Piezoelectric actuator and robot

Patent metadata

Field	Value
Publication number	US-10044295-B2
Application number	US-201514695555-A
Country	US
Kind code	B2
Filing date	Apr 24, 2015
Priority date	Apr 30, 2014
Publication date	Aug 7, 2018
Grant date	Aug 7, 2018

Abstract

A piezoelectric actuator includes a piezoelectric element, a vibrating plate configured to vibrate according to application of a signal to the piezoelectric element, and a driven body driven by the vibration of the vibrating plate. The vibrating plate vibrates in a first mode according to a signal having a first frequency, vibrates in a second mode according to a signal having a second frequency, and vibrates in a third mode according to a signal having a third frequency. The first frequency and the second frequency are different. The first frequency and the third frequency are different.

First claim

What is claimed is:

1. A piezoelectric actuator comprising:
a piezoelectric element that extends in a first direction;
a vibrating plate that extends in the first direction, the vibrating plate being provided on the piezoelectric element, the vibrating plate being configured to vibrate according to application of a signal to the piezoelectric element;
a projection that is provided at an end of the vibrating plate, the projection projecting in the first direction from the end of the vibrating plate; and
a driven body driven by the vibration of the vibrating plate, the driven body being physically connected to the projection, wherein
the vibrating plate vibrates in a first mode according to a signal having a first frequency, vibrates in a second mode according to a signal having a second frequency, and vibrates in a third mode according to a signal having a third frequency,
the first frequency and the second frequency are different, and the first frequency and the third frequency are different, and
the vibration in the second mode is bending vibration, the vibration in the third mode is longitudinal vibration, and the vibration in the first mode is combined vibration of the bending vibration and the longitudinal vibration.

2. The piezoelectric actuator according to claim 1 , further comprising a plurality of electrodes provided in the piezoelectric element, wherein
when the vibrating plate is vibrated in the third mode, the signal having the third frequency is applied to the plurality of electrodes.

3. The piezoelectric actuator according to claim 2 , wherein, when the vibrating plate vibrates in the third mode, magnitude of an electric current supplied to the piezoelectric element is controlled.

4. The piezoelectric actuator according to claim 1 , further comprising a plurality of electrodes provided in the piezoelectric element, wherein
when the vibrating plate vibrates in the third mode, the signal having the third frequency is applied to a part of the plurality of electrodes.

5. The piezoelectric actuator according to claim 1 , wherein
the driven body is rotatably connected to the projection, and
a vibrating direction of the vibration in the third mode in a contact portion of the vibrating plate with the projection is a direction toward a rotation center of the driven body.

6. The piezoelectric actuator according to claim 1 , wherein
the driven body is movably connected to the projection, and
a moving direction of a contact portion of the driven body with the projection and a vibrating direction of the vibration in the third mode are orthogonal to each other.

Assignees

• Seiko Epson Corp

Inventors

• Kamijo Koichi
• Miyazawa Osamu

Classifications

• H02N2/026

  by pressing one or more vibrators against the driven body · CPC title

• H02N2/103

  by pressing one or more vibrators against the rotor · CPC title

• H02N2/004 Primary

  Rectangular vibrators · CPC title

• H02N2/0075

  Electrical details, e.g. drive or control circuits or methods · CPC title

• H02N2/006

  Elastic elements, e.g. springs (in general F16F1/00) · CPC title