Piezoelectric element having thickness shear vibration and mobile communication device using the same
First Claim
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1. A piezoelectric element comprising:
- a piezoelectric substrate having a shape of an elongated rectangular solid, and first and second exciting electrodes formed on a part of at least one principal plane selected from the group consisting of a first principal plane of the piezoelectric substrate and a second principal plane opposed to the first principal plane, wherein thickness shear vibration occurs, a vibration direction of the thickness shear vibration is nonparallel to a side wall extending in a longitudinal direction of the piezoelectric substrate, and a normal line of an edge in the longitudinal direction of the first exciting electrode and a normal line of an edge in the longitudinal direction of the second exciting electrode are parallel to each other, and are nonparallel to the side wall extending in the longitudinal direction of the piezoelectric substrate.
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Abstract
A piezoelectric element includes a piezoelectric substrate formed of a piezoelectric material and a pair of electrodes formed on a first principal plane and a second principal plane of the piezoelectric substrate, wherein thickness shear vibration occurs, and the vibration direction of the thickness shear vibration is nonparallel to the side walls of the piezoelectric substrate.
30 Citations
15 Claims
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1. A piezoelectric element comprising:
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a piezoelectric substrate having a shape of an elongated rectangular solid, and first and second exciting electrodes formed on a part of at least one principal plane selected from the group consisting of a first principal plane of the piezoelectric substrate and a second principal plane opposed to the first principal plane, wherein thickness shear vibration occurs, a vibration direction of the thickness shear vibration is nonparallel to a side wall extending in a longitudinal direction of the piezoelectric substrate, and a normal line of an edge in the longitudinal direction of the first exciting electrode and a normal line of an edge in the longitudinal direction of the second exciting electrode are parallel to each other, and are nonparallel to the side wall extending in the longitudinal direction of the piezoelectric substrate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
wherein the first and second exciting electrodes are formed along an entire width in a traverse direction of the substrate on said at least one principal plane. -
3. The piezoelectric element according to claim 2,
wherein the piezoelectric substrate is formed of LiTaO3 single crystal, the first exciting electrode is formed on the first principal plane, and the second exciting electrode is formed on the second principal plane. -
4. The piezoelectric element according to claim 3,
wherein the first and second principal planes are X planes of the piezoelectric substrate, and the side wall in the longitudinal direction is parallel to a plane obtained by rotating an XY plane of the piezoelectric substrate for 56° - to 58°
clockwise about an X-axis.
- to 58°
-
5. The piezoelectric element according to claim 4,
wherein the direction of the normal line is a direction obtained by rotating Y-axis of the piezoelectric substrate for 47° - to 56°
clockwise on a YZ plane.
- to 56°
-
6. The piezoelectric element according to claim 5,
wherein the width W and the thickness H of the piezoelectric substrate satisfy the relationship 2.9≦ - W/H≦
3.1 or 3.7≦
W/H≦
3.9.
- W/H≦
-
7. The piezoelectric element according to claim 6,
wherein the piezoelectric substrate includes first and second piezoelectric substrates, and the first piezoelectric substrate and the second piezoelectric substrate are stacked in such a manner that their polarization directions are opposite to each other. -
8. The piezoelectric element according to claim 6,
wherein the side wall in the longitudinal direction is a plane cleaved by laser irradiation. -
9. The piezoelectric element according to claim 2,
wherein the piezoelectric substrate is formed of LiTaO3 single crystal, the pair of electrodes includes an input electrode and an output electrode, the input electrode and the output electrode are formed on the first principal plane of the piezoelectric substrate, the piezoelectric element further comprises a ground electrode formed on the second principal plane, the side wall is a side wall in a longitudinal direction of the piezoelectric substrate, and a normal line of an edge of the input electrode and a normal line of an edge of the output electrode are parallel to each other and are nonparallel to the side wall in the longitudinal direction. -
10. The piezoelectric element according to claim 9,
wherein the first and second principal planes are X planes of the piezoelectric substrate, and the side wall of the piezoelectric substrate is parallel to a plane obtained by rotating an XY plane of the piezoelectric substrate for 56° - to 58°
clockwise about an X-axis.
- to 58°
-
11. The piezoelectric element according to claim 10,
wherein the direction of the normal line is a direction obtained by rotating a Y-axis of the piezoelectric substrate for 47° - to 56°
clockwise on a YZ plane.
- to 56°
-
12. The piezoelectric element according to claim 11,
wherein the width W and the thickness H of the piezoelectric substrate satisfy the relationship 2.9≦ - W/H≦
3.1 or 3.7≦
W/H≦
3.9.
- W/H≦
-
13. The piezoelectric element according to claim 12,
wherein the piezoelectric substrate includes a first piezoelectric substrate and a second piezoelectric substrate, and the first piezoelectric substrate and the second piezoelectric substrate are stacked in such a manner that their polarization directions are opposite to each other. -
14. The piezoelectric element according to claim 12,
wherein the side wall in the longitudinal direction is a plane cleaved by laser irradiation. -
15. A mobile communication device comprising the piezoelectric element according to claim 1.
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