Vibration wave driving apparatus, and method of setting shape of support member supporting elastic member forming vibration member of vibration wave driving apparatus

• US 20030107299A1
• Filed: 12/03/2002
• Published: 06/12/2003
• Est. Priority Date: 12/07/2001
• Status: Active Grant

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Yamamoto, Shinji, Mori, Takao, Fujimoto, Kosuke, Nishimura, Mitsuo
• Granted Patent: US 7,245,058 B2
• Time in Patent Office: Days
• US Class Current: 310/323.03
• CPC Class Codes: H02N 2/163 Motors with ring stator

Abstract

The invention relates to a vibration wave driving apparatus which comprises a vibration member in which an electro-mechanical energy conversion element is fixed to the elastic member, and a contact member pressed against a sliding part provided in the vibration member, so as to be kept in contact therewith, and which is configured to supply alternating signals in a predetermined driving frequency band to the electro-mechanical energy conversion element, thereby generating a predetermined natural vibration mode in the elastic member to drive the contact member. In the apparatus, the natural vibration mode is generated in the elastic member, a natural frequency of another vibration mode different from the natural vibration mode is detected, and a stiffness of the support member is altered if the natural frequency of the other vibration mode detected is included in the driving frequency band.

Claims

1. A vibration wave driving apparatus comprising:

a vibration member comprising an electro-mechanical energy conversion element and an elastic member to which the electro-mechanical energy conversion element is fixed; and

a contact member pressed against the vibration member so as to be kept in contact therewith,

wherein alternating signals in a predetermined driving frequency band are supplied to the electro-mechanical energy conversion element whereby the vibration member generates a driving vibration for moving the contact member and wherein a natural frequency of another vibration different from the driving vibration is not included in the driving frequency band.

2. The vibration wave driving apparatus according to claim 1, wherein in the vibration member there exist a mode of generating another vibration having a natural frequency in a frequency band higher than the driving frequency band and a mode of generating another vibration having a natural frequency in a frequency band lower than the driving frequency band, and

wherein the driving frequency band includes a frequency at which a frequency response gain to excitation at the contact member in the mode of generating the other vibration having the natural frequency in the frequency band higher than the driving frequency band is equal to that in the mode of generating the other vibration having the natural frequency in the frequency band lower than the driving frequency band.

3. The vibration wave driving apparatus according to claim 1, wherein the elastic member comprises a ring-shaped vibration part, a fixed part for attaching the elastic member to another member, and a support part for coupling the vibration part to the fixed part, and wherein a stiffness of the support part on the fixed part side is different from that on the vibration part side.

4. The vibration wave driving apparatus according to claim 1, wherein the elastic member comprises a ring-shaped vibration part, a fixed part for attaching the elastic member to another member, and a support part for coupling the vibration part to the fixed part, and wherein a stiffness of a portion of the support part with a greater strain than that of the other portion in the other vibration is different from a stiffness of the other portion of the support part.

5. The vibration wave driving apparatus according to claim 1, wherein the elastic member comprises a ring-shaped vibration part in contact with the contact member and wherein the vibration part is fixed to a plurality of ring-shaped support members.

6. The vibration wave driving apparatus according to claim 1, wherein the elastic member comprises a ring-shaped vibration part in contact with the contact member and wherein the vibration part is fixed to a ring-shaped support member of a width narrower than the vibration part.

7. The vibration wave driving apparatus according to claim 1, wherein the elastic member comprises a ring-shaped vibration part in contact with the contact member and wherein the other vibration is a torsional vibration of twisting the vibration part with respect to an axis on a circle concentric with the vibration part.

8. The vibration wave driving apparatus according to claim 7, wherein a resultant force of a frictional force between the vibration part and the contact member and a pressing force of pressing the contact member acts on a sliding part where the vibration member is in contact with the contact member, and an axis of the torsional vibration is located on an extension of the resultant force acting on the sliding part.

9. The vibration wave driving apparatus according to claim 1, wherein a natural frequency of a first-order mode of the other vibration is set in a band higher than the driving frequency band.

