JPH09266684A - Electrostatic actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To recognize a distance of displacement accurately by the number of stepping, and to eliminate the need for a sensor for measuring a position by preventing the movement of a point, where a needle is brought into contact with a stator, during the movement (rotation) of the needle. SOLUTION: Electrodes 2, 3 are installed onto the same surface of a plate- shaped stator 1 at a regular interval. Electrodes 5, 6 are mounted on a stator 4 arranged on the stator 1 at a regular space at a regular interval while being oppositely faced to the electrodes 2, 3. A plate-shaped needle 7 capable of being shifted (a reciprocation) between the electrodes 2 and 5 or the electrodes 3 and 6 is set up between the stator 1 and the stator 4. Irregular sections at regular intervals are formed to the surface of the electrode 2 or 3 or 5 or 6. According to such constitution, the needle 7 moved among the electrodes by static electricity does not slid on the electrodes at the time of movement, and an accurate distance of displacement can be acquired only by the number of the stepping of movement.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an electrostatic actuator.

[0002]

2. Description of the Related Art An electrostatic actuator generates a driving force by static electricity, and is characterized by being compact and lightweight without requiring a complicated device structure. Such electrostatic actuators are greatly expected to be applied as actuators for various micromachines in the future.

The structure of a conventional electrostatic actuator will be described below with reference to the drawings. FIG. 4 is a side view of the electrostatic actuator, and FIG. 5 is a diagram showing the relationship between the voltage applied to the electrodes of the electrostatic actuator and time.

Electrodes 102 and 103 are provided on the same surface of the stator 101 with a predetermined interval. Stator 101
The stator 104 is arranged with a predetermined interval. Electrodes 105 and 106 are provided on the stator 104 so as to face the electrodes 102 and 103 on the stator 101 with a predetermined interval. A mover 10 movable between the stator 101 and the stator 104 is provided between the stator 101 and the stator 104.
7 is provided, and one end of the mover 107 has electrodes 102 and 10
5 can be moved by electrostatic attraction, and the other end can be moved between electrodes 103 and 106 by electrostatic attraction. The mover 107 is grounded by the conductor 108. The operation of the electrostatic actuator configured in this way will be described in the following order.

(1) The initial state of the electrostatic actuator is shown in FIG. One end of the mover 107 is connected to the electrode 102,
The other end is electrostatically attracted to the electrode 103. At this time, the voltage V is applied to the electrodes 102 and 103,
No voltage is applied to the electrode 5 and the electrode 106 (see FIG. 5).
(A)).

(2) The first step of the electrostatic actuator is shown in FIG. Next, the voltage V is applied to the electrodes 102 and 106, and the electrodes 103 and 105 are
No voltage is applied (see FIG. 5 (b)). Then, one end of the mover 107 remains electrostatically adsorbed to the contact point a of the electrode 102, but the other end is electrostatically adsorbed to the electrode 106. At this time,
The movement of the mover 107 to the electrode 106 rotates clockwise (clockwise) around the contact point a, contacts the electrode 106, and is adsorbed. After the movement is completed, it is moved in the + x direction (leftward in FIG. 4) by δ as compared with before the movement.

(3) The second step of the electrostatic actuator is shown in FIG. Next, the voltage V is applied to the electrodes 105 and 106, and the electrodes 102 and 103 are
No voltage is applied (see FIG. 5 (c)). Then, the other end of the mover 107 remains electrostatically adsorbed to the contact point d of the electrode 106, but one end thereof is electrostatically adsorbed to the electrode 105. At this time,
The movement of the mover 107 to the electrode 105 rotates counterclockwise (left) about the contact point d and contacts the electrode 105,
Adsorb. After the movement, the mover 1 is different from that shown in FIG.
The whole 07 moves in the + x direction by δ.

(4) The third step of the electrostatic actuator is shown in FIG. Next, the voltage V is applied to the electrodes 103 and 105, and the electrodes 102 and 106 are
No voltage is applied (see FIG. 5 (d)). Then, one end of the mover 107 remains electrostatically adsorbed to the contact point c of the electrode 105, but the other end is electrostatically adsorbed to the electrode 103. At this time,
The mover 107 moves to the electrode 103 by rotating counterclockwise around the contact point c, contacting the electrode 103 and adsorbing it.
After the movement is completed, the position of the other end of the mover 107 is moved by δ in the + x direction, as compared with FIG. 4C showing the position of the other end of the mover 107 before the movement.

