes are disposed on a vibrational portion of the resonator, where n has a value of 1, 3, 5, . . . . In this case, the length L.sub.0 is within a range of about (0.26 to 2.7)n mm. Thus, the miniature length-extensional mode resonator can be provided with the frequency of 1 MHz to 10 MHz. In addition,
(112) Next, a value of a piezoelectric constant e.sub.12 (=e.sub.12) is described, which is of great importance and necessary to excite a flexural mode, quartz crystal resonator and a length-extensional mode quartz crystal resonator of the present invention. The larger a value of the piezoelectric constant e.sub.12 becomes, the higher electromechanical transformation efficiency becomes. The piezoelectric constant e.sub.12 of the present invention can be calculated using the piezoelectric constants e.sub.11=0.171 C/m.sup.2 and e.sub.14=0.0406 C/m.sup.2 of quartz crystal. As a result, the piezoelectric constant e.sub.12 of the present invention is within a range of 0.095 C/m.sup.2 to 0.19 C/m.sup.2 approximately in an absolute value. It is, therefore, easily understood that this value is enough large to obtain a flexural mode, quartz crystal tuning fork resonator and a length-extensional mode quartz crystal resonator with a small series resistance R.sub.1 and a high quality factor Q. Especially, in order to obtain a flexural mode, quartz crystal tuning fork resonator with a smaller series resistance R.sub.1, the e.sub.12 is within a range of 0.12 C/m.sup.2 to 0.19 C/m.sup.2 in the absolute value, and also, a groove and electrodes are provided on at least one of an obverse face and a reverse face of tuning fork tines so that when each tuning fork tine is divided into two portions (an inner portion located at a fork side and an outer portion located opposite to the fork side) versus a central line portion thereof, a value of e.sub.12 of each portion of each tuning fork tine has an opposite sign each other. Namely, when the one of the two portions has e.sub.12 of a plus sign, the other of the two portions has e.sub.12 of a minus sign. In more detail, a groove and electrodes are provided at tuning fork tines so that a sign of e.sub.12 of inner portions of each tuning fork tine is opposite to the sign of e.sub.12 of outer portions of each tuning fork tine.
(113) When an alternating current voltage is applied between the electrodes 64 and 65 shown in
(114)
(115) In addition, a member of the case and the lid is ceramics or glass and a metal or glass, respectively, and a connecting member is a metal or glass with low melting point. Also, a relationship of the resonator, the case and the lid described in this embodiment is applied to a quartz crystal oscillator of the present invention which will be described in
(116)
(117) In addition, in this embodiment, the resonator 90 is mounted at a mounting portion 94 of the case 91 by conductive adhesives 96 or solder. As described above, the amplifier 98 is housed in the quartz crystal unit and mounted at the case 91. Also, the case 91 and the lid 92 are connected through a connecting member 93. For example, the contour mode resonator 90 of this embodiment is the same as one of the flexural mode, quartz crystal tuning fork resonators 10 and 45 described in detail in
(118) Likewise, in this embodiment, a piece of flexural mode, quartz crystal tuning fork resonator is housed in the unit, but the present invention also includes a quartz crystal unit having a plurality of flexural mode, quartz crystal tuning fork resonators, each of which has tuning fork tines and a tuning fork base, and at least two of the plurality of resonators are connected electrically in parallel. In addition, the at least two resonators may be an individual resonator or may be individual resonators that are formed integrally at each tuning fork base through a connecting portion. For example, the at least two resonators comprises two individual resonators, and the two individual resonators are formed so that one of the two individual resonators has a groove in at least one of upper and lower faces of the tuning fork tines, and the other has no groove in at least one of upper and lower faces of the tuning fork tines to get a different turn over temperature point each other. In addition, a shape and a dimension of the groove and the tuning fork tines may be changed to get the different turn over temperature point each other.
(119) Next, a method for manufacturing a quartz crystal oscillator, which constructs an electronic apparatus of the present invention, is described in detail, according to the manufacturing steps.
