Nihon Dempa Kogyo Co., Ltd.

Ndk Saw Devices Co., Ltd.

Kazuhiro Hirota

Yoshiro Teshima

Shigetaka Kaga

Tetsuya Watanabe

Hirokazu Iwata

Yuya Hiratsuka

Atsushi Mori

Yoshiharu Sato

Masaaki Nakahara

Takahiro Ohtsuka

Shinobu Yoshida

Kazuhiko Osawa

Koji Toshikawa

Osamu Tokuda

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 Wand a dimension along the Z′-axis of the AT-cut crystal element is expressed as W, W/Wis 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.

Piezoelectric device and manufacturing method of the same

A surface acoustic wave device includes a quartz layer, a piezoelectric layer, and an Inter Digital Transducer. A rotation in a right-screw direction is assumed as a +-rotation. A three-dimensional coordinate system formed by an x1-axis, a y1-axis, and a z1-axis respectively matching an X-axis, a Y-axis, and a Z-axis as crystallographic axes of a quartz-crystal is rotated from +125.25&#xb0; in a range of &#xb1;3&#xb0; with the x1-axis as a rotation axis. Subsequently, the three-dimensional coordinate system is rotated from +45&#xb0; in a range of &#xb1;2&#xb0; with the z1-axis as the rotation axis. Subsequently, the three-dimensional coordinate system is rotated from &#x2212;45&#xb0; in a range of &#xb1;2&#xb0; with the x1-axis as the rotation axis. The quartz layer is cut along a surface as a sectional plane perpendicular to the z1-axis. The quartz layer has a propagation direction of the surface acoustic wave in a direction parallel to the x1-axis.

Surface acoustic wave device

A surface acoustic wave device includes a quartz layer, an amorphous silicon oxide layer, a piezoelectric layer, and an Inter Digital Transducer. The amorphous silicon oxide layer is laminated on the quartz layer. The piezoelectric layer is laminated on the amorphous silicon oxide layer. The Inter Digital Transducer is formed on the piezoelectric layer. The Inter Digital Transducer excites a surface acoustic wave on the piezoelectric layer. Assuming that the surface acoustic wave has a wavelength &#x3bb;,

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 crystal unit includes an AT-cut crystal element that has a planar shape in a rectangular shape and a part as a thick portion. The crystal element includes a first end portion, a depressed portion, the thick portion, and a second end portion in this order from a side of one short side in viewing a cross section taken along a longitudinal direction near a center of the short side. The depressed portion is a depressed portion disposed from the thick portion toward the first end portion side, depressed with a predetermined angle &#x3b8;a and subsequently bulged, and connected to the first end portion.

Crystal unit and manufacturing method thereof

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.

An AT-cut crystal element includes a crystal element having two side surfaces (namely, a Z'-surface) intersecting with a Z-axis of a crystallographic axis thereof. At least one of the two side surfaces is constituted of three of first to third surfaces. The first to the third surfaces meeting following conditions: the first to the third surfaces intersect with one another in this order and formed by rotating a principal surface of the crystal element by predetermined angles; and expressing the angle of the first surface as &#x3b8;, a length of the first surface as D, a thickness of a part of the crystal element having the principal surface as t, and M=D/t, and a conversion percentage as fn (M, (&#x3b8;)), the &#x3b8;and the M are set such that the conversion percentage fn (M, (&#x3b8;)) becomes a predetermined value Th or less.

AT-cut crystal element, crystal resonator and crystal unit

A surface acoustic wave device includes a quartz substrate and a periodic structure portion. The quartz substrate is constituted such that a surface acoustic wave is to propagate on a surface with an Euler angle of (0&#xb0;, 16&#xb0;&#x3c;&#x3b8;&#x2266;18.5&#xb0;, 0&#xb0;). The periodic structure portion is disposed on the quartz substrate and includes a plurality of electrodes extending in a direction intersecting with a direction of the propagation of the surface acoustic wave. The electrodes are disposed in parallel to one another along the propagation direction. The periodic structure portion is constituted to mainly contain aluminum. When a width dimension of the electrode in the propagation direction and a separation dimension between the electrodes adjacent to one another are respectively defined as L and S, a metallization ratio &#x3b7; (&#x3b7;=L&#xf7;(L+S)) is set to 0.4 or less.

Surface acoustic wave device and oscillator circuit

Disclosed is a surface acoustic wave device which has IDT electrodes arranged over a lithium tantalate piezoelectric substrate and is capable of suppressing propagation losses even at a high frequency band equal to or higher than 2 GHz as low as possible in order to utilize surface acoustic waves including LSAW. For this purpose, 45&#xb0; to 46&#xb0; rotated YX-cut lithium tantalate substrate is used as the piezoelectric substrate, a thickness of the IDT electrode is set to 7.5% &#x3bb; to 8% &#x3bb;, and a metallization ratio in electrode fingers of the IDT electrode is set to 0.55 to 0.65.

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Saitama, Japan

Kazuhiro Hirota