(5) The fourth step of the electrostatic actuator is shown in FIG. Next, the voltage V is applied to the electrodes 102 and 103, and the electrodes 105 and 106 are
No voltage is applied (see FIG. 5 (e)). Then, the other end of the mover 107 remains electrostatically adsorbed to the contact b of the electrode 103, but one end thereof is electrostatically adsorbed to the electrode 102. At this time,
When the mover 107 moves to the electrode 102, it rotates clockwise around the contact b, contacts the electrode 102, and adsorbs it.
After the movement is completed, the position of the mover 107 before movement is shown in FIG.
Compared with, the entire mover 107 moves in the + x direction by 2δ.

Hereinafter, (1), (2), (3), (4),
By repeating the step to (5), the mover 107 moves in the + x direction in FIG. In this way, the moving distance can be known only by measuring the number of steps of the electrostatic actuator, and a sensor for detecting the moving distance is unnecessary.

The voltage applied to each electrode may be positive or negative. Also, steps (5), (4),
When the operations (3), (2) and (1) are performed, the mover 107 is moved.
Moves in the -x direction (rightward in FIG. 4).

[0012]

However, in the above-mentioned structure, the movable member rotates clockwise around the contact point a in FIG. 4B, and the other end of the mover is electrostatically attracted to the opposing electrode. At that time, the static friction force necessary to support rotation cannot be obtained,
The direction opposite to the moving direction of the mover (+ x direction) (-x
The problem arises of moving in the direction).

Here, when the coefficient of friction of the surface of the stator is n, the distance that the mover moves in the opposite direction in one step is δ / n ((f) in FIG. 4). In FIG.
Only 4 · δ / n is moved to the right in FIG.

Therefore, the present invention has been made in view of the above-mentioned problems of the prior art. When the mover is moving (rotating), the point in contact with the stator of the mover does not move, and the moving distance is changed by the number of steps. It is an object of the present invention to provide an electrostatic actuator that can accurately recognize a position and does not need a position measurement sensor.

[0015]

In order to achieve the above-mentioned object, the present invention provides a pair of stators arranged with a predetermined gap, and a pair of stators provided on opposite surfaces of the stator to allow sliding. It is arranged between a plurality of electrodes forming a prevention part and the stator, and the gap is advanced by being attracted alternately from one side of the stator to the other side by applying a predetermined voltage to the electrodes. And a mover that

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an enlarged side view of the periphery of the stator of the first embodiment of the electrostatic actuator. The electrodes 2 and 3 are provided on the same surface of the plate-shaped stator 1 with a predetermined interval. A stator 4 is arranged at a position facing the stator 1 with a predetermined gap. Electrodes 5 and 6 are provided on the stator 4 so as to face the electrodes 2 and 3 of the stator 1 at predetermined intervals. Between the stator 1 and the stator 4, a flat plate-shaped mover 7 that can move (reciprocate) between the electrodes 2 and 5 or the electrodes 3 and 6 is provided.
One end of the mover 7 can move (reciprocate) between the electrodes 2 and 5 by electrostatic attraction, and the other end can move between the electrodes 3 and 6 by electrostatic attraction. The mover 7 is a conductor 8
Grounded by.

Further, the surface of the electrode 2 or 3 or 5 or 6 has a predetermined distance (eg, δ: δ is when the mover 7 moves (reciprocates) between the electrodes 2 and 5 or 3 and 6). In addition, a convex / concave portion (slip prevention portion) having a moving distance with respect to the moving direction of the entire mover 7 is formed. The operation of the electrostatic actuator having such a configuration will be described.

(1) The initial state of the electrostatic actuator is shown in FIG. One end of the mover 7 is electrostatically attracted to the electrode 2 and the other end is electrostatically attracted to the electrode 3. At this time, the voltage V is applied to the electrodes 2 and 3, and the voltage is not applied to the electrodes 5 and 6.

(2) The first step of the electrostatic actuator is shown in FIG. Next, the voltage V is applied to the electrodes 2 and 6.
Is applied and no voltage is applied to the electrodes 3 and 5. Then, one end of the mover 7 remains electrostatically attracted to the contact point a of the electrode 2, but the other end is electrostatically attracted to the electrode 6. At this time,
To move the mover 7 to the electrode 6, one end of the mover 7 is moved to the electrode 2
The mover 7 rotates in the clockwise direction (clockwise) around the contact point a without shifting the contact point a by being bitten into the convex and concave portions on the surface,
The other end of the mover 7 contacts the electrode 6 and is adsorbed. After the movement is completed, the other end of the mover 7 is + x by δ compared to before the movement
Direction (left in FIG. 1).