(120)
(121) Similar to the steps of S-2 and S-3, a metal film and a resist are spread again on the tuning fork shape of S-4 and grooves 146, 147, 148 and 149 each of which has two stepped portions including a first stepped portion and a second stepped portion opposite the first stepped portion in the width direction along the length direction of the tuning fork tines, are formed at the tuning fork tines 143, 144 by the photo-lithographic process and the etching process, namely, in a second etching process different from the first etching process so that the oscillation frequency of the quartz crystal resonator of the tuning fork shape having the grooves which is a second (or first) oscillation frequency, is in the range of 32.78 kHz to 34.9 kHz, preferably, 32.78 kHz to 34.4 kHz, more preferably, 32.78 kHz to 33.85 kHz and a turn over temperature point (turning point) of the quartz crystal resonator thereof is in the range of 15 C. to 35 C., preferably, 18 C. to 30 C. to get a small frequency deviation in the vicinity of room temperature because the quartz crystal resonator of the tuning fork shape has a parabolic curve in frequency temperature behaviour, and the shape of S-5 is obtained after all of the resist and the metal film are removed. In order to obtain the small motional inductance L.sub.1 of the fundamental mode vibration, it is needless to say that the grooves 146, 147, 148 and 149 have the depth t.sub.1 and the depth t.sub.2 larger than 0.021 mm, preferably, larger than 0.025 mm and less than 0.075 mm, more preferably, larger than 0.03 mm and less than 0.055 mm as above-described. In addition, a metal film and a resist are spread again on the shape of S-5 and electrodes which are of opposite electrical polarity, are disposed on sides of the tines and inside the grooves thereof, as be shown in S-6.
(122) Namely, electrodes 150, 153 disposed on the sides of the tuning fork tine 143 and electrodes 155, 156 disposed inside the grooves 148, 149 of the tuning fork tine 144 have the same electrical polarity. Similarly, electrodes 151, 152 disposed inside the grooves 146, 147 of the tuning fork tine 143 and electrodes 154, 157 disposed on the sides of the tuning fork tine 144 have the same electrical polarity. Two electrode terminals are, therefore, constructed. In more detail, when an alternating current (AC) voltage is applied between the terminals, the tuning fork tines vibrate in a flexural mode of an inverse phase because said electrodes disposed on the stepped portions of the grooves and the electrodes disposed opposite to the said electrodes have opposite electrical polarity. In the step of S-6, a piece of quartz crystal tuning fork resonator, capable of vibrating in a flexural mode is shown in the quartz crystal wafer, but a number of quartz crystal tuning fork resonators are actually formed in the quartz crystal wafer. When the grooves are formed at the tuning fork tines, the oscillation frequency of the resonator of the tuning fork shape becomes lower than that of the resonator with no groove, and the quantity of a change of the oscillation frequency is dependent on a number of the grooves, a groove width, a groove length and a groove depth. In this embodiment, the oscillation frequency of the resonator of the tuning fork shape is adjusted in the quartz crystal wafer by forming a metal film on each of at least two of the upper and lower faces of each of the tuning fork tines so that the oscillation frequency which is a third (or second) oscillation frequency is lower than 32.73 kHz, preferably, less than 32.69 kHz, more preferably, greater than 31.6 kHz and less than 32.69 kHz and the metal film is formed after or before the step of S-6, namely, after or before the two electrode terminals are formed to drive the resonator of the tuning fork shape. In more detail, the metal film on each of at least two of the upper and lower faces of each of the tuning fork tines to adjust the oscillation frequency is formed after the tuning fork shape is formed (after the step of S-4) and before the grooves are formed (before the step of S-5) or is formed after the grooves are formed (after the step of S-5) and before the electrodes are disposed (before the step of S-6) or is formed after the electrodes are disposed (after the step of S-6) and before the resonator of the tuning fork shape is mounted on a mounting portion of a case (before the step of S-7 or S-8). Also, when the resonator of the tuning fork shape housed in a unit having a case and a lid has no groove at the tuning fork tines, an oscillation frequency of the resonator of the tuning fork shape formed in a quartz wafer by etching is in the range of 32.78 kHz to 34.9 kHz, preferably, 32.78 kHz to 34.4 kHz, more preferably, 32.78 kHz to 33.85 kHz. In addition, a metal film on each of at least two of the upper and lower faces of each of the tuning fork tines is formed to adjust the oscillation frequency of the resonator so that the oscillation frequency is lower than 32.73 kHz, preferably, less than 32.69 kHz, more preferably, greater than 31.6 kHz and less than 32.69 kHz, and the metal film is formed after or before the electrodes (two electrode terminals) are formed to drive the resonator of the tuning fork shape. In more detail, the metal film on each of at least two of the upper and lower faces of each of the tuning fork tines is formed after the tuning fork shape is formed and before the electrodes are disposed or is formed after the electrodes are disposed and before the tuning fork shape is mounted on a mounting portion of a case. According to the present invention, the metal film on each of at least two of the upper and lower faces of each of the tuning fork tines may be formed before the tuning fork shape is formed.
