Displacement detection sensor and operation input device

• US 10,101,220 B2
• Filed: 05/08/2015
• Issued: 10/16/2018
• Est. Priority Date: 01/18/2013
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Ando, Masamichi, Kawamura, Hideki
• Primary Examiner(s): Gordon, Bryan
• Application Number:
  US14/707,183
• Publication Number:
  US 20150247765A1
• Time in Patent Office: 1,257 Days
• Field of Search: 31032321, 310328, 345173
• CPC Class Codes: G01L 1/16 using properties of piezoelectric devices
• CPC Class Codes: H10N 30/302 Sensors
• CPC Class Codes: H10N 30/857 Macromolecular compositions

Abstract

A displacement detection sensor has a plate member and piezoelectric sensors with a piezoelectric film of PLLA. The piezoelectric sensors are mounted on the face of the plate member on the opposite side of the operation surface thereof. Tensile stresses are generated in the entire face of the plate member at pressing the operation surface. The piezoelectric sensor is mounted so that the direction of macro tensile stress in the plate member in the region in which the piezoelectric sensor is mounted and molecular orientation direction of the piezoelectric film intersect each other at an angle of 45°. The piezoelectric sensor is mounted so that the direction of macro tensile stress in the plate member in the region in which the piezoelectric sensor is mounted and molecular orientation direction of the piezoelectric film intersect each other at an angle of approximately 45°.

Claims

1. A displacement detection sensor comprising:

a plate member having a first principal plane and a second principal plane opposite the first principal plane; and

a flat-film piezoelectric sensor disposed on the second principal plane of the plate member and including a flat piezoelectric film and a pair of detection electrodes disposed on respective principal planes of the piezoelectric film,

wherein each of the plate member and the flat-film piezoelectric sensor comprises a pair of opposing longer sides and a pair of opposing short sides,

wherein the longer sides of the flat-film piezoelectric sensor extend in a same direction as the shorter sides of the plate member,

wherein the piezoelectric film comprises a chiral polymer having a molecular orientation direction that extends in a direction parallel to the longer sides of the flat-film piezoelectric sensor, and

wherein the piezoelectric sensor is disposed at a position on the second principal plane of the plate member such that a macro direction of tensile stresses generated in the piezoelectric sensor when the first principal plane of the plate member is pressed intersects the molecular orientation direction of the chiral polymer.

2. The displacement detection sensor according to claim 1, wherein the chiral polymer is polylactic acid that is at least uniaxially stretched.

3. The displacement detection sensor according to claim 2, wherein the macro direction of the tensile stresses and the molecular orientation direction intersect at an angle of approximately 45°

.

4. The displacement detection sensor according to claim 1, wherein the piezoelectric sensor includes a plurality of the piezoelectric sensors that are disposed in different positions on the first principal plane of the plate member.

5. The displacement detection sensor according to claim 4, wherein the plurality of the piezoelectric sensors each comprises a chiral polymer having a molecular orientation direction opposite from each other and that extends in the direction parallel to the longer sides of the flat-film piezoelectric sensor.

6. The displacement detection sensor according to claim 4, wherein the plurality of the piezoelectric sensors are disposed on a shared piezoelectric film and each of the piezoelectric sensors have detection electrodes with different outputs.

7. The displacement detection sensor according to claim 6, wherein the shared piezoelectric film is disposed on substantially an entirety of the second principal plane of the plate member.

8. The displacement detection sensor according to claim 1, wherein the polylactic acid comprises mainly contains poly-L-lactic acid.

9. A displacement detection sensor comprising:

a plate member having a first principal plane and a second principal plane opposite the first principal plane; and

a flat-film piezoelectric sensor disposed on the second principal plane of the plate member and including a flat piezoelectric film and a pair of detection electrodes disposed on respective principal planes of the piezoelectric film,

wherein the piezoelectric film comprises a chiral polymer,

wherein the plate member is rectangular shaped with a length in a first direction longer than a length in a second direction that is orthogonal to the first direction,

wherein the piezoelectric sensor is rectangular shaped with a length in the first direction that is shorter than a length in the second direction,

wherein the piezoelectric sensor is disposed at a corner of the plate member such that the length in the first direction of the piezoelectric sensor extends in the first direction of the plate member, and

wherein the chiral polymer has a molecular orientation direction that extends in a direction parallel to the length of the piezoelectric sensor that extends in the second direction.

10. The displacement detection sensor according to claim 9, wherein the chiral polymer is polylactic acid that is at least uniaxially stretched.

11. The displacement detection sensor according to claim 9, wherein the piezoelectric sensor includes a plurality of the piezoelectric sensors that are disposed in different positions on the first principal plane of the plate member.

12. The displacement detection sensor according to claim 11, wherein the plurality of the piezoelectric sensors each comprises a chiral polymer having a molecular orientation direction opposite from each other and that extends in the direction parallel to the longer sides of the flat-film piezoelectric sensor.

13. The displacement detection sensor according to claim 12, wherein the plurality of the piezoelectric sensors are disposed on a shared piezoelectric film and each of the piezoelectric sensors have detection electrodes with different outputs.

14. The displacement detection sensor according to claim 13, wherein the shared piezoelectric film is disposed on substantially an entirety of the second principal plane of the plate member.

15. The displacement detection sensor according to claim 9, wherein the polylactic acid comprises mainly contains poly-L-lactic acid.

16. An operation input device comprising:

a displacement detection sensor comprising;

a plate member having a first principal plane and a second principal plane opposite the first principal plane; and

a flat-film piezoelectric sensor disposed on the second principal plane of the plate member and including a flat piezoelectric film and a pair of detection electrodes disposed on respective principal planes of the piezoelectric film,

wherein each of the plate member and the flat-film piezoelectric sensor comprises a pair of opposing longer sides and a pair of opposing short sides,

wherein the longer sides of the flat-film piezoelectric sensor extend in a same direction as the shorter sides of the plate member,

wherein the piezoelectric film comprises a chiral polymer having a molecular orientation direction that extends in a direction parallel to the longer sides of the flat-film piezoelectric sensor, and

wherein the piezoelectric sensor is disposed at a position on the second principal plane of the plate member such that a macro direction of tensile stresses generated in the piezoelectric sensor when the first principal plane of the plate member is pressed intersects the molecular orientation direction of the chiral polymer; and

a displacement detection unit configured to detect displacement from a voltage outputted from the displacement detection sensor.

17. The operation input device according to claim 16, further comprising a housing in which the first principal plane of the plate member comprises an opening and peripheral portions of the first principal plane are abutted,

wherein the piezoelectric sensor is disposed in a region where the plate member and the housing overlap in a direction orthogonal to the first principal plane.

18. The operation input device according to claim 16, wherein the chiral polymer is polylactic acid that is at least uniaxially stretched.

19. The operation input device according to claim 18, wherein the macro direction of the tensile stresses and the molecular orientation direction intersect at an angle of approximately 45°

.

20. The operation input device according to claim 16, wherein the piezoelectric sensor includes a plurality of the piezoelectric sensors that are disposed in different positions on the first principal plane of the plate member.