PIEZOELECTRIC DEVICE

• US 20130108061A1
• Filed: 12/20/2012
• Published: 05/02/2013
• Est. Priority Date: 08/26/2010
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: A School Corporation Kansai University, Murata Manufacturing Co Limited
• Inventors: Ando, Masamichi, Tajitsu, Yoshiro, Yoshida, Mitsunobu
• Granted Patent: US 9,276,191 B2
• Time in Patent Office: Days
• US Class Current: 381/55
• CPC Class Codes: G06F 3/0414 using force sensing means to determine a position
• CPC Class Codes: G06F 3/0433 in which the acoustic waves are either generated by a movable member and propagated within a surface layer or propagated within a surface layer and captured by a movable member
• CPC Class Codes: H04R 17/00 Piezoelectric transducers; Electrostrictive transducers piezoelectric or electrostrictive elements in general H10N30/00; details of piezoelectric or electrostrictive motors, generators or positioners H10N30/00
• CPC Class Codes: H10N 30/2047 Membrane type
• CPC Class Codes: H10N 30/802 Circuitry or processes for operating piezoelectric or electrostrictive devices not otherwise provided for, e.g. drive circuits
• CPC Class Codes: H10N 30/857 Macromolecular compositions

Abstract

A piezoelectric device is provided with a sound source IC, an amplifier for amplifying a sound source from the sound source IC, a piezoelectric speaker for generating sound based on a drive signal from amplifier, an MPU for performing a predetermined control process on the drive signal, a memory for storing temperature dependency information about the piezoelectric constant (d₁₄) and Young'"'"'s modulus E of the piezoelectric speaker, and a temperature sensor for detecting an ambient temperature. MPU has correcting unit, compares a detected result of the temperature sensor with the temperature dependency information, and performs temperature correction on the drive signal serving as an acoustic signal based on a compared result. The piezoelectric speaker outputs the acoustic signal temperature-corrected by correcting unit. Thus, it becomes possible to realize various piezoelectric devices, such as a piezoelectric speaker system, capable of preventing various input information from fluctuating even when there is a change in usage environmental temperature.

Claims

1. A piezoelectric device comprising:

a piezoelectric element comprising at least one piezoelectric body comprising a piezoelectric polmer film having electrodes on both main surfaces thereof;

an inputting unit for inputting predetermined information to said piezoelectric element;

a memory for storing temperature dependency information comprising an amount of displacement when a voltage is applied and an amount of deflection when a stress is applied to said piezoelectric element;

a temperature detector for detecting an ambient temperature; and

a correction unit for correcting the input information of said inputting unit based on a detected temperature result of the temperature detector and said temperature dependency information.

2. The piezoelectric device according to claim 1, wherein

said inputting unit comprises a sound source, and said input information comprises an acoustic signal, and

said correction unit corrects said acoustic signal based on the detected temperature result of said temperature detector and said temperature dependency information.

3. The piezoelectric device according to claim 1, wherein

said inputting unit comprises a pressing unit for applying pressure to a specific position of said piezoelectric element, and said input information includes position information and pressure information, and

said correction unit corrects said position information and said pressure information based on the detected temperature result of said temperature detector and said temperature dependency information.

4. The piezoelectric device according to claim 3, wherein an electrode formed on at least one main surface is divided into a plurality of regions.

5. The piezoelectric device according to claim 3, wherein said piezoelectric polymer material comprises poly-lactic acid.

6. The piezoelectric device according to claim 1, wherein an electrode formed on at least one main surface is divided into a plurality of regions.

7. The piezoelectric device according to claim 1, wherein the piezoelectric element includes a touch panel.

8. The piezoelectric device according to claim 1, wherein said piezoelectric polymer material comprises poly-lactic acid.

9. The piezoelectric device according to claim 1, wherein said piezoelectric element includes a piezoelectric speaker.

10. A piezoelectric device comprising:

a piezoelectric element comprising at least one piezoelectric body comprising a piezoelectric polymer film having electrodes on both main surfaces thereof;

an inputting unit for inputting predetermined information to said piezoelectric element;

a memory for storing temperature dependency information of an amount of displacement when a voltage is applied, an amount of deflection when a stress is applied, and electrostatic capacitance of said piezoelectric element;

a measuring unit for measuring the electrostatic capacitance of said piezoelectric element; and

a correction unit for correcting said input information based on said each temperature dependency information and said electrostatic capacitance measured by said measuring unit.

11. The piezoelectric device according to claim 10, wherein

said inputting unit comprises a sound source unit accumulating a sound source, and said input information comprises an acoustic signal, and

said correction unit detects a temperature of said piezoelectric element based on a measured result of said measuring unit, and the temperature dependency information of said electrostatic capacitance, and corrects the acoustic signal based on the detected temperature and the temperature dependency information of the amount of displacement when the voltage is applied, and the amount of deflection when the stress is applied, in said piezoelectric element.

12. The piezoelectric device according to claim 10, wherein

said inputting unit comprises a pressing unit for applying pressure to a specific position of said piezoelectric element, and said input information includes position information and pressure information, and

said correction unit detects a temperature of said piezoelectric element based on a measured result of said measuring unit, and the temperature dependency information of said electrostatic capacitance, and corrects said position information and said pressure information based on the detected temperature and temperature dependency information of the amount of displacement when the voltage is applied and the amount of deflection when the stress is applied in said piezoelectric element.

13. The piezoelectric device according to claim 10, wherein said measuring unit has an execution and non-execution mode, and said device further comprising a switch for switching between an execution mode of said measuring unit and a non-execution mode of said measuring unit.

14. The piezoelectric device according to claim 13, wherein said piezoelectric polymer material comprises poly-lactic acid.

15. The piezoelectric device according to claim 13, wherein said piezoelectric element includes a piezoelectric speaker.

16. The piezoelectric device according to claim 13, wherein an electrode formed on at least one main surface is divided into a plurality of regions.

17. The piezoelectric device according to claim 10, wherein said piezoelectric element includes a piezoelectric speaker.

18. The piezoelectric device according to claim 10, wherein an electrode formed on at least one main surface is divided into a plurality of regions.

19. The piezoelectric device according to claim 10, wherein the piezoelectric element includes a touch panel.

20. The piezoelectric device according to claim 10, wherein said piezoelectric polymer material comprises poly-lactic acid.