(123) In addition, the oscillation frequency of the resonator of the tuning fork shape is adjusted to get a fourth (or third) oscillation frequency and a fifth (or fourth) oscillation frequency by separate steps of at least twice and a first adjustment of the oscillation frequency of the resonator is performed in the quartz crystal wafer to get the fourth (or third) oscillation frequency by a laser method or an evaporation method or an ion etching method so that a frequency deviation of the resonator is within a range of 9000 PPM to +5000 PPM (Parts Per Million), preferably, within a range of 9000 PPM to +100 PPM, more preferably, within a range of 2300 PPM to +100 PPM to a nominal frequency of 10 kHz to 200 kHz, e.g. 32.768 kHz. The first adjustment of the oscillation frequency by the laser method or the ion etching method is performed by trimming mass (e.g. the metal films) disposed on tuning fork tines and the first adjustment of the oscillation frequency by the evaporation method is performed by adding mass (e.g. a metal) on tuning fork tines. Namely, those methods can change the oscillation frequency of said resonator. Also, the resonators formed in the quartz crystal wafer are inspected therein and when there is a failure (damaged) resonator, it is removed from the wafer or something is marked on it or it is remembered by a computer.
(124) In this embodiment, the tuning fork shape is formed from the step of S-3 and after that, the grooves are formed at the tuning fork tines, namely, the tuning fork tines are formed before the grooves are formed, but this invention is not limited to said embodiment, for example, the grooves are first formed from the step of S-3 and after that, the tuning fork shape may be formed, namely, the grooves are formed before the tuning fork tines are formed. Also, the tuning fork shape and the grooves may be formed simultaneously, namely, the tuning fork tines and the grooves are formed simultaneously. When the tuning fork tines and the grooves are formed simultaneously, for example, a portion between the tuning fork tines is first etched so that the portion has a groove and a thickness of the portion is less than seven tenths, preferably, one half of a thickness of the quartz crystal wafer to get a required oscillation frequency and a required turn over temperature point, and after that, both of the portion and the groove are formed simultaneously by etching the quartz crystal wafer. For example, when the thickness of the quartz crystal wafer is in the range of 0.07 mm to 0.12 mm, the thickness of the base portion is less than 0.05 mm, preferably, 0.035 mm, more preferably, 0.005 mm. Namely, the portion has the groove as deep as possible to get the required oscillation frequency and the required turn over temperature point. Moreover, when the tuning fork base has cut portions, the portion between the tuning fork tines and the cut portions are formed simultaneously. In addition, when the tuning fork base has a frame portion, the tuning fork shape and the frame portion are formed simultaneously. According to the present invention, when the tuning fork base has at least one of cut portions and a frame portion, the at least one is formed simultaneously with the tuning fork shape. Moreover, for example, when a groove having a plurality of stepped portions is formed in each of upper and lower faces of the tuning fork tines, the groove may be formed simultaneously with at least one of the cut portions and the frame portion. In addition, at least one of the cut portions may be formed in a step different from at least one of the steps of forming the tuning fork tines and forming the grooves at the tuning fork tines. Namely, the at least one of the cut portions is formed before or after at least one of the tuning fork tines and the grooves is formed. Similar to this, the frame portion may be formed in a step different from at least one of the steps of forming the tuning fork tines and forming the grooves at the tuning fork tines. Namely, the frame portion is formed before or after at least one of the tuning fork tines and the grooves is formed. In addition, at least one of the metal films on the upper and lower faces of each of the tuning fork tines to adjust