10. A vibration wave driving apparatus which comprises a vibration member comprising an elastic member to which an electro-mechanical energy conversion element is joined, and a contact member kept in contact with the elastic member, and in which alternating signals in a predetermined driving frequency band are supplied to the electro-mechanical energy conversion element of the vibration member, thereby generating a driving vibration in the elastic member to drive the contact member, the vibration wave driving apparatus comprising:

frequency adjusting means which supports the elastic member so that a natural frequency of a mode of generating another vibration different from the driving vibration in the vibration member is not included in the driving frequency band.

11. The vibration wave driving apparatus according to claim 10, wherein in the vibration member there exist another vibration mode having a natural frequency in a frequency band higher than the driving frequency band and another vibration mode having a natural frequency in a frequency band lower than the driving frequency band, and

wherein the frequency adjusting means supports the elastic member so that the driving frequency band includes a frequency at which a frequency response gain to excitation at the contact member in the mode of generating another vibration having the natural frequency in the frequency band higher than the driving frequency band is equal to that in the mode of generating another vibration having the natural frequency in the frequency band lower than the driving frequency band.

12. The vibration wave driving apparatus according to claim 10, wherein the elastic member is of ring shape and the frequency adjusting means supports an internal region of the elastic member, and

wherein the frequency adjusting means is formed so that a stiffness of a portion with greater strain in the other vibration is different from that of the other portion.

13. The vibration wave driving apparatus according to claim 10, wherein the elastic member comprises a ring-shaped vibration part in contact with the contact member and wherein the frequency adjusting means secures the vibration part with a plurality of ring-shaped support members.

14. The vibration wave driving apparatus according to claim 10, wherein the elastic member comprises a ring-shaped vibration part in contact with the contact member and wherein the frequency adjusting means secures the vibration part with a ring-shaped support member of a width narrower than the vibration part.

15. A method of setting a shape of a support member fixed to an elastic member and supporting the elastic member, in a vibration wave driving apparatus which comprises a vibration member in which an electro-mechanical energy conversion element is fixed to the elastic member, and a contact member pressed against a sliding part provided in the vibration member, so as to be kept in contact therewith, and which is configured to supply alternating signals in a predetermined driving frequency band to the electro-mechanical energy conversion element, thereby generating a predetermined natural vibration mode in the elastic member to drive the contact member, said method comprising:

a step of generating the natural vibration mode in the elastic member and detecting a natural frequency of another vibration mode different from the natural vibration mode; and

a step of altering a stiffness of the support member if the natural frequency of the other vibration mode is included in the driving frequency band.

16. The method according to claim 15, wherein when the natural frequency of the other vibration mode is raised, a thickness of the support member is increased in order to alter the stiffness of the support member.

17. The method according to claim 15, wherein when the natural frequency of the other vibration mode is lowered, a thickness of the support member is decreased in order to alter the stiffness of the support member.

18. The method according to claim 15, wherein when the natural frequency of the other vibration mode is raised, a stiffness of a portion of the support member with greater strain in the other vibration mode is increased in order to alter the stiffness of the support member.

19. The method according to claim 15, wherein when the natural frequency of the other vibration mode is lowered, a stiffness of a portion of the support member with greater strain in the other vibration mode is decreased in order to alter the stiffness of the support member.

20. A method of setting a shape of a support member fixed to an elastic member and supporting the elastic member, in a vibration wave driving apparatus which comprises a vibration member in which an electro-mechanical energy conversion element is fixed to the elastic member, and a contact member pressed against a sliding part provided in the vibration member, so as to be kept in contact therewith, and which is configured to supply alternating signals in a predetermined driving frequency band to the electro-mechanical energy conversion element, thereby generating a predetermined natural vibration mode in the elastic member to drive the contact member, said method comprising:

a step of generating the natural vibration mode in the elastic member and detecting a natural frequency of another vibration mode different from the natural vibration mode; and

a step of altering a fixing position between the support member and the elastic member if the natural frequency of the other vibration mode is included in the driving frequency band.

21. The method according to claim 20, wherein when the natural frequency of the other vibration mode is raised, the support member is fixed at a position where displacement is large in the other vibration mode in the elastic member.

22. The method according to claim 20, wherein when the natural frequency of the other vibration mode is lowered, the support member is fixed at a position where displacement is small in the other vibration mode in the elastic member.