PRESSING DETECTOR AND ELECTRONIC DEVICE

• US 20180356912A1
• Filed: 08/22/2018
• Published: 12/13/2018
• Est. Priority Date: 03/10/2016
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Yamaguchi, Yoshihiro
• Granted Patent: US 10,656,729 B2
• Time in Patent Office: Days
• CPC Class Codes: G01L 1/16 using properties of piezoelectric devices
• CPC Class Codes: G01L 1/2287 constructional details of the strain gauges adjustable resistors H01C10/00
• CPC Class Codes: G01L 5/0076 Force sensors associated with manufacturing machines G01L5/0066, G01L5/0071 and B23Q17/09 take precedence; for the specific machine or operation involved see relevant class, e.g. B21 - B42
• CPC Class Codes: G06F 2203/04105 Pressure sensors for measuring the pressure or force exerted on the touch surface without providing the touch position
• CPC Class Codes: G06F 3/03 Arrangements for converting the position or the displacement of a member into a coded form
• CPC Class Codes: G06F 3/03545 Pens or stylus
• CPC Class Codes: H10N 30/857 Macromolecular compositions

Abstract

A pressing detector and an electronic device that properly corrects an integrated value at any timing. An electronic writing instrument includes a housing, an operation unit, and a pressing detector, which includes a plurality of electrodes, a piezoelectric film, a base material, a strain resistive element, a base material, a ground electrode, and a circuit including a detection unit. When an operation surface is displaced due to pressing or release of pressing by an operator, a resistance value of the strain resistive element changes. As a result, the strain resistive element performs an output according to an amount of displacement of the operation surface. The detection unit can thus correct the integrated value by the output of the strain resistive element. Therefore, the pressing detector can properly correct the integrated value at any timing.

Claims

1. A pressing detector, comprising:

a piezoelectric element configured to generate an electric charge based on an amount of displacement of an operation surface;

a displacement detection element configured to generate an output value based on the amount of the displacement of the operation surface; and

a pressing detection unit configured to;

calculate an integrated value of a voltage generated by the electric charge generated by the piezoelectric element,

intermittently operate the displacement detection element, and

correct the calculated and integrated value of the voltage based on the output value generated by the displacement detection element.

2. The pressing detector according to claim 1, wherein the pressing detection unit is configured to correct the integrated value when the calculated and integrated value is equal to or less than a predetermined value.

3. The pressing detector according to claim 1, wherein the piezoelectric element overlaps with the displacement detection element as viewed from a front side of the operation surface.

4. The pressing detector according to claim 1, wherein the displacement detection element is positioned at a center of the operation surface as viewed from a front side of the operation surface.

5. The pressing detector according to claim 1, wherein the piezoelectric element comprises a polylactic acid film.

6. The pressing detector according to claim 1, wherein the displacement detection element is strain resistive circuit having a resistance value that changes proportionally based on the amount of displacement of the operation surface.

7. The pressing detector according to claim 1, wherein the displacement detection element is a Wheatstone bridge circuit configured to generate a resistance value as the output value that changes proportionally based on the amount of displacement of the operation surface.

8. The pressing detector according to claim 7, wherein the pressing detection unit intermittently operates the Wheatstone bridge circuit by intermittently applying a drive voltage thereto.

9. The pressing detector according to claim 8, wherein the pressing detection unit is configured to continuously obtain pressing data from the piezoelectric element when the Wheatstone bridge circuit is not operating, such that the pressing detection unit can continuously correct the calculated and integrated value of the voltage generated by the electric charge generated by the piezoelectric element.

10. A pressing detector, comprising:

a piezoelectric element configured to generate an electric charge by a pressing of an operation surface;

a resistive element having a resistance value that changes based on a pressing amount of the operation surface; and

a pressing detection unit configured to;

calculate an integrated value of a voltage generated by the electric charge generated by the piezoelectric element,

intermittently operate the resistive element, and

correct the calculated and integrated value of the voltage based on the resistance value of the resistive element.

11. The pressing detector according to claim 10, wherein the pressing detection unit is configured to correct the integrated value when the calculated and integrated value is equal to or less than a predetermined value.

12. The pressing detector according to claim 10, wherein the piezoelectric element overlaps with the resistive element as viewed from a front side of the operation surface.

13. The pressing detector according to claim 10, wherein the resistive element is positioned at a center of the operation surface as viewed from a front side of the operation surface.

14. The pressing detector according to claim 10, wherein the piezoelectric element comprises a polylactic acid film.

15. The pressing detector according to claim 10, wherein the resistive element is strain resistive circuit having a resistance value that changes proportionally based on the amount of displacement of the operation surface.

16. The pressing detector according to claim 10, wherein the resistive element is a Wheatstone bridge circuit having the resistance value that changes proportionally based on the amount of displacement of the operation surface.

17. The pressing detector according to claim 16, wherein the pressing detection unit intermittently operates the Wheatstone bridge circuit by intermittently applying a drive voltage thereto.

18. The pressing detector according to claim 17, wherein the pressing detection unit is configured to continuously obtain pressing data from the piezoelectric element when the Wheatstone bridge circuit is not operating, such that the pressing detection unit can continuously correct the calculated and integrated value of the voltage generated by the electric charge generated by the piezoelectric element.

19. An electronic device comprising:

a housing;

an operation unit disposed in the housing; and

a pressing detector attached to an inner wall surface of the operation unit, the pressing detector comprising;

a piezoelectric element configured to generate an electric charge based on an amount of displacement of an operation surface;

a displacement detection element configured to generate an output value based on the amount of the displacement of the operation surface; and

a pressing detection unit configured to;

calculate an integrated value of a voltage generated by the electric charge generated by the piezoelectric element,

intermittently operate the displacement detection element, and

correct the calculated and integrated value of the voltage based on the output value generated by the displacement detection element.

20. The electronic device according to claim 19, wherein the housing comprises a cylindrical shape with at least a portion of the displacement detection element curved along an inner surface of the cylindrical shape of the housing.