POWER-GENERATING DEVICE

• US 20150303835A1
• Filed: 10/30/2013
• Published: 10/22/2015
• Est. Priority Date: 11/19/2012
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Inventors: KAGATA, HIROSHI, KATSUMURA, HIDENORI
• Granted Patent: US 9,525,365 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H02N 2/18 producing electrical output from mechanical input, e.g. generators for measurement devices G01
• CPC Class Codes: H02N 2/186 Vibration harvesters
• CPC Class Codes: H02N 2/188 adapted for resonant operation
• CPC Class Codes: H10N 30/306 Cantilevers

Abstract

A power-generating device includes a vibration plate, a lower electrode on the vibration plate, a piezoelectric layer made of piezoelectric material on the lower electrode, and an upper electrode on the piezoelectric layer, a fixing member for supporting a fixed end of the vibration plate. The vibration plate applies compressive stress to the piezoelectric layer when the vibration plate does not vibrate. The power generating device is excellent in long-term reliability.

Claims

1. A power-generating device comprising:

a piezoelectric power-generating transducer including

a vibration plate having a free end, a fixed end, and a first main surface, the vibration plate being configured to vibrate in a direction perpendicular to the first main surface,

a first lower electrode disposed on the first main surface of the vibration plate,

a first piezoelectric layer made of piezoelectric material disposed on the first lower electrode, and

a first upper electrode disposed on the first piezoelectric layer to face the first lower electrode across the first piezoelectric layer;

a fixing member supporting the fixed end of the vibration plate;

a first output terminal connected to the first lower electrode; and

a second output terminal connected to the first upper electrode,

wherein the vibration plate applies first compressive stress to the first piezoelectric layer when the vibration plate does not vibrate.

2. The power-generating device according to claim 1, wherein the first compressive stress is directed in parallel with the first main surface of the vibration plate.

3. The power-generating device according to claim 1, wherein the piezoelectric power-generating transducer further includes a first weight disposed on the first main surface of the vibration plate at the free end of the vibration plate.

4. The power-generating device according to claim 3, wherein the first weight is made of magnetic material.

5. The power-generating device according to claim 3,

wherein the vibration plate further has a second main surface opposite to the first main surface, and

wherein the piezoelectric power-generating transducer further includes a second weight disposed on the second main surface of the vibration plate at the free end of the vibration plate.

6. The power-generating device according to claim 1, wherein an end portion of the vibration plate including the free end of the first main surface of the vibration plate is exposed from the first lower electrode.

7. The power-generating device according to claim 6,

wherein the first piezoelectric layer has a portion exposed from the first upper electrode, and

wherein the piezoelectric power-generating transducer further includes a first coating covering the exposed portion of the first piezoelectric layer.

8. The power-generating device according to claim 1, wherein an end portion of the vibration plate including the free end of the vibration plate has a thickness smaller than a thickness of a portion of the vibration plate on which the first lower electrode is disposed.

9. The power-generating device according to claim 1,

wherein the vibration plate is configured to vibrate by releasing the free end of the vibration plate after displacing the free end of the vibration plate to a certain position, and

wherein, when the free end of the vibration plate is located at the certain position, the first piezoelectric layer receives tensile force smaller than the first compressive stress.

10. The power-generating device according to claim 1, further comprising a movable element of configured to displace the free end of the vibration plate, and then, to release the free end of the vibration plate as to cause the vibration plate vibrate.

11. The power-generating device according to claim 1,

wherein the vibration plate further has a second main surface opposite to the first main surface,

wherein the piezoelectric power-generating transducer further includes:

a second lower electrode disposed on the second main surface of the vibration plate;

a second piezoelectric layer made of piezoelectric material disposed on the second lower electrode; and

a second upper electrode disposed on the second piezoelectric layer to face the second lower electrode across the second piezoelectric layer, and

wherein the vibration plate applies second compressive stress to the second piezoelectric layer when the vibration plate does not vibrate.

12. The power-generating device according to claim 11,

wherein the first piezoelectric layer and the second piezoelectric layer are polarized in an identical direction,

wherein the first output terminal is connected to the first upper electrode and the second upper electrode, and

wherein the second output terminal is connected to the first lower electrode and the second lower electrode.

13. The power-generating device according to claim 11, wherein the second compressive stress is directed in parallel with the second main surface of the vibration plate.

14. The power-generating device according to claim 11, wherein the piezoelectric power-generating transducer further includes a first weight disposed on the first main surface of the vibration plate at the free end of the vibration plate.

15. The power-generating device according to claim 14, wherein the piezoelectric power-generating transducer further includes a second weight disposed on the second main surface of the vibration plate at the free end of the vibration plate.

16. The power-generating device according to claim 15, wherein the second weight is made of elastic material.

17. The power-generating device according to claim 11, wherein an end portion of the first main surface including the free end of the first main surface of the vibration plate is exposed from the first lower electrode.

18. The power-generating device according to claim 17,

wherein the first piezoelectric layer includes a portion exposed from the first upper electrode, and

wherein the piezoelectric power-generating transducer further includes a first coating covering the exposed portion of the first piezoelectric layer.

19. The power-generating device according to claim 18,

wherein the second piezoelectric layer includes a portion exposed from the second upper electrode, and

wherein the piezoelectric power-generating transducer further includes a second coating covering the exposed portion of the second piezoelectric layer.

20. The power-generating device according to claim 11,

wherein the vibration plate is configured to vibrate by releasing the free end of the vibration plate after displacing the free end the vibration plate to a certain position,

wherein, when the free end of the vibration plate is placed at the certain position, the first piezoelectric layer receives tensile force smaller than the first compressive stress, and

wherein, when the free end of the vibration plate is at the certain position, the second piezoelectric layer receives tensile force smaller than the second compressive stress.