Mechanical oscillating system for a clock and functional element for a clock

Abstract

A mechanical oscillating system for a clock including a balance spring manufactured from a non-metallic, polycrystalline material with a grain size between 10 and 50,000 nm, with a winding area of the balance spring 0.001 mm.sup.2 to 0.3 mm.sup.2, an oscillating body and a shaft for mounting of the oscillating body and the balance spring on the shaft. A spiral spring for a clock being manufactured from a non-metallic material, wherein the non-metallic material is a polycrystalline material with a grain size between 10 and 50,000 nm, and having a linear thermal expansion coefficient smaller than 810.sup.6/K.

Claims

1. A mechanical oscillating system for a clock, comprising: a balance spring, wherein the balance spring is manufactured from a polycrystalline silicon having a grain size between 10 and 50,000 nm, a winding area of the balance spring from 0.001 mm.sup.2 to 0.3 mm.sup.2, and a surface of the balance spring is provided with a layer of silicon oxide so that the balance spring has a linear expansion coefficient smaller than 810.sup.6/K; an oscillating body; and, a shaft for mounting of the oscillating body and the balance spring on the shaft; wherein the polycrystalline silicon comprises elongated grains having a grain width between 10 and 1000 nm and a grain length between 5 and 50 m.

2. The mechanical oscillating system recited in claim 1, wherein the grain size is between 10 and 10,000 nm.

3. The mechanical oscillating system recited in claim 1, wherein the winding area of the balance spring is 0.001 mm.sup.2 to 0.03 mm.sup.2.

4. The mechanical oscillating system recited in claim 1, wherein the winding area of the balance spring is 0.001 mm.sup.2 to 0.01 mm.sup.2.

5. The mechanical oscillating system recited in claim 1, wherein the grain length is between 5 and 50 m.

6. The mechanical oscillating system recited in claim 1, wherein the oscillating body, for temperature compensation, is manufactured from a copper-beryllium alloy.

7. The mechanical oscillating system recited in claim 1, wherein the oscillating body is a wheel- or disk-shaped oscillating body.

8. The mechanical oscillating system recited in claim 1, further comprising a spring retainer block with a clamping gap for holding by clamping of the spiral or balance spring in the area of an outer spring end of the balance spring.

9. A spiral spring for a clock being manufactured from a non-metallic material, wherein the non-metallic material is a polycrystalline silicon having a grain size between 10 and 50,000 nm, a surface of the balance spring is provided with a layer of silicon oxide and having a linear thermal expansion coefficient smaller than 810.sup.6/K, wherein the polycrystalline silicon comprises elongated grains having a grain width between 10 and 1000 nm and a grain length between 2 and 50 m.

10. The spiral spring recited in claim 9, wherein the polycrystalline material has a grain size between 10 and 10,000 nm.

11. The spiral spring recited in claim 9 including a winding area is from 0.001 mm.sup.2 to 0.3 mm.sup.2.

12. The spiral spring recited in claim 9, wherein a winding area is from 0.001 mm.sup.2 to 0.03 mm.sup.2.

13. The spiral spring recited in claim 9, wherein a winding area is from 0.001 mm.sup.2 to 0.01 mm.sup.2.

14. The spiral spring recited in claim 9, wherein the grain length is between 5 and 50 m.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is described in more detail below with reference to the following figures and based on exemplary embodiments in which:

(2) FIG. 1 is a simplified functional depiction showing the essential elements of a mechanical oscillating system of a wristwatch;

(3) FIG. 2 is a top view showing the spiral spring of the oscillating system of FIG. 1;

(4) FIG. 3 is a perspective partial view showing a mechanical oscillating system for clocks, especially wristwatches, according to a further embodiment;

(5) FIG. 4 is a component drawing in top view showing the oscillating and balance wheel of the oscillating system of FIG. 3;

(6) FIG. 5 is a perspective view and top view of a centering element of the balance wheel of the oscillating system of FIG. 3;

(7) FIG. 6 is a component drawing showing a spring retainer or retainer block for the spiral or balance spring of the oscillating system of FIG. 3; and,

(8) FIG. 7 is a simplified depiction showing a cross section through a multi-layer coating of a function element manufactured from silicon.

