A piezoelectric device includes a conductive adhesive, a container, and an AT-cut crystal element. The AT-cut crystal element has at least one side surface intersecting with a Z′-axis of the crystallographic axis of the crystal constituted of three surfaces. When a dimension of a straight-line portion along the Z′-axis of a second side opposed to the first side is expressed as W1 and a dimension along the Z′-axis of the AT-cut crystal element is expressed as W0, W1/W0 is 0.91 or greater, and the straight-line portion has both sides constituting corner portions in approximately right angles with sides along an X-axis of the crystal of the AT-cut crystal element. The side of the first side is at a −X-side in an X-axis of the crystallographic axis of the crystal and a side of the second side is at a +X-side in the X-axis.

A vibrator includes: a vibration element that includes a pair of first excitation electrodes formed at the first vibration portion, a pair of second excitation electrodes formed at the second vibration portion, and a pair of third excitation electrodes formed at the third vibration portion, in which one second excitation electrode of the pair of second excitation electrodes is formed at a first inclined surface that is inclined with respect to two main surfaces, and one third excitation electrode of the pair of third excitation electrodes is formed at a second inclined surface that is inclined with respect to the two main surfaces and the first inclined surface; and a package that houses the vibration element. The vibration element includes a fixing portion to be fixed to the package. The fixing portion is provided between the first vibration portion and the second and third vibration portions.

A vibrator device includes a first excitation electrode, a first pad electrode, and a first drawn wiring line that are disposed at a first surface of a vibrator element, a second excitation electrode, a second pad electrode, and a second drawn wiring line that are disposed at a second surface of the vibrator element, and a spiral first electrode pattern disposed at the first surface of the vibrator element. The first excitation electrode and the second excitation electrode are disposed so as to face each other with the vibrator element therebetween. A first central end section of the first electrode pattern is electrically coupled to the second drawn wiring line via a through electrode provided in the vibrator element. A first outer circumferential end section of the first electrode pattern is electrically coupled to the first drawn wiring line. The first drawn wiring line is electrically coupled to at least one of the first excitation electrode and the first pad electrode. The second drawn wiring line is electrically coupled to at least one of the second excitation electrode and the second pad electrode.

An oscillator includes dual resonators mounted in a helium filled coldweld holder. One resonator operates at anti-resonance into a load capacitance of about 20 picofarads, and operates on a third overtone frequency under noncontrolled temperature conditions. The other resonator operates on a fundamental mode at anti-resonance in a load capacitance of about 32 picofarads. Resonator crystals in a dual-crystal resonator may include a theta-angle shift to equalize frequency versus temperature curves at temperature extremes.

A bulk acoustic wave (BAW) structure includes a single crystal piezoelectric material layer, a first electrode, a second electrode and an acoustic reflector. The first and second electrodes are respectively located on a first surface and a second surface of the single crystal piezoelectric material layer. The area of the second electrode is greater than or equal to that of the second surface of the single crystal piezoelectric material layer, and the contact area of the single crystal piezoelectric material layer with the second electrode is equal to the area of the second surface of the single crystal piezoelectric material layer. The acoustic reflector is disposed on a surface of the first electrode.

The disclosed technology generally relates to quartz crystal devices and more particularly to quartz crystal devices configured to vibrate in torsional mode. In one aspect, a quartz crystal device configured for temperature sensing comprises a fork-shaped quartz crystal comprising a pair of elongate tines laterally extending from a base region in a horizontal lengthwise direction of the fork-shaped quartz crystal. Each of the tines has formed on one or both of opposing sides thereof a vertically protruding line structure laterally elongated in the horizontal lengthwise direction. The quartz crystal device further comprises a first electrode and a second electrode formed on the one or both of the opposing sides of each of the tines and configured such that, when an electrical bias is applied between the first and second electrodes, the fork-shaped quartz crystal vibrates in a torsional mode in which each of the tines twists about a respective axis extending in the horizontal lengthwise direction.

A vibrator device includes a base; and a vibrator element including a quartz crystal vibrator element attached to the base via a first metal bump, in which the first metal bump is disposed on a straight line inclined within a range of +55° to +65° or −65° to −55° with respect to an X axis of the quartz crystal constituting the quartz crystal vibrator element in plan view seen from a direction in which the base and the quartz crystal vibrator element are arranged.

The disclosed technology generally relates to quartz crystal devices and more particularly to quartz crystal devices configured to vibrate in torsional mode. In one aspect, a quartz crystal device configured for temperature sensing comprises a fork-shaped quartz crystal comprising a pair of elongate tines laterally extending from a base region in a horizontal lengthwise direction of the fork-shaped quartz crystal, wherein each of the tines has formed on one or both of opposing sides thereof a pair of vertically recessed groove structures laterally elongated in the horizontal lengthwise direction, wherein the pair of groove structures are separated in a horizontal widthwise direction by a line structure. The quartz crystal device further comprises a first electrode and a second electrode formed on the one or both of the opposing sides of each of the tines and configured such that, when an electrical bias is applied between the first and second electrodes, the fork-shaped quartz crystal vibrates in a torsional mode in which each of the tines twists about a respective axis extending in the horizontal lengthwise direction.

A piezoelectric device includes a piezoelectric vibrating piece and a container. The piezoelectric vibrating piece has a rectangular planar shape and has a portion of a first side secured to the container. The piezoelectric vibrating piece has a second side opposing the first side and includes a projecting portion that projects outward from the second side in at least one of proximity of both ends of the second side along the second side.

In an acoustic wave device, in a rotated Y-cut crystal substrate to which a rotational angle based on a particular Euler angle is added, a vibration mode located farther in a low phase velocity area than the principal vibration has an electromechanical coupling coefficient K.sup.2 lower than that of the principal vibration, and the primary and secondary temperature coefficients of the principal vibration are approximately zero. The acoustic wave device includes a crystal substrate cut from a quartz crystal boule cut by a rotational angle specified by a right-handed Euler angle (ϕ, θ, Ψ), and at least one comb-shape excitation electrode to excite the crystal substrate to make a plate waves. The crystal substrate is made by cutting the quartz crystal boule such that the rotational angle is within ranges of ϕ=0±2°, θ=17.5° to 19.5°, and Ψ=0±2°.