PIEZOELECTRIC GENERATING APPARATUS

• US 20120007470A1
• Filed: 09/13/2011
• Published: 01/12/2012
• Est. Priority Date: 03/18/2009
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: KURIHARA, Kazuaki, Umemiya, Shigeyoshi, Aoki, Tsuyoshi
• Granted Patent: US 8,207,653 B2
• Time in Patent Office: Days
• US Class Current: 310/329
• CPC Class Codes: H02N 2/186 Vibration harvesters
• CPC Class Codes: H10N 30/306 Cantilevers

Abstract

A piezoelectric generating apparatus includes a plurality of piezoelectric bodies arranged at intervals via a gap. Each of the plurality of piezoelectric bodies includes a fixed end and a free end. A first surface electrode is formed on one side of each of the plurality of piezoelectric bodies, and a second surface electrode is formed on an opposite side of each of the plurality of piezoelectric bodies. A weight spans the plurality of piezoelectric bodies and attached to the free ends of the plurality of piezoelectric bodies. The plurality of piezoelectric bodies are curved upon application of acceleration to the weight from the outside in a lateral direction.

Claims

1. A piezoelectric generating apparatus comprising:

a plurality of piezoelectric bodies arranged at intervals via a gap, each of the plurality of piezoelectric bodies having a fixed end and a free end;

a first surface electrode formed on one side of each of the plurality of piezoelectric bodies;

a second surface electrode formed on another side of each of the plurality of piezoelectric bodies; and

a weight spanning the plurality of piezoelectric bodies and attached to the free end of each the plurality of piezoelectric bodies.

2. The piezoelectric generating apparatus according to claim 1, wherein a product of a first Young'"'"'s modulus of the first surface electrode and a first thickness of the first surface electrode in a direction from the one side to the other side is greater than a product of a second Young'"'"'s modulus of the second surface electrode and a second thickness of the second surface electrode in a direction from the one side to the other side.

3. The piezoelectric generating apparatus according to claim 2, wherein the first thickness is greater than the second thickness.

4. The piezoelectric generating apparatus according to claim 2, wherein the plurality of piezoelectric bodies are made of a piezoelectric material that generates a potential difference between the first surface electrode and the second surface electrode due to a lateral piezoelectric effect caused by a change in a relative position of the weight with respect to the fixed ends.

5. The piezoelectric generating apparatus according to claim 2, wherein the fixed ends of the plurality of piezoelectric bodies are fixed to a single support portion.

6. The piezoelectric generating apparatus according to claim 5, wherein the fixed ends of the plurality of piezoelectric bodies are integrally formed on the support portion.

7. The piezoelectric generating apparatus according to claim 5, wherein the first surface electrode and the second surface electrode that are adjacent to each other via the gap are connected on a surface of the support portion.

8. The piezoelectric generating apparatus according to claim 1, wherein the weight is bonded to the free ends via an adhesive layer having a Young'"'"'s modulus smaller than that of the plurality of piezoelectric bodies.

9. The piezoelectric generating apparatus according to claim 1, wherein the plurality of piezoelectric bodies include

a first piezoelectric layer,

a second piezoelectric layer, and

an internal electrode disposed between the first piezoelectric layer and the second piezoelectric layer.

10. The piezoelectric generating apparatus according to claim 9, wherein the first piezoelectric layer and the second piezoelectric layer are made of a piezoelectric material that generates a potential difference between the first electrode and the internal electrode and between the second electrode and the internal electrode due to a lateral piezoelectric effect caused by a change in position of the weight with respect to the fixed ends.

11. The piezoelectric generating apparatus according to claim 10, wherein the first piezoelectric layer and the second piezoelectric layer have directions of polarization that are adjusted to be opposite relative to each other in an initial state.

12. The piezoelectric generating apparatus according to claim 10, wherein the first piezoelectric layer and the second piezoelectric layer have directions of polarization that are adjusted to be the same relative to each other in an initial state.

13. The piezoelectric generating apparatus according to claim 10, wherein the fixed ends of the plurality of piezoelectric bodies are integrally formed on the support portion.

14. The piezoelectric generating apparatus according to claim 13, wherein the support portion includes therein a first wire coupling a plurality of the first surface electrodes, a second wire coupling a plurality of the internal electrodes, and a third wire coupling a plurality of the second surface electrodes.

15. The piezoelectric generating apparatus according to claim 14, wherein the support portion includes a surface formed with a first terminal coupled to the first wire, a second terminal coupled to the second wire, and a third terminal coupled to the third wire.

16. The piezoelectric generating apparatus according to claim 6, wherein the plurality of piezoelectric bodies and the support portion form a single sintered body.

17. The piezoelectric generating apparatus according to claim 1, wherein the gap is filled with an insulating material having a Young'"'"'s modulus smaller than that of the plurality of piezoelectric bodies.

18. The piezoelectric generating apparatus according to claim 1, wherein the weight is made of a piezoelectric material and is formed integrally on the free ends of the plurality of piezoelectric bodies.