DETAILED DESCRIPTION OF THE INVENTION

(9) The oscillating system generally designated 1 in the drawing consists of the spiral spring 2 and the oscillating or balance wheel 3. The balance spring 2 is manufactured from silicon, preferably from polycrystalline silicon. The balance spring 2 is manufactured, for example, from a non-metallic crystalline or sintered material with a grain size between 10 and 50,000 nm, preferably between 10-10,000 nm, and the column growth of the grain size has a length, for example, of about 5-50 m and a width of 10-1000 nm. Further, the non-metallic crystalline or sintered material has a linear thermal expansion coefficient smaller than 810.sup.6/K or the balance spring 2 is manufactured using a wafer from this material or from silicon, e.g., by cutting and/or etching (masking and etching technology). The wafer is produced, for example, by epitaxial deposition. The cross-sectional area of the spring winding is, for example, 0.001-0.01 mm.sup.2.

(10) The balance spring 2 is provided on the outer surface of its windings with a layer of silicon oxide which is produced thermally, for example. This layer has a maximum thickness of 4 m, preferably a maximum thickness of 3 m or less.

(11) The oscillating mass or the oscillating body, i.e., the oscillating or balance wheel 3, which, for example, has the shape of a spoked wheel typical of such balance wheels, is manufactured from molybdenum or an alloy with a high molybdenum content. In an example embodiment, the oscillating body is manufactured from a copperberyllium alloy for temperature compensation. Due to the combination of silicon (for the balance spring 2) and molybdenum (for the balance wheel 3), an optimally temperature compensated mechanical oscillating system is obtained, i.e., its accuracy or frequency precision is independent especially of temperature changes, among other factors.

(12) FIG. 2 shows the spiral spring 2 again in a component drawing. A special feature of this spiral spring is that it is designed to be multiply wave-shaped in the area of its outer spring end at 2.1. This area results in an improved, very even oscillating behavior of the spiral spring 2.

(13) The spiral spring 2 with the section 2.1 is advantageously also usable for oscillating systems for clocks, especially wristwatches, in which the oscillating mass is designed otherwise than as described above.

(14) FIG. 3 shows a perspective view of an oscillating system 1a with the spiral spring 2a and the oscillating or balance wheel 3a. The balance spring 2a and the balance wheel 3a are manufactured from the same material and/or in the same manner as described above for the spiral spring 2 and the balance wheel 3.

(15) The balance wheel 3a is designed in the shape of a spoked wheel, comprising an outer ring 4, four spokes 5 extending radially inward from the ring 4 and a middle hub section 6, which includes an opening 6.1 for mounting on the balance staff and is manufactured as one piece with the spokes 5 and the outer ring 4.

(16) The outer ring 4 is provided on its inner side with a circumferential groove 7 and with a fork-like mounting section 8 respectively between the spokes 5. On each mounting section 8 there is an adjusting element 9, which is manufactured as one piece from a non-magnetic metal material, e.g., of molybdenum or of a non-corrosive steel. The adjusting elements 9, which like the spokes 5 are arranged at equal angle distances around the axis of the balance wheel 3a or the opening 6.1, can be used to adjust the dynamic moment of inertia of the balance wheel 3a to define the frequency or oscillation period of the oscillating system. The mounting sections 8 are provided respectively under the groove 7.

(17) For this purpose, the adjusting elements 9 consist of a circular body 10 with a journal 11 which has a cylindrical outer surface and is positioned axially congruent with the axis of said body and extends over one front end of the centering element 9. Further, a curved recess 12 is provided in the body 10, which (recess) is open and curved in an arc-shape on both faces of the disk-shaped body 10 and which extends somewhat less than 180 around the axis of the centering element 9, namely, such that the centering element 9 or its body 10 comprises a continuous edge on its outside circumference, but the center of mass of the centering element 9 is radially offset to the axis of the centering element 9. On the top side facing away from the journal 11, the body 10 is further provided with a slot-shaped recess 13 extending radially or approximately radially to the axis of the centering element and forming the contact or actuating surface for an adjusting tool, for example, for a screwdriver. Each centering element is supported by the journal 11 on one mounting section 8 rotatably around an axis parallel to the axis of the balance wheel 3a, with a certain resistance to rotation due to the fact that the respective journal 11 is held on the fork-shaped mounting section 8 by snapping or locking into place and the outer periphery of the disk shaped body 10 of each adjusting element 9 extends into the groove 7, is axially secured therein and bears radially against the bottom of the groove.

(18) Mounting of the adjusting elements 9 on the ring 4 therefore takes place in the manner that the journal 11 of each adjusting element 9 is pushed radially onto the corresponding fork-shaped mounting section 8. By turning or swiveling the adjusting elements 9 around the axis of the journals 11, the center of mass of each adjusting element can be displaced, e.g., radially to the axis of the balance wheel 3a so that the dynamic mass moment of inertia can be adjusted in the desired manner. After adjusting the adjusting elements 9, they are secured by means of a suitable adhesive or sealing coat.

