JPH0715981A - Electrostatic type actuator - Google Patents

Abstract

PURPOSE:To obtain a large amount of displacement by generating a large drive force. CONSTITUTION:A plurality of movable members with first (21A, 22A, 23A) and second (21C, 22C, and 23C) movable electrodes which are mutually insulated by insulation substrates 21B, 22B, and 23B are laminated via dielectrics 25A and 25B mutually between fixed electrodes 11A and 11B, thus increasing drive force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic actuator which obtains a driving force by utilizing an unbalance of electric field strength.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional example of this type. this is,
The comb-teeth-shaped fixed electrode F and the movable electrode M are meshed with each other with an appropriate gap provided, and a voltage is applied to both to displace the comb-teeth in the longitudinal direction and electrostatically drive in proportion to the number of comb-teeth. It is to gain strength. For example, when a voltage is applied as shown in the figure, it is displaced in the direction of arrow R1, and when a voltage is applied as described above, it is displaced in the direction of arrow R2.
In addition, H shows a support part (fixed part). The electrostatic driving force F that acts in this case is ε is the relative permittivity, d is the gap distance,
If n is the number of comb teeth, t is the tooth thickness, and V is the applied voltage, then F = ε · n · t · V ² / 2d.

FIG. 5 shows another conventional example, and FIG. 6 shows a cross section of the electrode portion. The fixing member 1 having the comb-teeth-shaped fixed electrode 11 and the comb-teeth-shaped first and second movable electrodes 21A and 21C which are insulated from each other by the insulator 21B and mesh with the comb-teeth of the fixed electrode are suitable. Two or more sets of movable members (here, three sets as shown in FIG. 6) are laminated at intervals.
And a guide member 3 for guiding the movable member 2 in only one direction.
And a voltage is applied between any one of the movable electrodes and the remaining movable electrodes via the guide member 3 to drive the movable member 2 in one direction. .

[0004]

The former is limited in the number of comb teeth that can be manufactured, the gap distance, the tooth thickness, and the like, and as a result, a large driving force cannot be obtained. On the other hand, the latter one can increase the driving force and the displacement amount more than the former one, but has a problem that the amount per unit voltage is still small and not sufficient. Therefore, an object of the present invention is to generate a large driving force and a large amount of displacement.

[0005]

In order to solve such problems, according to the present invention, a fixed member having a fixed electrode and a movable member having first and second movable electrodes insulated from each other by an insulator are provided. In the electrostatic actuator including a guide member that guides the movable member in only one direction, at least two sets of the movable member are laminated with a dielectric interposed therebetween.

[0006]

By stacking the movable members via the dielectric, the electrostatic force acting on one of the two movable electrodes in contact with the dielectric can be doubled in relative permittivity, so that the driving force can be increased. .

[0007]

1 is a perspective view showing an embodiment of the present invention, FIG.
FIG. 4 is a sectional view of an electrode portion. In these figures, 1 is a fixed member on which comb-teeth-shaped fixed electrodes 11 (11A, 11B) are formed, 2 is movable electrodes 21A, 21C, 22A, 22C,
23A, 23C, insulators 21B, 22B, 23B and dielectrics 25A, 25B, etc.
B is a guide member. That is, a movable member composed of three pairs of movable electrodes insulated from each other is arranged on the comb-teeth fixed electrode 11 so as to mesh with each other. In addition,
A spring is assumed here as the guide member, but any member having a function equivalent to this may be used.

The movable member is, for example, as shown in FIG. 2, three sets of movable electrode pairs 21A and 21C, 22A and 22C and 23 joined through insulating substrates 21B, 22B and 23B.
A and 23C are dielectrics 25 such as ceramics
A and 25B are sandwiched and laminated and joined. In addition, of the movable electrode pairs, the electrodes 21A, 22A, 23 located above
A and the electrodes 21C, 22C and 23C located below are connected to each other. When the movable member is moved by the downward force F as shown by the arrow, the fixed electrodes 11A, 11
B and electrodes 21A, 22A, 23A on each movable electrode pair
And the electrodes 21C, 22C, and
23C is applied with a voltage.

For example, when the thickness of the insulating substrates 21B, 22B and 23B is set smaller and the thickness of the dielectrics 25A and 25B is set larger than the gap between the movable member and the fixed electrode,
Fixed electrodes and movable electrodes 21A, 22A, 23 located above
A force is not generated between the movable electrode pair A, but an electrostatic force, which is an internal force, is generated between each movable electrode pair as shown by the arrow, and further between the fixed electrode and the movable electrodes 21C, 22C, 23C located below. A suction force is generated.

Focusing on this attractive force, from the Maxwell's strain force equation, the force F acting on the electrode, which is a conductor, is given by σ, which is the surface charge density, and E, the electric field on the electrode surface. Is expressed as an integral value over the entire electrode surface.

Therefore, in this embodiment, a dielectric is inserted to increase the permittivity of the conductor surface portion and increase the surface charge density to increase the force generated in the electrodes 21C, 22C and 23C. In other words, since a dielectric having a relative dielectric larger than that of air is inserted between each pair of electrodes, a remarkably large force can be generated.

FIG. 3 is a block diagram showing another embodiment of the present invention. This is because the first and second movable members 41 are laminated inside the cylindrical fixed electrode 11D with the dielectric 43 interposed therebetween.
(41A, 41B, 41C), 42 (42A, 42B,
42C) is inserted. The movable members 41, 42 are movable in one direction by the conductive guide members 3C, 3D, and the two first movable electrodes (41A, 42A) and the two second movable electrodes (41C, 42C) are ,
Internally connected while maintaining insulation from each other. In such a configuration, when the voltage V is applied as shown,
The electrostatic force described above is generated in the first movable electrodes 41A and 42A in the direction of the arrow in the figure, but since the dielectric 43 is provided at this time, the force generated in the first movable electrode 42A is It is doubled.

[0013]

According to the present invention, since the movable members are laminated via the dielectric, the electrostatic force acting on one of the two movable electrodes in contact with the dielectric is multiplied by the relative permittivity. The advantage is that the driving force can be increased.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an electrode part of FIG.

FIG. 3 is a perspective view showing another embodiment of the present invention.

FIG. 4 is a plan view showing a conventional example.

FIG. 5 is a perspective view showing another conventional example.

6 is a cross-sectional view showing an electrode portion of FIG.

[Explanation of symbols]

1 ... Fixed member, 2, 41, 42 ... Movable member, 3, 3C,
3D ... Guide member, 7A, 7B ... Bearing, 11, 11D ... Fixed electrode, 21, 22A, 23A, 41A, 21C, 22
C, 23C, 41C ... Movable electrodes, 21B, 22B, 23
B ... Insulating substrate, 25A, 25B, 43 ... Dielectric material.

Claims (1)

[Claims] 1. A static member comprising a fixed member having a fixed electrode, a movable member having first and second movable electrodes insulated from each other by an insulator, and a guide member for guiding the movable member only in one direction. An electrostatic actuator, characterized in that at least two sets of the movable members are laminated with a dielectric interposed therebetween.