the oscillation frequency of the resonator of the tuning fork shape may be formed before the step of forming the tuning fork tines. Also, the grooves are formed before the tuning fork tines are formed and after that, when the tuning fork tines are formed, the quartz crystal resonator of the tuning fork shape has an oscillation frequency in the range of 32.78 kHz to 34.9 kHz, preferably, 32.78 kHz to 34.4 kHz, more preferably, 32.78 kHz to 33.85 kHz and a turn over temperature point (turning point) of the quartz crystal resonator thereof is in the range of 15 C. to 35 C., preferably, 18 C. to 30 C. In addition, when the tuning fork tines and the grooves are formed simultaneously, the quartz crystal resonator of the tuning fork shape has an oscillation frequency in the range of 32.78 kHz to 34.9 kHz, preferably, 32.78 kHz to 34.4 kHz, more preferably, 32.78 kHz to 33.85 kHz and a turn over temperature point (turning point) of the quartz crystal resonator thereof is in the range of 15 C. to 35 C., preferably, 18 C. to 30 C.
(125) There are two methods of A and B in the following step, as be shown by arrow signs. For the step of A, the tuning fork base 145 of the formed flexural mode, quartz crystal tuning fork resonator 160 is first mounted on a mounting portion 159 of a case 158 by conductive adhesives 161 or solder, as be shown in S-7. Next, a second adjustment of the oscillation frequency for the resonator 160 is performed to get the fifth (or fourth) oscillation frequency by a laser method 162 or an evaporation method or an ion etching method in S-8 so that a frequency deviation is within a range of 100 PPM to +100 PPM to the nominal frequency of 10 kHz to 200 kHz, e.g. 32.768 kHz. Finally, the case 158 and a lid 163 are connected via glass 164 with the low melting point or a metal in S-9. In this case, the connection of the case and the lid is performed in vacuum because the case 158 has no hole to close it in vacuum.
(126) In addition, though it is not visible in
(127) For the step of B, the tuning fork base 145 of the formed resonator 160 is first mounted on a mounting portion 159 of a case 165 by conductive adhesives 161 or solder in S-10, in addition, in S-11 the case 165 and a lid 163 are connected by the same way as that of S-9, in more detail, after the resonator is mounted on the mounting portion of the case or after the resonator is mounted at the mounting portion, and the case and the lid are connected, the second adjustment of the oscillation frequency of the resonator is performed to get the fifth (or fourth) oscillation frequency so that a frequency deviation is generally within a range of 100 PPM to +100 PPM to a nominal frequency of 10 kHz to 200 kHz, e.g. 32.768 kHz in vacuum, but, it may be within a wider range, for example, 950 PPM to +950 PPM when the third adjustment of the oscillation frequency as will be shown as follows, is performed. Finally, a hole 167 constructed at the case 165 is closed in vacuum using such a metal 166 as solder or glass with the low melting point in S-12.
(128) Also, similar to the step of A, the third adjustment of the oscillation frequency may be performed by the laser method after the step of S-12 to get a small frequency deviation to the nominal frequency. As a result of which it is possible to get the resonator with the frequency deviation which is within a range of 50 PPM to +50 PPM to the nominal frequency, e.g. 32.768 kHz. Thus, the frequency deviation of each of the resonators in the case of the steps of A and B is finally within a range of 100 PPM to +100 PPM at most. Also, the second adjustment of the oscillation frequency may be performed after the case and the lid are connected and the hole is closed in vacuum. In addition, the hole is constructed at the case, but may be constructed at the lid. Also, the adjustment of the oscillation frequency of the present invention is performed in vacuum or inert gas such as nitrogen gas or atmosphere, and the values described above are values in vacuum. Furthermore, the oscillation frequency of the quartz crystal resonator of the tuning fork shape comprises the first, second, third, fourth and fifth (or the first, second, third and fourth) oscillation frequencies different each other.
