PIEZOELECTRIC VIBRATOR

• US 20160005951A1
• Filed: 01/23/2014
• Published: 01/07/2016
• Est. Priority Date: 01/31/2013
• Status: Active Grant

• Current Assignee: A School Corporation Kansai University, Murata Manufacturing Co Limited
• Original Assignee: A School Corporation Kansai University, Teijin Limited
• Inventors: YOSHIDA, Tetsuo, TAJITSU, Yoshiro, KATO, Atsuko
• Granted Patent: US 9,929,335 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04R 17/005 using a piezoelectric polymer
• CPC Class Codes: H04R 7/04 Plane diaphragms
• CPC Class Codes: H10N 30/057 by stacking bulk piezoelectric or electrostrictive bodies and electrodes
• CPC Class Codes: H10N 30/20 with electrical input and mechanical output, e.g. functioning as actuators or vibrators
• CPC Class Codes: H10N 30/50 having a stacked or multilayer structure
• CPC Class Codes: H10N 30/857 Macromolecular compositions
• CPC Class Codes: H10N 30/871 Single-layered electrodes of multilayer piezoelectric or electrostrictive devices, e.g. internal electrodes
• CPC Class Codes: H10N 30/886 Additional mechanical prestressing means, e.g. springs

Abstract

The invention relates to a piezoelectric vibrator having a piezoelectric laminate in which oriented film layers made of a polylactic acid and conductive layers are laminated alternately and grippers gripping both ends of the piezoelectric laminate, wherein one of two conductive layers neighboring via an oriented film layer is short-circuited to a negative electrode and the other conductive layer is short-circuited to a positive electrode, the oriented film layers interposed between the respective conductive layers are laminated such that the oriented film layers expand and contract in the same direction when a current is applied, the piezoelectric laminate has two parallel surfaces which are parallel to the plane direction of the oriented film layers and two end faces A and B which are between the parallel surfaces and parallel to each other, and the gripped ends respectively include the end face A and the end face B.

Claims

1. A piezoelectric vibrator having a piezoelectric laminate in which oriented film layers made of a polylactic acid and conductive layers are laminated alternately and grippers gripping both ends of the piezoelectric laminate:

wherein

(i) the piezoelectric laminate is laminated in such a manner that one of two conductive layers neighboring via an oriented film layer is short-circuited to a negative electrode and the other conductive layer is short-circuited to a positive electrode and the oriented film layers interposed between the respective conductive layers expand and contract in the same direction when a current is applied;

(ii) the piezoelectric laminate has two parallel surfaces which are parallel to the plane direction of the oriented film layers and two end faces A and B which are between the parallel surfaces and parallel to each other; and

(iii) the gripped ends respectively include the end face A and the end face B, and a stress is applied by the grippers to the part of the piezoelectric laminate between the end faces A and B.

2. The piezoelectric vibrator described in claim 1, wherein the shape of the piezoelectric laminate is a tape.

3. The piezoelectric vibrator described in claim 1, wherein the grippers gripping the ends are fixed on a diaphragm and the stress applied to the piezoelectric laminate by the grippers is a tensile stress.

4. The piezoelectric vibrator described in claim 3, wherein the end faces A and B are at the ends of the piezoelectric laminate in the longitudinal direction.

5. The piezoelectric vibrator described in claim 1, wherein the stress applied to the piezoelectric laminate by the grippers is a compressive stress.

6. The piezoelectric vibrator described in claim 5, wherein the positions of the grippers at the ends are fixed.

7. The piezoelectric vibrator described in claim 5, wherein the positions of the grippers at the ends are movable according to expansion and contraction of the piezoelectric laminate.

8. The piezoelectric vibrator described in claim 3, wherein the end faces A and B are at the ends of the piezoelectric laminate parallel to the longitudinal direction.

9. The piezoelectric vibrator described in claim 1, wherein the number of the oriented film layers in the piezoelectric laminate is three or larger.

10. The piezoelectric vibrator described in claim 1, wherein the oriented film layers each have a thickness of 25 μ

m or less.

11. The piezoelectric vibrator described in claim 1, wherein each of the oriented film layers is at least a kind selected from the group consisting of an oriented film layer L made of a resin L containing a poly-L-lactic acid as the main component and an oriented film layer D made of a resin D containing a poly-D-lactic acid as the main component.

12. The piezoelectric vibrator described in claim 11, wherein the direction of the maximum expansion and contraction of the piezoelectric laminate is parallel to or at a right angle to the end faces A and B.

13. The piezoelectric vibrator described in claim 1, wherein the conductive layers have a surface specific resistance of 1×

10⁴Ω

/□

or less.

14. The piezoelectric vibrator described in claim 1 which is used for a piezoelectric speaker.

15. The piezoelectric vibrator described in claim 1 which is used for a signal input apparatus.

16. The piezoelectric vibrator described in claim 2, wherein the grippers gripping the ends are fixed on a diaphragm and the stress applied to the piezoelectric laminate by the grippers is a tensile stress.

17. The piezoelectric vibrator described in claim 2, wherein the stress applied to the piezoelectric laminate by the grippers is a compressive stress.