JPH04112683A - Electrostatic actuator - Google Patents

Abstract

PURPOSE:To extremely shorten the rise time and increase the driving force working on a mover and improve the accuracy in positioning by forming a dielectric region, which is permanently polarized, at the face, opposed to a stator, of a mover. CONSTITUTION:First, it is set so that the electret 22 of a mover 20 may come right above the specified stator electrode 12 of a stator 10. When the voltages applied to each terminal A-C of a stator electrode 12 are all made negative, the lines of electric force directed from the mover 20 side to the stator 10 side occur, and the mover 20 is attracted by the stator 10 (a). Next, positive voltage, to A terminal, and negative voltage, to B terminal, and 0 potential, to C terminal, are applied, respectively, and the lines of electric force directed from the side of the A terminal to the side of adjacent B terminal is formed (b). As a result, the positive charge of the electret 22 is subject to the force along the lines of electric force and floats, and shifts to the right by one pitch of electrode (c). Next, all stator electrodes 12 are made negative potential, and the lines of electric force are formed, and the mover 20 is attracted by the stator 10 (d).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrostatic actuator that can be used as a drive source using electrostatic force.

[Conventional technology]

Recently, thin models have been used as drive sources for positioning devices, etc.

Electrostatic actuators of an electrostatic drive type, which can be made smaller and lighter, have come into use.

As shown in FIG. 7, this type of electrostatic actuator generally includes a stator 2 in which a plurality of band-shaped electrodes 1 are formed within an insulator, an insulator 3 placed on the stator 2, and a high-resistance material. 4
The movable element 5 includes a movable element 5, and a voltage supply circuit (not shown) that supplies multiphase voltage to each electrode of the stator 2.

In the electrostatic actuator configured in this manner, for example, three-phase voltages as shown in FIG. 7(a) are applied to each stator electrode 1. Then, after a predetermined period of time has elapsed since the start of voltage application, charges are induced at the interface between the resistor 4 and the insulator 3 at positions facing each stator electrode 1, as shown in FIG. 2B.

This charge can be replaced with a virtual charge placed at the position indicated by the dotted line in the figure (principle of virtual charge). next,
When the polarity of the voltage applied to each stator electrode is changed as shown in FIG. The charge induced in the resistor 4 is hindered by the resistance of the resistor 4, and its change is delayed. As a result, charges of the same polarity exist at opposing positions on the stator 2 side and the mover 5 side, as shown in FIG. 2(c). When such a situation occurs, the stator 2 and mover 5
The force in the direction of repelling each other to make the mover 5 levitate and the force that moves the mover 5 to the right side in the figure act, and the force moves to the right in the figure.
As shown in the figure, the mover 2 moves laterally by 11 pitches of the stator electrodes.

The sink-in electrostatic actuator that operates as described above has the advantage that it has a simple structure and can be miniaturized because it does not require an inductance. In addition, it has a large holding force in a stationary state, and if a comb-shaped electrode is used, it can be easily used as a positioning device in an open loop or closed loop.

[Problem to be solved by the invention]

However, in the electrostatic actuator described above, since the resistance of the resistor 4 of the mover 5 is high, the charge induction time from the initial state shown in FIG. 7(a) to the charge induction state shown in FIG. 7(b) is Since it takes a long time, from several seconds to several tens of seconds, there is a drawback that the initial startup is slow.

Furthermore, since the charge generated on the mover 5 is due to electrostatic induction, the charge on the mover side is determined by the potential on the stator side.
Since the driving force and charge distribution acting on the mover are limited by the stator electrodes, it has been difficult to achieve sufficient driving force and positioning accuracy.

The present invention was made in view of the above-mentioned circumstances, and an object of the present invention is to provide an electrostatic actuator that has an extremely fast rise time, can increase the driving force acting on the moving element, and can improve positioning accuracy. do.

[Means to solve the problem]

In order to achieve the above object, an electrostatic actuator according to the present invention includes a stator having an insulating substrate on which a plurality of electrodes are formed at predetermined intervals, and the surface of each of these electrodes being insulated; A permanently polarized dielectric region is formed on a surface facing the stator and is placed on a stator, and a plurality of dielectric regions are arranged at intervals corresponding to the spacing of the electrodes. and driving means for applying a multiphase voltage to the plurality of electrodes so as to form a moving electric field for moving the mover between the opposing electrodes and the dielectric region. .

[Effect]

According to the present invention, since a permanently polarized dielectric region is formed on the facing surface of the stator of the mover, there is no need to induce electric charges, and this time can be saved, so that the actuator can be driven instantly. I can do it. Furthermore, since the amount of charge on the mover can be controlled by changing the dielectric constant of the dielectric region, it is possible to achieve the optimum amount of charge that maximizes the driving force, and as a result, a large driving force can be obtained. Furthermore, since the charge distribution of the mover is a rectangular distribution depending on the dielectric region, the charge distribution area of the mover is
The electrode formation area on the stator side can be precisely aligned with the electrode formation area on the stator side, and as a result, positioning can be performed with high precision.

〔Example〕

Examples of the present invention will be described below.

FIG. 1 is a diagram showing an electrostatic actuator according to an embodiment of the present invention, and shows a cross-sectional structure.

The electrostatic actuator of this embodiment includes a stator 10, a mover 20 placed on the stator 10, and a drive circuit (not shown) for driving the actuator.