(129) Therefore, the flexural mode, quartz crystal tuning fork resonators and the quartz crystal units manufactured by the above-described method are miniaturized and realized with a small series resistance R.sub.1, a high quality factor Q.sub.1 and low price.
(130) Moreover, in the above-described embodiment, though the first frequency adjustment of the resonators is performed in the quartz crystal wafer and at the same time, when there is a failure resonator, something is marked on it or it is removed from the quartz crystal wafer, but the present invention is not limited to this, namely, the present invention may include the step to inspect the flexural mode, quartz crystal tuning fork resonators formed in the quartz crystal wafer therein, in other words, the step to inspect whether there is a failure resonator or not in the quartz crystal wafer. When there is a failure resonator in the wafer, something is marked on it or it is removed from the wafer or it is remembered by a computer. By including the step, it can increase the yield because it is possible to find out the failure resonator in an early step and the failure resonator does not go to the next step. As a result of which low priced flexural mode, quartz crystal tuning fork resonators can be provided with excellent electrical characteristics.
(131) In this embodiment, the frequency adjustment is performed three times in separate steps, but may be performed at least twice in separate steps. For example, the third adjustment of the oscillation frequency may be omitted. In addition, in order to construct a quartz crystal oscillator, two electrode terminals of the resonators are connected electrically to an amplifier, capacitors and resistors. In other words, a quartz crystal oscillating circuit is constructed and connected electrically so that an amplification circuit comprises a CMOS inverter and a feedback resistor and a feedback circuit comprises a flexural mode, quartz crystal tuning fork resonator, a drain resistor, a capacitor of a gate side and a capacitor of a drain side. Also, the third adjustment of the oscillation frequency may be performed after the quartz crystal oscillating circuit is constructed in a quartz crystal unit.
(132) Likewise, the flexural mode quartz crystal resonator of the tuning fork type has two tuning fork tines in the present embodiments, but embodiments of the present invention include tuning fork tines more than two. In addition, the quartz crystal tuning fork resonators of the present embodiments are housed in a package (unit) of a surface mounting type comprising a case and a lid, but may be housed in a package of a tubular type.
(133) In addition, for the tuning fork resonators constructing the quartz crystal oscillators of the first embodiment to the fourth embodiment of the present invention, the resonators are provided so that a capacitance ratio r.sub.1 of a fundamental mode vibration gets smaller than a capacitance ratio r.sub.2 of a second overtone mode vibration, in order to obtain a frequency change of the fundamental mode vibration larger than that of the second overtone mode vibration, versus the same change of a value of load capacitance C.sub.L. Namely, a variable range of a frequency of the fundamental mode vibration gets wider than that of the second overtone mode vibration.
(134) In more detail, for example, when C.sub.L=18 pF and the C.sub.L changes in 1 pF, the frequency change of the fundamental mode vibration becomes larger than that of the second overtone mode vibration because the capacitance ratio r.sub.1 is smaller than the capacitance ratio r.sub.2. Therefore, there is a remarkable effect for the fundamental mode vibration, such that the resonators can be provided with the frequency variable in the wide range, even when the value of load capacitance C.sub.L changes slightly. Accordingly, when a variation of the same frequency is required, the number of capacitors which are used in the quartz crystal oscillators decreases because the frequency change versus load capacitance 1 pF becomes large, as compared with that of the second overtone mode vibration. As a result, the low priced oscillators can be provided.
(135) Moreover, capacitance ratios r.sub.1 and r.sub.2 of a flexural mode, quartz crystal tuning fork resonator are given by r.sub.1=C.sub.0/C.sub.1 and r.sub.2=C.sub.0/C.sub.2, respectively, where C.sub.0 is shunt capacitance in an electrical equivalent circuit of the resonator, and C.sub.1 and C.sub.2 are, respectively, a motional capacitance of a fundamental mode vibration and a second overtone mode vibration in the electrical equivalent circuit of the resonator. Namely, the relationship of r.sub.1 less than r.sub.2 implies that the motional capacitance C.sub.1 of the fundamental mode of vibration is greater than the motional capacitance C.sub.2 of the second overtone mode of vibration. In addition, the flexural mode, quartz crystal tuning fork resonator has a quality factor Q.sub.1 for the fundamental mode vibration and a quality factor Q.sub.2 for the second overtone mode vibration.
