Piezoelectric element and piezoelectric device using the same

Patent metadata

Field	Value
Publication number	US-9406861-B2
Application number	US-201313969759-A
Country	US
Kind code	B2
Filing date	Aug 19, 2013
Priority date	Mar 1, 2011
Publication date	Aug 2, 2016
Grant date	Aug 2, 2016

Abstract

A piezoelectric element, which is capable of being driven with a relatively low voltage and obtaining a large displacement amount at a central portion thereof and is not degraded in characteristics over time and is easily mountable on or in a piezoelectric device, includes a piezoelectric body including a plurality of laminated piezoelectric layers, ground electrodes, central electrodes, and peripheral electrodes. A surface of the piezoelectric body includes first to fifth terminals. The extraction of the ground terminals, the central electrodes, and the peripheral electrodes to the first to fifth terminals is configured to connect one terminal of an alternating-current power supply to the third terminal and connect the other terminal of the alternating-current power supply to the first terminal and the second terminal.

First claim

What is claimed is:

1. A piezoelectric element comprising:
a piezoelectric body including a plurality of laminated piezoelectric layers;
a plurality of ground electrodes provided between every other one of the plurality of piezoelectric layers;
a plurality of central electrodes provided between at least two of the plurality of piezoelectric layers not provided with the ground electrodes, and located in respective central portions of the at least two of the plurality of piezoelectric layers; and
a plurality of peripheral electrodes provided between the at least two of the plurality of piezoelectric layers provided with the central electrodes, and surrounding the central electrodes; wherein
the piezoelectric body includes a surface provided with a first terminal, a second terminal, a third terminal, a fourth terminal, and a fifth terminal sequentially arranged in a line;
the plurality of ground electrodes are extracted to the third terminal; and
when the piezoelectric body is divided into a first portion and a second portion at an interlayer plane located at a center or an approximate center in a lamination direction of the plurality of piezoelectric layers, the central electrodes provided in the first portion and the peripheral electrodes provided in the second portion are extracted to the first terminal and the fourth terminal, and the peripheral electrodes provided in the first portion and the central electrodes provided in the second portion are extracted to the second terminal and the fifth terminal, or the central electrodes provided in the first portion and the peripheral electrodes provided in the second portion are extracted to the second terminal and the fifth terminal, and the peripheral electrodes provided in the first portion and the central electrodes provided in the second portion are extracted to the first terminal and the fourth terminal.

2. The piezoelectric element according to claim 1 , wherein at least two of the plurality of piezoelectric layers sandwiched by the ground electrodes, and the central electrodes and the peripheral electrodes are each polarized in opposite directions between a central portion and a peripheral portion thereof.

3. The piezoelectric element according to claim 1 , wherein electrical connection between the plurality of piezoelectric layers is provided by vias defined by pierced holes in the plurality of piezoelectric layers that are filled with a conductive material.

4. The piezoelectric element according to claim 3 , wherein, for electrical connection by the vias between piezoelectric layers separated from each other by two or more of the plurality of piezoelectric layers interposed therebetween, the vias provided in adjacent ones of the plurality of piezoelectric layers are arranged to be alternately shifted with respect to one another when viewed in the lamination direction of the piezoelectric layers.

5. The piezoelectric element according to claim 3 , wherein, for electrical connection by the vias between non-adjacent layers of the plurality of piezoelectric layers, a plurality of relay electrodes are provided between layers of the plurality of piezoelectric layers located between the non-adjacent layers, and overlap when viewed in the lamination direction of the piezoelectric layers, and the plurality of relay electrodes are arranged to each have a shape selected from two or more shapes, arranged to have the same or substantially the same shape and be alternately shifted with respect to each other, or arranged to have the same or substantially the same shape and to be rotated with respect to one another.

6. A piezoelectric device comprising:
a piezoelectric device body; and
the piezoelectric element according to claim 2 mounted on or in the piezoelectric device body as a drive source; and
an alternating-current power supply including a first terminal connected to the third terminal of the piezoelectric element and a second terminal connected to both of the first terminal and the second terminal of the piezoelectric element or to both of the fourth terminal and the fifth terminal of the piezoelectric element.

7. The piezoelectric device according to claim 6 , wherein the connection between the first and second terminals of the alternating-current power supply and the first to fifth terminals of the piezoelectric element is provided by metal terminal members, and the filled vias are not arranged in portions of respective surfaces of the first to fifth terminals in contact with the metal terminal members.

8. The piezoelectric device according to claim 6 , wherein the piezoelectric device is a piezoelectric pump.

9. The piezoelectric element according to claim 1 , wherein the plurality of piezoelectric layers are primarily made of PZT.

10. The piezoelectric element according to claim 1 , further comprising a dummy provided on the surface of the piezoelectric body and spaced away from the first to fifth terminals.

11. The piezoelectric element according to claim 1 , wherein the first to fifth terminals are arranged in a line along an edge of the piezoelectric body.

12. The piezoelectric element according to claim 1 , wherein each of the plurality of ground electrodes has a circular or substantially circular shape.

13. The piezoelectric element according to claim 1 , wherein each of the plurality of peripheral electrodes has a ring shape.

14. The piezoelectric element according to claim 1 , wherein each of the plurality of central electrodes has a circular or substantially circular shape.

15. The piezoelectric element according to claim 1 , wherein each of the plurality of ground electrodes includes an extraction electrode connected to the third terminal.

16. The piezoelectric element according to claim 1 , wherein each of the plurality of central electrodes includes an extraction electrode connected to one of the first, second, fourth, or fifth terminal.

17. The piezoelectric element according to claim 1 , wherein each of the plurality of peripheral electrodes includes an extraction electrode connected to one of the first, second, fourth, or fifth terminal.

18. The piezoelectric device according to claim 7 , wherein the metal terminal members are connected to respective ones of the first and second terminals of the alternating-current power supply and the first to fifth terminals of the piezoelectric element by a conductive paste or solder.

19. The piezoelectric device according to claim 7 , wherein each of the metal terminal members is in partial contact with at least one of the first and second terminals of the alternating-current power supply and the first to fifth terminals of the piezoelectric element by a conductive paste or solder.

20. The piezoelectric device according to claim 7 , wherein none of the metal terminal members are in direct contact with any of the first and second terminals of the alternating-current power supply and the first to fifth terminals of the piezoelectric element by a conductive paste or solder.

Assignees

• Murata Manufacturing Co

Inventors

• Ukai Hiroyuki
• Kanai Shungo
• Hayashi Hiroyuki

Classifications

• H01L41/0471

  Electricity · mapped topic

• H01L41/0973

  Electricity · mapped topic

• H01L41/083

  Electricity · mapped topic

• H01L41/0474

  Electricity · mapped topic

• F04B43/046 Primary

  with piezoelectric drive · CPC title