Piezoelectric actuator, timepiece, and electronic device

• US 20050184621A1
• Filed: 02/17/2005
• Published: 08/25/2005
• Est. Priority Date: 02/19/2004
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Kitahara, Joji, Seki, Shigeaki
• Granted Patent: US 7,109,638 B2
• Time in Patent Office: Days
• US Class Current: 310/311
• CPC Class Codes: G04C 13/12 by continuously-rotating electric motors independent clocks G04C3/16; clocks driven by synchronous motors G04C15/00
• CPC Class Codes: H02N 2/004 Rectangular vibrators
• CPC Class Codes: H02N 2/0085 Leads; Wiring arrangements
• CPC Class Codes: H02N 2/103 by pressing one or more vibrators against the rotor

Abstract

A piezoelectric actuator A has an oscillator 10 that has a flat base layer 32 and piezoelectric elements 30, 31 layered on the base layer 32 and oscillates as a result of a drive signal applied to the piezoelectric elements 30, 31, and a rotor 100 driven by vibrations from the oscillator 10. The piezoelectric actuator A includes a fastening part 11 for securing the oscillator 10, and lead substrates 14A, 14B that are secured to the fastening part 11 for applying a drive signal to the piezoelectric elements from a drive circuit 500 for driving the piezoelectric elements 30, 31. The lead substrates 14A, 14B have connecting parts 17A-17C extending to the power supply electrodes 33A, 33C and a detection electrode 34.

Claims

1. A piezoelectric actuator having an oscillator that has a flat base layer and a piezoelectric element layer on the base layer, and the oscillator vibrates as a result of a drive signal applied to the piezoelectric element layer, and a driven member that is driven by vibration of the oscillator, the piezoelectric actuator comprising:

a fastening part that secures the oscillator; and

a lead substrate secured to the fastening part for applying a drive signal from a drive circuit for driving the piezoelectric element layer;

wherein the lead substrate has a conductive member that extends to an electrode on the piezoelectric element layer.

2. A piezoelectric actuator as described in claim 1, wherein:

the lead substrate comprises an insulation layer and a conductive film on the insulation layer; and

the conductive member is formed as an extension of the conductive film.

3. A piezoelectric actuator as described in claim 1, wherein the conductive member is formed as a conductive elastic member that applies pressure to the electrode.

4. A piezoelectric actuator as described in claim 1, wherein:

the lead substrate comprises a metal layer and an insulation layer or insulation sheet covering a surface of the metal layer; and

the conductive member is a spring connected to or integrally formed with the metal layer.

5. A piezoelectric actuator as described in claim 1, wherein:

the oscillator has a first piezoelectric element layer on a front side of the base layer and a second piezoelectric element layer on a back side of the base layer;

the lead substrate comprises a first lead substrate secured to a front side of the fastening part, and a second lead substrate secured to a back side of the fastening part; and

the conductive member comprises a first conductive member extending from the first lead substrate to an electrode on the first piezoelectric element layer, and a second conductive member extending from the second lead substrate to an electrode on the second piezoelectric element layer.

6. A piezoelectric actuator as described in claim 5, further comprising a conductive part that provides conductivity between the first and second lead substrates.

7. A piezoelectric actuator as described in claim 1, wherein:

the oscillator has a first piezoelectric element layer on a front side of the base layer and a second piezoelectric element layer on a back side of the base layer;

the lead substrate is flexible;

the lead substrate has a first end secured on the front side of the fastening part and a second end secured on the back side of the fastening part; and

the conductive member comprises a first conductive member extending from the first end of the lead substrate to the first piezoelectric element layer, and a second conductive member extending from the second end of the lead substrate to the second piezoelectric element layer.

8. A piezoelectric actuator as described in claim 1, further comprising a height adjusting member between the lead substrate and fastening part so that the conductive member extending from the lead substrate is higher than the piezoelectric element layer.

9. A piezoelectric actuator as described in claim 1, wherein the lead substrate is fixed to the fastening part, forming a single unit.

10. A piezoelectric actuator as described in claim 9, comprising a positioning member that positions the fastening part and lead substrate.

11. A timepiece comprising a piezoelectric actuator as described in claim 1, the timepiece further comprising:

a drive circuit for outputting a drive signal for driving the oscillator;

a power source for supplying power to the drive circuit; and

a time information unit driven by the piezoelectric actuator for displaying time information including calendar information.

12. An electronic device comprising a piezoelectric actuator as described in claim 1, the electronic device further comprising:

a drive circuit for outputting a drive signal for driving the oscillator;

a power source for supplying power to the drive circuit; and

a driven member driven by the piezoelectric actuator.