(3) The second step of the electrostatic actuator is shown in FIG. Next, the voltage V is applied to the electrodes 5 and 6.
Is applied and no voltage is applied to the electrodes 2 and 3. Then, the other end of the mover 7 remains electrostatically adsorbed to the contact point d of the electrode 6, but one end thereof is electrostatically adsorbed to the electrode 5. At this time,
The mover 7 is moved to the electrode 5 by moving the other end of the mover 7 to the electrode 6
The movable element 7 is bitten by the convex and concave portions on the surface, and rotates about the contact point d counterclockwise (left) without the contact point d being displaced, and one end of the movable element 7 comes into contact with the electrode 5 and attracts it. After the movement, the entire mover 7 is increased by δ as compared with FIG.
Move in the x direction.

(4) The third step of the electrostatic actuator is shown in FIG. Next, the voltage V is applied to the electrodes 3 and 5, and the voltage is not applied to the electrodes 2 and 6. Then, one end of the mover 7 remains electrostatically attracted to the contact point c of the electrode 3, but the other end is electrostatically attracted to the electrode 3. At this time, the mover 7 is moved to the electrode 3 by rotating one end of the mover 7 into a convex / concave portion on the surface of the electrode 5 and rotating the mover 7 counterclockwise about the contact c without shifting the contact c. Then, the other end of the mover 7 contacts the electrode 3 and adsorbs it. After the movement is completed, the position of the other end of the mover 7 before the movement is moved by δ in the + x direction as compared with FIG.

(5) The fourth step of the electrostatic actuator is shown in FIG. Next, the voltage V is applied to the electrodes 2 and 3, and the voltage is not applied to the electrodes 5 and 6. Then, the other end of the mover 7 remains electrostatically adsorbed on the contact b of the electrode 3, but one end is electrostatically adsorbed on the electrode 2. At this time, the mover 7 moves to the electrode 2 without causing the other end of the mover 7 to be caught in the convex / concave portion of the surface of the electrode 3 and the mover 7 to move the contact b clockwise about the contact b. As it rotates, one end of the mover 7 contacts the electrode 2 and adsorbs it. After the movement is completed, the position of the movable element 7 before the movement is moved by 2δ in the + x direction as compared with the case of FIG. 1A.

Hereinafter, (1), (2), (3), (4),
By repeating the steps to (5), the mover 7 is moved to the position shown in FIG.
Move in the middle + x direction. The voltage applied to each electrode may be positive or negative. Also, step (5),
When the operations (4), (3), (2), and (1) are performed, the mover 107 moves in the −x direction.

In the electrostatic actuator of the present invention as described above, the mover 7 can move without sliding on the electrodes 2, 3, 5 and 6, and only by measuring the number of steps of the mover,
The moving distance can be accurately detected.

Further, since a sensor for detecting the moving distance of the mover is unnecessary, the size and weight of the device can be reduced and the manufacturing cost can be reduced. Further, the shape of the surfaces of the electrodes 2, 3, 5, 6 may be, for example, the shape shown in FIG.

FIG. 2 is a side view of the electrodes of the first embodiment of the electrostatic actuator. FIG. 2A shows electrodes 2, 3,
The surfaces 5 and 6 are formed in a triangular shape (pyramid shape) in cross section, and the surface of the electrodes 2, 3, 5, 6 is formed in a sawtooth shape in FIG. 2B. The direction of the arrow in FIG.
Indicates the direction of travel.

The electrodes 2, 3 having the structure as shown in FIG.
In Nos. 5 and 6, when a voltage is applied to a predetermined electrode from the contact surface between the movable element 7 and the electrode 2 or 3 or 5 or 6 and the movable element 7 moves to another electrode by electrostatic attraction, the movable element 7 is moved. It is possible to make one end of the movable member 7 fixed and not to slip, and to make the other end of the movable member 7 easily separate from the electrode before movement.

Therefore, the mover 7 can be smoothly moved to another electrode, and the electrostatic actuator can be operated at high speed. Therefore, an electrostatic actuator having a high response speed can be configured, and the applied voltage for generating static electricity can be lowered, which facilitates control.

