Nihon Dempa Kogyo Co., Ltd.

Shigetaka Kaga

Kazuhiro Hirota

Yoshiro Teshima

Kazuo Akaike

Mitsuaki Koyama

Shigenori Watanabe

Morio Onoe

Masaaki Nakahara

A piezoelectric vibrating piece includes a piezoelectric substrate and excitation electrodes. The excitation electrode includes a main thickness portion and an inclined portion, the main thickness portion has a constant thickness, the inclined portion is formed on a peripheral area of the main thickness portion, the inclined portion gradually decrease in thickness from a part contacting the main thickness portion toward an outermost periphery of the excitation electrode. The inclined portion has a width as an inclination width in a length of 0.84 times or more and 1.37 times or less of a first flexural wavelength and 2.29 times or more and 3.71 times or less of a second flexural wavelength, the first flexural wavelength is a wavelength of a flexure vibration at a fundamental wave of the thickness-shear vibration, the second flexural wavelength is a wavelength of a flexure vibration at a third harmonic of the thickness-shear vibration.

Piezoelectric vibrating piece and piezoelectric device

A piezoelectric vibrating piece includes a piezoelectric substrate, a first excitation electrode, and a second excitation electrode. The piezoelectric substrate is formed into a flat plate shape and vibrates in a thickness-shear vibration mode. The first excitation electrode is formed on one principal surface of the piezoelectric substrate. The second excitation electrode is formed on another principal surface of the piezoelectric substrate. The first excitation electrode is formed to entirely have an identical thickness. The second excitation electrode has a main thickness portion and an inclined portion. The main thickness portion has a constant thickness. The inclined portion is formed in a peripheral area of the main thickness portion and gradually decreases in thickness from a portion in contact with the main thickness portion to an outermost periphery of the second excitation electrode. The main thickness portion has a thickness larger than the thickness of the first excitation electrode.

A crystal resonator vibrates in a thickness-shear mode. The crystal resonator includes excitation electrodes being disposed on a front surface and a back surface of a crystal element. The excitation electrodes are disposed on the crystal element to have a positional relationship, where a displacement distribution at an edge of the excitation electrode on the front surface is identical to a displacement distribution at an edge of the excitation electrode on the back surface.

Crystal resonator

A piezoelectric vibrating piece includes a vibrating piece body including a vibrator and at least one pair of excitation electrodes formed on a front surface and a back surface of the vibrator. The vibrating piece body is a twice rotated quartz-crystal vibrating piece. The pair of excitation electrodes are arranged in a Z'&#x2033;-axis direction determined by an X&#x2032;&#x2033;-axis and obliquely disposed with respect to the Y&#x2033;-axis direction. The X&#x2032;&#x2033;-axis is rotated by 260&#xb0; to 300&#xb0; counterclockwise about a Y&#x2033;-axis using a +X&#x2033;-axis direction as a reference. The pair of excitation electrodes are formed to have respective semicircle shapes including straight line portions extending in the X&#x2032;&#x2033;-axis direction and to be disposed in a state where the straight line portions overlapping with one another. The straight line portion of the excitation electrode includes an inclined portion that gradually decreases in thickness toward an end portion of the excitation electrode.

A piezoelectric vibrating piece includes a vibrating piece body and at least a pair of excitation electrodes. The vibrating piece body includes a vibrator. The pair of excitation electrodes are formed on respective front surface and back surface of the vibrator. The vibrating piece body is a twice rotated quartz-crystal vibrating piece cut out parallel to an X&#x2033;-Z&#x2033; surface. The X&#x2033;-Z&#x2033; surface is rotated around a Z-axis of a crystallographic axis of a crystal and further rotated around an X'-axis. The pair of excitation electrodes are collocated in a Z&#x2032;&#x2033;-axis direction determined by an X&#x2032;&#x2033;-axis. The X&#x2032;&#x2033;-axis is defined by counterclockwise rotation from a +X&#x2033;-axis direction around a Y&#x2033;-axis by 260&#xb0; to 300&#xb0;. The pair of excitation electrodes are disposed inclined with respect to the Y&#x2033;-axis direction.

A piezoelectric plate in the piezoelectric sensor is obtained from a rotated Y-plate where a rotation angle around the X-axis is set according to a type of the piezoelectric crystalline material, a detection region is located on a surface parallel to an X-Z plane, and a transmitting and a receiving parts are opposite to each other at positions sandwiching the detection region along an X-axis direction of the piezoelectric plate. When a guided wave excited by applying a frequency signal from the transmitting part satisfies &#x3be;h=m&#x3c0;/(2&#x3bb;) (2h: thickness of the piezoelectric plate, &#x3be;: wave number in the X-axis, &#x3bb;: wave number in thickness direction normalized by &#x3be;, m: positive even number), the rotation angle satisfies the displacement of a P wave component of the guided wave becomes the maximum, or the displacement of the SH wave component of the guided wave becomes the maximum.

Piezoelectric sensor

There is provided a temperature compensated piezoelectric oscillator which excels in frequency stability and has a good electronic noise characteristic, and with which a circuit can be structured simply. An auxiliary oscillator unitsharing a crystal substratewith a main oscillator unitoutputting a set frequency fto an outside is used as a temperature detecting unitdetecting a temperature T for obtaining a compensation voltage &#x394;V in a temperature compensated piezoelectric oscillator (TCXO), and electrodesof the main oscillator unitand the auxiliary oscillator unitare provided separately on the crystal substrate. For example, a fundamental wave and an overtone are used or a thickness shear vibration and a contour shear vibration are used in the main oscillator unitand the auxiliary oscillator unit, respectively.

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Saitama, Japan

Shigetaka Kaga