The stator 10 has a plurality of stator electrodes 1 on the surface of an insulating substrate 11.
2 are formed at predetermined intervals, and an insulating film 13 is further formed on these stator electrodes 12. Further, each stator electrode 12 is provided with voltage application terminals A to C, respectively. A three-phase drive voltage shown in FIG. 2 is applied to each stator electrode 12 from a drive circuit. The mover 20 has a permanently polarized dielectric material (hereinafter referred to as "electret") 22 formed at multiple locations on the surface of an insulating substrate 21 facing the stator 20, and a conductive film on the other surface. 23 is formed. The electret 22 has the same width as the electrode width of the stator electrode 12, and one electret 22 is formed at three pitches of the stator electrode 12. FIG. 3 shows a perspective view of the mover 10 seen from the electret forming surface side, and FIG. 4 shows a perspective view of the stator 20 seen from the back side.

Next, the manufacturing process of the electrostatic actuator configured as above will be explained.

First, the stator 10 uses a polyimide film having a width of 50 mm and a thickness of 1 mm as a substrate, and a copper electrode having a width of 50 μm and 1 pit of 100 μm is formed as the stator electrode 12 on the surface of this substrate by etching.

Next, a polyimide film having a thickness of 50 μm is deposited on the electrode to form the insulating film 13. Note that since the stator electrodes 12 are three-phase driven, they are wired so as not to interfere with each other.

On the other hand, the mover 20 uses Teflon (FEP) with a width of 50 mm and a thickness of 1 mm as a substrate, and a conductive film 23 is formed by depositing copper on one surface of the substrate by, for example, a vacuum evaporation method. Next, an electret is formed on the other surface of the substrate by a corona discharge method.

In this electret formation, as shown in FIG.
While maintaining the temperature at 00° C., the needle 30 is brought into contact with the position where the electret is to be formed, and a voltage of about 10 kV is applied. As a result, the electret 22 is formed in the desired area. The region to be made into an electret has a band shape with a width of 50 μm, and a pitch of 300 μm. That is, stator electrode 1
The shape is the same as the shape of 2.

Next, the operation of this embodiment will be explained with reference to FIG.

First, the electret 22 of the mover 20 is set to be directly above a predetermined stator electrode 12 of the stator 10. In this state, if all the voltages applied to each terminal A to C of the stator electrode 12 are set to negative voltages, as shown in FIG. 6(a),
Lines of electric force are generated from the mover 20 side toward the stator 10 side, and the mover 20 is attracted to the stator 10 (step 1).
.

Next, a positive voltage is applied to the A terminal, a negative voltage is applied to the B terminal, and a 0 potential is applied to the C terminal, and an electric force flows from the A terminal electrode side to the adjacent B terminal electrode side as shown in the same figure (b). A line is formed (step 2).

As a result, the positive charge of the electret 22 receives a force along the lines of electric force, floats, and moves rightward in the figure by one electrode pitch. The figure (c) shows the state after the movement.

Next, all the stator electrodes 12 are set to negative potential, and the same figure (
Electric lines of force as shown in d) are formed, and the mover 20 is attracted to the stator 10 (Step 3).Then, by repeating steps 1 to 3 above in the sequence shown in FIG. 20 moves to the right in the figure.

In addition, when moving the mover 20 to the left in the drawing, voltage may be applied so that the directions of the electric lines of force shown in FIGS. 6(b) and 6(c) are reversed.

As described above, according to this embodiment, the rise time can be significantly increased because the permanently polarized charges in the electret 22 are used instead of the charges induced in the movable element.

Furthermore, since the amount of charge on the electret 22, which corresponds to the amount of charge on the mover 20, can be arbitrarily given, it is possible to give an optimal amount of charge that maximizes the driving force, and an extremely large driving force can be obtained. Obtainable.

Furthermore, the charge distribution pattern induced in the mover 20 is
Conventionally, the waveform was approximately sinusoidal, and its position varied depending on the material and dimension of the stator and mover, but since the charge of the electret 22 is approximately rectangular, the position of the charge3 width and pitch can be made to accurately match the width and pitch of the stator electrodes 12, allowing highly accurate positioning.

〔Effect of the invention〕

As detailed above, according to the present invention, it is possible to provide an electrostatic actuator that has an extremely fast rise time, can increase the driving force acting on the moving element, and can improve positioning accuracy.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of an electrostatic actuator according to an embodiment of the present invention, Fig. 2 is a waveform diagram of three-phase drive voltage used in the same embodiment, Fig. 3 is a perspective view of a mover, and Fig. 4 is a perspective view of a stator, FIG. 5 is a diagram for explaining the electret forming process, FIG. 6 is a diagram for explaining the operation of the same embodiment, and FIG. 7 is for explaining the configuration and operation of a conventional electrostatic actuator. This is a diagram. DESCRIPTION OF SYMBOLS 10... Stator, 11... Insulating substrate, 12... Stator electrode, 13... Insulating film, 20... Mover, 21
...Insulating substrate, 22...Electret, 23...
・Conductive film. Applicant's representative Patent attorney Jundai Tsuboi, (C) v! J(d) Figure

Claims (1)

[Scope of Claims] A stator comprising an insulating substrate on the surface of which a plurality of electrodes are formed at predetermined intervals, and each electrode surface is insulated; It is placed in
a mover in which permanently polarized dielectric regions are formed on a surface facing the insulating substrate surface, and a plurality of the dielectric regions are arranged at intervals corresponding to the intervals between the electrodes; An electrostatic actuator comprising: driving means for applying a multiphase voltage to the plurality of electrodes so as to form a moving electric field for moving the moving element between the moving element and the body region.