Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
1999-04-26
2004-02-10
Budd, Mark O. (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
C310S323060
Reexamination Certificate
active
06690100
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a piezoelectric actuator in which a marking is formed at an electrode pattern on a piezoelectric element and a method of compensating a direction thereof.
In recent times, in the field of a micromotor, a piezoelectric actuator utilizing a piezoelectric element subjected to predetermined polarization processing has attracted attention.
In the procedure of fabricating the piezoelectric actuator, there is utilized a marking produced by forming a shape of an electrode pattern in identifying directions of polarization of respective divided electrodes in polarization processing, identifying a direction of a set position of the piezoelectric element in forming an electrode pattern for shortcircuiting, in identifying a direction of pasting a piezoelectric element on an elastic member in pasting operation, in identifying a direction of assembling a motor in assembling operation and in identifying a direction of attaching lead wires in attaching operation.
FIG. 17
shows a plane structure of a piezoelectric actuator according to a conventional example.
A piezoelectric actuator
100
according to the conventional example is installed with a piezoelectric element
101
produced by dividing a circular disk body in a fan-like shape in the peripheral direction, an electrode pattern
102
formed with electrodes
102
a
,
102
b
,
102
c
,
102
d
,
102
e
and
102
f
at every other divided portion in the fan-like shape of the piezoelectric element
101
in which the electrodes are shortcircuited at outer peripheral portions thereof, an electrode pattern
103
formed with electrodes
103
a
,
103
b
,
103
c
,
103
d
,
103
e
and
103
f
similarly in a fan-like shape in which the electrodes are shortcircuited at inner peripheral portions thereof and an entire face electrode, not illustrated, formed on a side of the piezoelectric element
101
opposed to the electrode patterns
102
and
103
, and further formed with a marking
104
in a semicircular shape at a portion of the outer peripheral portion of the electrode
102
a
in the fan-like shape of the electrode pattern
102
(for example, refer to JP-A-1-283074, JP-A-3-219681).
However, the above-described marking
104
in the semicircular shape cannot be set with an area larger than that illustrated above to avoid overlapping the entire face electrode formed on the opposed side.
Further, when the divided electrode
102
a in the fan-like shape and the piezoelectric element
101
are formed to shift from each other, there also causes a situation in which the position of the marking
104
cannot be detected by an image processing apparatus. The reason is as follows.
1) When a portion of the marking
104
rests on the outer periphery of the piezoelectric element
101
, the area of the marking
104
is extremely reduced in accordance with the radius of curvature of the circle.
2) The marking
104
is deviated from the outer periphery of the piezoelectric element
101
and the marking is not formed at all.
3) An area of a blank margin portion in a ring-like shape between the divided electrode
102
a in the fan-like shape and the outer periphery of the piezoelectric element
101
(portion not formed with the electrode pattern
102
) is widened and the marking
104
cannot be discriminated from the blank margin portion.
Further, when dirt or dust having a shape and a size similar to those of the marking
104
is adhered to the electrode pattern
102
or
103
, there poses a problem in which the correct position of the marking cannot be detected.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a piezoelectric actuator and a method of compensating a direction thereof promoting a function of identifying a marking and minimizing adverse influence on a marking even when an electrode pattern is formed to shift.
That is, according to solving means of the problem, there is provided a piezoelectric actuator characterized in that in a piezoelectric actuator having a piezoelectric element forming an electrode pattern:
wherein the electrode pattern is formed with at least one marking in a shape comprising multiple sides (When the shape is closed, a polygonal shape is constituted. The same as follows.) for determining a direction of forming the electrode pattern of the piezoelectric element.
In the above-described solving means, the shape of the marking includes a shape comprising three sides (When the shape is closed, a tetragonal shape is constituted. The same as follows.), a shape comprising four sides (When the shape is closed, a pentagonal shape is constituted. The same as follows.) or other shape comprising multiple sides. Further, the position of the marking includes that of either of cases of forming the marking at an outer peripheral portion of the electrode pattern and at inside thereof.
The piezoelectric element includes shapes of a circular disk, a ring-like shape, a polygon and the like.
According to the solving means, the area surrounded by the shape comprising multiple sides becomes larger than an area surrounded by a semicircle and accordingly, the identifying function of the marking is promoted. Further, when the marking having the shape comprising multiple sides rests on the outer periphery of the piezoelectric element, the area is reduced in accordance with an internal angle of the shape comprising multiple sides and accordingly, a rate of reducing the area is smaller than that of reducing the marking in the semicircular shape.
Further, according to the piezoelectric actuator, the marking is featured in having a shape comprising three sides.
According to the solving means, an area surrounded by the shape comprising three sides becomes larger than the area surrounded by a semicircle and accordingly, the identifying function of the marking is promoted. Further, when the marking having the shape comprising three sides rests on the outer periphery of the piezoelectric element, the area is reduced by a constant rate and accordingly, the rate of reducing the area is smaller than that of reducing the marking in the semicircular shape.
Further, there is provided a piezoelectric actuator characterized in that in a piezoelectric actuator in which a piezoelectric element is divided in a peripheral direction and electrodes are formed at divided portions at least contiguous to each other to thereby constitute an electrode pattern:
wherein at least one marking for determining a direction of forming the electrode pattern of the piezoelectric element is formed on an inner side of an outer periphery of the electrode pattern and between the electrodes contiguous to each other in the electrode pattern.
In the above-described solving means, the shape of the piezoelectric element includes any of a circular disk shape, a ring-like shape, a polygonal shape and so on. Further, the respective electrodes formed at the divided portions include either of a system for connecting leads to the respectives and a system of shortcircuiting predetermined ones of the electrodes.
The shape of the marking includes a circular shape, a semicircular shape, a shape comprising two sides, a shape comprising three sides and other shapes comprising multiple sides as well.
According to the solving means, the marking is disposed on an inner side of an outer periphery of the electrode pattern and accordingly, even when the electrode pattern rests on the outer periphery of the piezoelectric element, no adverse influence is effected and sufficient identifying performance is ensured.
Further, there is provided a piezoelectric actuator characterized in that in a piezoelectric actuator having a piezoelectric element which is divided equally by n in a peripheral direction and in which p of consecutive divided portions polarized in one direction and p of consecutive divided portions polarized in a direction reverse to the one direction are alternately arranged and electrodes are formed at n of the divided portions of the piezoelectric element:
wherein the electrode pattern is formed with m of markings for determining
Itoh Hironobu
Koroishi Keitaro
Yoshino Tomoyuki
Adams & Wilks
Budd Mark O.
Seiko Instruments Inc.
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