Vibration wave motor and optical device

Patent metadata

Field	Value
Publication number	US-11043910-B2
Application number	US-201716314628-A
Country	US
Kind code	B2
Filing date	Jun 30, 2017
Priority date	Jun 30, 2016
Publication date	Jun 22, 2021
Grant date	Jun 22, 2021

Abstract

A vibration wave motor comprises: an electromechanical conversion element; an elastic body which has a drive surface on which a vibration wave is generated due to vibration of the electromechanical conversion element; and a relative motion member which makes contact with the drive surface of the elastic body and is configured to rotationally drive by the vibration wave, the electromechanical conversion element having a density of from 4.2 to 6.0×103 kg/m3, a plurality of grooves being provided on the drive surface side of the elastic body, and a value of T/(B+C) being within a range of from 1.3 to 2.8 when: depth of at least one groove of the plurality of grooves is defined as T; thickness from a base unit of the groove to a first surface is defined as B; and thickness of the electromechanical conversion element is defined as C.

First claim

What is claimed is:

1. A vibration wave motor comprising:
an electromechanical conversion element;
an elastic body which has a drive surface on which a vibration wave is generated due to vibration of the electromechanical conversion element; and
a relative motion member which makes contact with the drive surface of the elastic body and is configured to rotationally drive by the vibration wave,
the electromechanical conversion element having a density of from 4.2 to 6.0×10 3 kg/m 3 ,
a plurality of grooves being provided on the drive surface side of the elastic body, and
a value of T/(B+C) being within a range of from 1.3 to 2.8 when:
depth of at least one groove of the plurality of grooves is defined as T;
thickness from a base unit of the groove to a base surface of the elastic body with which the electromechanical conversion element makes contact is defined as B; and thickness of the electromechanical conversion element is defined as C.

2. The vibration wave motor according to claim 1 , further comprising a drive circuit configured to apply a repeatedly fluctuating drive signal to the vibration wave motor,
wherein the drive circuit is configured to change a frequency change rate of frequency sweep on the basis of the value of T/(B+C) when the vibration wave motor is started up from a speed 0 to a speed larger than the speed 0.

3. The vibration wave motor according to claim 2 , wherein the frequency change rate of the frequency sweep is equal to or less than 0.7 kHz/msec when T/(B+C) is within a range of from 1.3 to 1.7, and equal to or less than 0.5 kHz/msec when T/(B+C) is within a range of from 1.7 to 2.8.

4. The vibration wave motor according to claim 1 , wherein the value of T/(B+C) is within a range of from 1.76 to 2.8.

5. The vibration wave motor according to claim 1 , wherein the value of T/(B+C) is within a range of from 1.76 to 2.50.

6. The vibration wave motor according to claim 1 , wherein the electromechanical conversion element is made of a material having sodium potassium niobate, potassium niobate, sodium niobate or barium titanate as a principle component.

7. An optical device comprising the vibration wave motor of claim 1 .

8. A vibration wave motor comprising:
an element configured to displace due to application of voltage; and
an elastic body which makes contact with the element at a base surface and is configured to drive a moving member with a vibration wave generated on a drive surface including a groove due to displacement of the element,
the element having a density of from 4.2 to 6.0×10 3 kg/m 3 , and
a value of T/(B+C) being within a range of 1.3 to 2.8 when:
depth of the groove is defined as T;
distance from a base unit of the groove to the base surface is defined as B; and
thickness of the element is defined as C.

9. The vibration wave motor according to claim 8 , wherein thickness of the element is thickness of the groove in a depth direction.

10. The vibration wave motor according to claim 8 , further comprising a drive circuit configured to apply a repeatedly fluctuating drive signal to the vibration wave motor,
wherein the drive circuit is configured to change a frequency change rate of the drive signal on the basis of the value of T/(B+C) when the vibration wave motor is started up from a speed 0 to a speed larger than the speed 0.

11. The vibration wave motor according to claim 10 , wherein the frequency change rate is 0.7 kHz/msec when T/(B+C) is within a range of from 1.3 to 1.7, and equal to or less than 0.5 kHz/msec when T/(B+C) is within a range of from 1.7 to 2.8.

12. The vibration wave motor according to claim 8 , wherein the element is made of a material having sodium potassium niobate, potassium niobate, sodium niobate or barium titanate as a principle component.

Assignees

• Nikon Corp

Inventors

• Ashizawa Takatoshi
• Muto Azusa

Classifications

• B06B1/06

  operating with piezoelectric effect or with electrostriction (piezoelectric or electrostrictive devices per se H10N30/00) · CPC title

• H02N2/163 Primary

  Motors with ring stator · CPC title

• G02B7/08

  adapted to co-operate with a remote control mechanism · CPC title

• H02N2/142

  Small signal circuits; Means for controlling position or derived quantities, e.g. speed, torque, starting, stopping, reversing · CPC title

• H02N2/147

  Multi-phase circuits · CPC title