(136) In detail, the tuning fork resonator of this embodiment is provided so that the influence on resonance frequency of the fundamental mode vibration by the shunt capacitance becomes smaller than that of the second overtone mode vibration by the shunt capacitance, namely, so that it satisfies a relationship of S.sub.1=r.sub.1/2Q.sub.1.sup.2<S.sub.2=r.sub.2/2Q.sub.2.sup.2, preferably, S.sub.1<S.sub.2/2. As a result, the tuning fork resonator, capable of vibrating in the fundamental mode and having a high stable frequency of oscillation can be provided because the influence on the resonance frequency of the fundamental mode vibration by the shunt capacitance becomes so extremely small as it can be ignored. Also, the present invention replaces r.sub.1/2Q.sub.1.sup.2 with S.sub.1 and r.sub.2/2Q.sub.2.sup.2 with S.sub.2, respectively, and here, S.sub.1 and S.sub.2 are called a stable factor of frequency of the fundamental mode vibration and the second overtone mode vibration.
(137) In addition, when a power source is applied to the quartz crystal oscillating circuit, at least one oscillation which satisfies an amplitude condition and a phase condition of vibration starts in the circuit, and a spent time to get to about ninety percent of the steady amplitude of the vibration is called rise time. Namely, the shorter the rise time becomes, the easier the oscillation becomes. When rise time t.sub.r1 of the fundamental mode vibration and rise time t.sub.r2 of the second overtone mode vibration in the circuit are taken, t.sub.r1 and t.sub.r2 are given by t.sub.r1=kQ.sub.1/(.sub.1(1+|RL.sub.1|/R.sub.1)) and t.sub.r2=kQ.sub.2/(.sub.2(1+|RL.sub.2|/R.sub.2)), respectively, where k is constant and .sub.1 and .sub.2 are an angular frequency for the fundamental mode vibration and the second overtone mode vibration, respectively. In addition, t.sub.r1 and t.sub.r2 can be expressed so that t.sub.r1=kL.sub.1/(|RL.sub.1|R.sub.1) and t.sub.r2=kL.sub.2/(|RL.sub.2|R.sub.2) using the relationships of Q.sub.1/.sub.1=L.sub.1/R.sub.1 and Q.sub.2/.sub.2=L.sub.2/R.sub.2, where L.sub.1 and L.sub.2 show a motional inductance of the fundamental mode vibration and the second overtone mode vibration, respectively, in the electrical equivalent circuit of the resonator. Also, when first rise time T.sub.r1 and second rise time T.sub.r2 are, respectively, defined by T.sub.r1=L.sub.1/(|RL.sub.1|R.sub.1) and Tr.sub.2=L.sub.2/(|RL.sub.2|R.sub.2), t.sub.r1 and t.sub.r2 are, respectively, given by t.sub.r1=kTr.sub.1 and t.sub.r2=kTr.sub.2.
