Vibration actuator, lens barrel and camera
To provide a vibration actuator having good driving performance even when miniaturized, and a lens barrel and camera provided with the same. A first aspect of the present invention is to provide a vibration actuator comprising, an electromechanical conversion element, having a first joining face, and which is subject to excitation, an elastic body having a second joining face which is joined to the first joining face, and a driving face which gives rise to vibration waves as a result of said excitation, and a relative moving member, having a contact face which is in pressure contact with the driving face, which is driven by the vibration waves, and which moves relative to the elastic body, wherein an outer shape of said first joining face has a shape which differs from an outer shape of said contact face.
1. A vibration actuator comprising:
an electromechanical conversion element, having a first joining face of an elliptical contour, and which is subject to excitation;
an elastic body having a second joining face of an elliptical contour which is joined to the first joining face, and a driving face which gives rise to vibration waves as a result of said excitation; and
a relative moving member of a ring shape, having a contact face of a circular contour which is in pressure contact with the driving face, which is driven by the vibration waves, and which moves relative to the elastic body.
2. The vibration actuator according to claim 1 , wherein:
in the first joining face, a width in a direction orthogonal to a progressive direction of the relative moving member differs depending on the position in the progressive direction of the relative moving member.
3. The vibration actuator according to claim 1 , wherein:
in the first joining face, a width in a radial direction of the contact face is nonuniform.
4. The vibration actuator according to claim 1 , wherein:
the outer shape of the contact face is smaller than an outer shape of the second joining face.
5. The vibration actuator according to claim 1 , wherein:
an outer shape of the driving face is smaller than an outer shape of the second joining face.
6. The vibration actuator according to claim 1 , wherein:
a short radius of the second joining face is approximately the same as a length in a direction parallel to a short radius of the driving face.
7. The vibration actuator according to claim 1 , wherein:
the second joining face has a shape which is approximately the same as the first joining face.
8. The vibration actuator according to claim 1 , wherein:
the driving face has a similar shape to the contact face.
9. A lens barrel comprising the vibration actuator according to claim 1 .
10. The lens barrel according to claim 9 , further comprising:
a lens unit driven by the vibration actuator;
a lens retaining mount which retains the lens unit; and
a housing which encloses the lens retaining mount, wherein:
the vibration actuator is positioned between the lens retaining mount and the housing.
11. A camera comprising the vibration actuator according to claim 1 .
12. The vibration actuator according to claim 1 , wherein the vibration waves generated on the driving face comprise progressive vibration waves.