Vibration actuator

Details Vibration actuator Vibration actuator

1997-04-04

2001-03-06

Dougherty, Thomas M. (Department: 2834)

Electrical generator or motor structure

Non-dynamoelectric

Piezoelectric elements and devices

C310S323130

Reexamination Certificate

active

06198202

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vibration actuator for relatively moving a contact body by a vibration produced in a vibrator.
2. Related Background Art
FIGS. 10A and 10B
are sectional views of a rod-shaped ultrasonic wave motor described in U.S. Ser. No. 340,469 as the prior art of the present invention. A vibration member
1
generates an oscillating vibration upon application of AC voltages to a piezoelectric member
3
, and the surface particles of a sliding portion B make an elliptic motion. On the other hand, a movable member
2
is in press-contact with the sliding portion B and receives a frictional driving force from the vibration member. At this time, a friction layer
1
a
on the vibration member side is an Ni-P-SiC composite galvanized layer, and is formed on the entire surface of the vibration member
1
.
In this prior art, the function required of the friction layer is given by the composite galvanized layer. However, the galvanized layer must be formed on a portion that is not associated with the required function. When the galvanized layer itself can be uniformly and smoothly formed on the entire surface, this problem is concluded as only a wasteful treatment. However, a post-treatment is required after the galvanizing treatment due to the nonuniformity of the thickness, surface roughness, and warp of the galvanized layer. As a first example, since a sliding layer
1
a
′ of the vibration member must effectively receive a minute displacement of the piezoelectric member, it must be finished to have a surface precision as high as that obtained by cutting or grinding. Thus, the sliding surface is subjected to lapping after the galvanizing treatment, in practice. The same applies to an actuator of a type in which a piezoelectric member is adhered to a vibration member. As a second example, since the resonance frequency of a vibration mode used for frictional driving must fall within a predetermined range, the galvanized portion must be removed in the post-treatment. More specifically, in the prior art shown in
FIG. 10
, the galvanized layer attached to a constricted portion
1
d
′ of the vibration member
1
must be locally removed to adjust the resonance frequency to a predetermined value. This process is discussed in detail in Japanese Laid-Open Patent Application No. 5-300768, and a detailed description thereof will be omitted.
On the other hand, some attempts have been made to utilize a resin, rubber, or the like as the friction layer. However, with this method, since the resin or rubber has a low rigidity, a molded member consisting of such a material cannot maintain a predetermined shape, and it becomes difficult to maintain high positional precision if such a member is coupled to the vibration member. On the other hand, when the molded member whose rigidity is increased by increasing its thickness is coupled to the vibration member, since the resin or rubber has large vibration attenuation, the energy loss of the motor becomes undesirably large.
SUMMARY OF THE INVENTION
The present invention has as its object to solve the above-mentioned conventional problems. As means for achieving the object of the present invention, a single conventional member is divided into two or more members, these members are separately manufactured in advance, and the members are coupled to obtain a member for a vibration member.
In other words, a functional portion required for a sliding friction layer, a portion required for magnifying a displacement of a sliding portion, and a structural portion required for a vibration member are separately formed in advance, and are then coupled to each other without disturbing the vibration performance of the vibration member.


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