In the electrodes 2, 3, 5 and 6 having the structure shown in FIG. 2B, the moving direction of the mover 7 can be set only in the arrow direction in the figure. With such a configuration, one end of the mover 7 that is fixed when reciprocating between the electrodes does not slip, and the mover 7 can move smoothly. Furthermore, since it is movable only in one direction, it can operate at high speed when driving force is required in only one direction.
The applied voltage for generating static electricity can be lowered and the mover 7 can be easily controlled. Next, the configuration of the second embodiment of the electrostatic actuator will be described with reference to FIG.

The same components as those in the first embodiment are designated by the same reference numerals, and the duplicated description will be omitted. The feature of the second embodiment is that the mover 7 of the electrostatic actuator is connected in series, and the distance over which the mover 7 can move in one step can be made finer.

The basic structure and operation of the electrostatic actuator are the same as in the first embodiment. The plurality of (eg, two) electrostatic actuators are the movers 7 of each electrostatic actuator.
(A) and 7 (b) are connected in series by the connector 9.

Here, the pitch between the electrodes 2 and 3 and the electrodes 5 and 6 is formed with a predetermined phase difference. For example, if there are two electrostatic actuators, the electrode pitch is shifted by ½ as shown in FIG. 3B.

The operation of the second embodiment having such a configuration will be described. When one of the mover 7 (a) and the mover 7 (b) is operated, the same operation as in the first embodiment is performed. However, when the mover 7 (a) and the mover 7 (b) are operated alternately, the pitch provided on the electrodes 2 and 3 and the pitch provided on the electrodes 5 and 6 are 1/2 pitch. Since they are displaced from each other, the movers 7 (a) and 7 (b) move by a pitch difference, that is, a 1/2 pitch.

In the second embodiment having such a structure, the movers 7 (a) and 7 (b) can move without sliding on the electrodes 2, 3, 5 and 6, and the number of steps of the mover 7 can be reduced. The moving distance can be accurately detected only by measuring.

Further, since a sensor for detecting the moving distance of the movers 7 (a) and 7 (b) is unnecessary, the device can be made compact and lightweight, and the manufacturing cost can be reduced. Further, even when accuracy equal to or less than the pitch provided in the electrodes 2, 3, 5, 6 is required, highly accurate positioning can be performed by connecting a plurality of movers of the electrostatic actuator.

The present invention is not limited to the above embodiment,
It goes without saying that various modifications can be made without departing from the spirit of the invention. For example, the electrode surface does not have to be uneven, but may have any shape as long as it can prevent the mover from slipping.

[0037]

As described above, according to the present invention, it is possible to obtain an accurate moving distance of a mover without using a sensor for measuring the moving distance of the mover, and to reduce the size and weight.

[Brief description of drawings]

FIG. 1 is an enlarged side view around a stator of a first embodiment of an electrostatic actuator of the present invention.

FIG. 2 is a side view of the electrodes of the first embodiment of the electrostatic actuator of the present invention.

FIG. 3 is a side view of a second embodiment of the electrostatic actuator of the present invention.

FIG. 4 is a side view of a conventional electrostatic actuator.

FIG. 5 is a diagram showing a relationship between a voltage applied to an electrode of a conventional electrostatic actuator and time.

[Explanation of symbols]

 1, 4 Stator 2, 3, 5, 6 Electrode 7, 7 (a), 7 (b) Mover 8 Conductor 9 Connector

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Osamu Kawakami 1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Inside the Toshiba Research and Development Center, Ltd. (72) Inventor Motonari Tsutsumi Komukai, Kawasaki-shi, Kanagawa TOSHIBA-Cho No. 1 In stock company Toshiba R & D Center (72) Inventor Satoshi Aoyagi Komukai-shi, Kawasaki-shi, Kanagawa Koumu TOSHIBA-cho No. 1 Incorporation company Toshiba Research and Development Center (72) Inventor Akihiro Koga Kawasaki, Kanagawa Komukai-Toshiba-cho, Saiwai-ku, Toshiba Research & Development Center

Claims (1)

[Claims] 1. A pair of stators which are arranged with a predetermined gap, a plurality of electrodes which are provided on opposite surfaces of the stator and which form an anti-slip portion, and which are arranged between the stators. ,
An electrostatic actuator comprising a mover that advances in the gap by being attracted alternately from one side of the stator to the other side by applying a predetermined voltage to the electrode.