(138) From the above-described relation, it is possible to obtain the rise time t.sub.r1 of the fundamental mode vibration less than the rise time t.sub.r2 of the second overtone mode vibration. As a result, the tuning fork resonator can vibrate in the fundamental mode very easily in the oscillating circuit because the rise time t.sub.r1 of the fundamental mode vibration becomes shorter than the rise time t.sub.r2 of the second overtone mode vibration. Also, it is needless to say that the first rise time Tr.sub.1 is less than the second rise time Tr.sub.2 from the relation of the rise time t.sub.r1 less than the rise time t.sub.r2. As an example, when resonance (oscillation) frequency of a flexural mode, quartz crystal tuning fork resonator is about 32.768 kHz for a fundamental mode vibration and the resonator has a value of W.sub.2/W=0.5, t.sub.1/t=0.34 and l.sub.1/l=0.48, though there is a distribution in production, as an example, the resonator has a value of Q.sub.1=62,000 and Q.sub.2=192,000, respectively. In this embodiment, Q.sub.2 has a value of about three times of Q.sub.1. Accordingly, to obtain the t.sub.r1 less than the t.sub.r2, it is necessary to satisfy a relationship of |RL.sub.1|/R.sub.1>2|RL.sub.2|/R.sub.21 by using a relation of .sub.2=6.sub.1 approximately. Also, according to this invention, the relationship is not limited to the quartz crystal oscillating circuit comprising the resonator in this embodiment, but this invention also includes all quartz crystal oscillating circuits to satisfy the relationship. By constructing the oscillating circuit like this, a quartz crystal oscillator with the flexural mode, quartz crystal tuning fork resonator can be provided with a short rise time. In other words, an output signal of the oscillator has an oscillation frequency of the fundamental mode vibration of the resonator and is outputted through a buffer circuit. Namely, the second overtone mode vibration can be suppressed in the oscillating circuit. In this embodiment, the resonator has also a value of r.sub.1=320 and r.sub.2=10,600 as an example. According to this invention, r.sub.1 has a value of 210 to 520. In addition, the capacitance ratios r.sub.1 and r.sub.2 can be rewritten so that r.sub.1=C.sub.0.sub.1.sup.2L.sub.1 and r.sub.2=C.sub.0.sub.2.sup.2L.sub.2 using the motional inductance L.sub.1 of the fundamental mode vibration and the motional inductance L.sub.2 of the second overtone mode vibration. Therefore, a ratio (L.sub.1/L.sub.2) of the motional inductance L.sub.1 of the fundamental mode vibration and the motional inductance L.sub.2 of the second overtone mode vibration is less than 36 approximately from the relations of r.sub.1 less than r.sub.2 and .sub.2=6.sub.1 approximately. Also, the ratio (L.sub.1/L.sub.2) is less than 6(Q.sub.1/Q.sub.2) from the relation of R.sub.1<R.sub.2, preferably, less than 5.16((Q.sub.1/Q.sub.2) from the relation of R.sub.1<0.86R.sub.2 because R.sub.1 and R.sub.2 are defined by R.sub.1=.sub.1L.sub.1/Q.sub.1 and R.sub.2=.sub.2L.sub.2/Q.sub.2, respectively. In addition, r.sub.2 is greater than 1,500, preferably, 2,000.
(139) The above-described quartz crystal resonators are formed by at least one method of chemical, mechanical and physical methods. The mechanical method, for example, uses a particle such as GC#1000 and the physical method, for example, uses atom or molecule. Therefore, these methods are called a particle method here. In addition, the present invention is not limited to the resonators described above, but includes such a piezoelectric resonator for sensing pressure as a flexural mode, tuning fork resonator, a torsional mode resonator, a thickness shear mode resonator, SAW resonator and so on. In detail, there is a relationship between the pressure and an oscillation frequency of the resonators or a series resistance R.sub.1 thereof. In more detail, the higher the pressure becomes, the lower the oscillation frequency becomes or the higher the series resistance R.sub.1 becomes. Namely, since the oscillation frequency of the resonators or the series resistance thereof changes by a change of the pressure, the pressure is measured from the relationship.
(140) Thus, the electronic apparatus of this invention comprising a display portion and a quartz crystal oscillator at least may operate normally because the quartz crystal oscillator comprises the quartz crystal oscillating circuit with a high frequency stability, namely, a high frequency reliability.
(141) As described above, it will be easily understood that the electronic apparatus comprising the quartz crystal oscillator comprising the quartz crystal oscillating circuit having the flexural mode, quartz crystal tuning fork resonator with novel shapes, the novel electrode construction and excellent electrical characteristics, according to the present invention, may have the outstanding effects. Similar to this, it will be easily understood that the electronic apparatus comprising the quartz crystal oscillator comprising the quartz crystal oscillating circuit having the length-extensional mode quartz crystal resonator with the novel cutting angle and the novel shape, according to the present invention, may have also the outstanding effect. In addition to this, while the present invention has been shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that the changes in shape and electrode construction can be made therein without departing from the spirit and scope of the present invention.