(19) The balance spring 2a is fastened at its inner end to the balance staff, which is not depicted, in the drawings. The outer end of the spiral spring 2a is held on a spring retainer block 14 of a spring retainer 15 which is adjustable around the axis of the balance wheel 3a.

(20) As can be seen especially in FIG. 6, the spring retainer block 14, which is manufactured from a metal material, is designed with a section 14.1 with which it can be fastened in an opening 16 of the spring retainer 15 by clipping or locking, and with a section 14.2 with two fork or clamping arms 17 and 18, which in between form a clamping gap 19 in which the spiral spring 2a can be fastened by clamping. The clamping gap 19 is open toward the bottom side facing away from the section 14.1 and also toward two opposing faces of the spring retainer block 14 and is limited by a surface 20.1 on the side facing the section 14.1.

(21) In an assembled state, the spring retainer block 14 is oriented with its longitudinal extension parallel to the axis of the balance wheel 3a. During assembly of the oscillating system the outer section of the spiral spring 2a is inserted into the clamping gap 19 from the bottom side of the spring retainer block 14 facing away from the section 14.1 or the spring retainer 15. Therefore, the spiral spring 2a is already held on the spring retainer block 14 mounted on the spring retainer 15 so that an alteration and adjustment of the effective spring length required for adjusting the frequency of the mechanical oscillating system is possible by moving the spiral spring 2a relative to the spring retainer block 14 while maintaining the clamping connection. After this adjustment, the connection between the spiral spring 2a and the spring retainer block 14 is secured using a suitable adhesive or sealing coat.

(22) The adjusting elements 9, and, in particular, the respective spring retainer block 14, are preferably manufactured as so-called LIGA parts using the LIGA process known to persons skilled in the art, and through which the process steps of lithography, electroplating and molding enables the manufacture of metal pre-formed bodies with very small dimensions.

(23) FIG. 7 schematically shows the embodiment of a bearing and/or sliding and/or mounting surface of a functional element 21, which is made of silicon, preferably of polycrystalline silicon, for example, epitaxially deposited polycrystalline silicon. The surface 22 forming the bearing and/or sliding and/or mounting surface of the functional element 21 is formed by a multi-layer coating, at least comprising a coating 23 of silicon oxide which adjoins directly to the silicon material of the functional element 21 and is produced, for example, by thermal oxidation or another suitable manner. The coating 23 is followed by a metal intermediate layer 24 which preferably consists of titanium-nitride and/or titanium carbide and/or tungsten carbide and is applied, for example, in a physical vapor deposition (PVD) coating process. The intermediate layer 24 can in turn be multi-layered, namely, with several single layers, e.g., of the above-named materials. The intermediate layer 24 is followed by the coating 25 forming the actual outer surface which is embodied as a DLC or diamond like carbon coating and is produced, for example, through chemical vapor deposition (CVD). The invention is based on the finding that the metal intermediate layer 24 achieves improved adhesion of the layer 25 to the layer 23, so that chipping or flaking of the layer 25 from the functional element 21 is effectively prevented during assembly and during use of a clock. This applies not only to bearing and sliding surfaces, but also in particular to mounting surfaces and especially also to such surfaces with which or on which fastening by clamping is used, for example, fastening by clamping of the spiral or balance spring or of the oscillating body to a shaft, etc.

(24) The invention is described above based on exemplary embodiments. It goes without saying that numerous modifications and variations are possible without abandoning the underlying inventive idea upon which the invention is based. Instead of the above-mentioned silicon material (e.g., polycrystalline silicon), particularly suitable is also a silicon-based sintered material or silicon-sintered material and/or a non-metal crystalline or sintered material with a grain size between 10 and 50,000 nm and a linear thermal expansion coefficient smaller than 810.sup.6/K.

REFERENCE NUMBERS

(25) 1, 1a Mechanical oscillating system 2, 2a Balance spring 3, 3a Balance wheel 4 Band or ring 5 Spoke 6 Hub-shaped section 7 Groove 8 Fastening section 9 Adjusting element 10 Disk-shaped body of adjusting element 9 11 Journal of adjusting element 9 12 Recess 13 Slot 14 Spring retainer block 14.1, 14.2 Section of spring retainer block 15 Spring retainer 16 Opening 17, 18 Clamping arm 19 Clamping gap 20 Contact surface 21 Function element 22 Surface of function element 21 23, 24, 25 Coating or layer