JP2006280180A - Electrostatic actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform positional control accurately by making electrostatic attraction and elastic force cooperate efficiently with each other thereby enabling specified high output to be taken out even from its initial state where electrostatic attraction is weak, and besides by varying the generation power of the sum of the electrostatic attraction and the elastic force thereby enabling the gap interval to balance external force to be set optionally. <P>SOLUTION: This electrostatic actuator is equipped with a fixed electrode 14 which is set at a specified interval to a mobile electrode 12. Electrostatic attraction arises between the mobile electrode and the fixed electrode. It accumulates the work by the change of the interval between the mobile electrode and the fixed electrode as elastic force. An output part 18 is driven by the force of the elastic attraction and the elastic force. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrostatic actuator that can always output a large generated force by complementing an electrostatic attractive force with elastic energy.

  There is known an electrostatic actuator that utilizes a phenomenon in which a gap interval between opposing electrodes is displaced by an electrostatic attractive force generated when a voltage is applied to a pair of opposing electrodes. In the electrostatic actuator, the electrostatic attractive force is inversely proportional to the square of the gap interval. Therefore, in order to achieve a large electrostatic attractive force, it is necessary to set the gap interval as small as possible. On the other hand, in order to obtain a large amount of displacement, it is necessary to widen the gap interval, and there is a trade-off relationship. That is, if an amount of displacement sufficient as an actuator is to be obtained, the electrostatic attractive force is small in the initial state, and a large output cannot be obtained. Moreover, the gap interval that balances the external force cannot be arbitrarily set.

  The present invention has been made in view of the above problems, and an object of the present invention is to achieve a predetermined setting even from an initial state where the electrostatic attractive force is weak by efficiently cooperating electrostatic attractive force and elastic force. An electrostatic actuator that can take out high output, and can set the gap interval that balances the external force by changing the work of electrostatic attraction and elastic force, so that the position control can be performed accurately. It is to provide.

  An electrostatic actuator according to a first aspect of the present invention is an electrostatic actuator between a first electrode, a second electrode disposed opposite to the first electrode at a predetermined interval, and the first electrode and the second electrode. An electrostatic force generating means for generating an attractive force; an elastic means for storing work due to a change in the distance between the first electrode and the second electrode as elastic energy; and the electrostatic force and the force of the elastic force. And an output unit to be driven.

  The electrostatic actuator according to a second aspect is the electrostatic actuator according to the first aspect, wherein the elastic means is a non-linear spring.

  An electrostatic actuator according to a third aspect is the electrostatic actuator according to the first aspect, wherein a gap generated to balance an external force by changing a generated force of the electrostatic attractive force and the elastic force is arbitrarily set. It is characterized by comprising generated force variable means capable of

  According to the electrostatic actuator according to the present invention, electrostatic attractive force and elastic force can be efficiently cooperated, so that a predetermined high output can be taken out even from an initial state where the electrostatic attractive force is weak. Since the work of electrostatic attraction and elastic force can be varied, position control can be performed with high accuracy.

Hereinafter, an electrostatic actuator according to the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic view showing an electrostatic actuator of a first embodiment according to the present invention. FIG. 2 is a partially exploded view of the electrostatic actuator of FIG. In the figure, an electrostatic actuator 10 includes a rectangular movable electrode 12, a fixed electrode 14 having the same rectangular shape and the same area as the movable electrode, arranged at a predetermined interval facing the movable electrode, 12 includes a non-linear spring 16 as elastic means for accumulating work due to a change in the distance between the electrode 12 and the fixed electrode 14 as elastic energy, and an output unit 18 driven by electrostatic force and elastic force. The output unit 18 is fitted in substantially the center of the movable electrode and the fixed electrode and is provided so as to be movable in the vertical direction. The elastic means may be a linear spring.

  The movable electrode 12 is provided integrally with the output unit 18. The fixed electrode 14 is provided on the upper surface 21 of the frame body 20 and can be moved up and down by four electric plungers 22 provided on the upper surface of the frame body 20. One end of each nonlinear spring 16 is fixed to the lower surface 23 of the frame body, and the other end is in contact with the movable electrode 12. A non-linear leaf spring is used as the non-linear spring, but the non-linear leaf spring can be realized by a deformed shape, a change in plate thickness, a change in spring width, a combination of a plurality of springs, etc. so that the spring constant changes in proportion to the load. . For example, as a non-linear spring, a progressive spring is used that increases the spring constant by reducing the effective span.

  When a voltage is applied to the movable electrode and the fixed electrode, an electrostatic attractive force Fe is generated between the movable electrode and the fixed electrode. The electrostatic attractive force is generated depending on the distance between the movable electrode and the fixed electrode. The non-linear spring as the elastic means accumulates work due to a change in the distance between the fixed electrode and the movable electrode as an elastic force Fs. Thus, the output unit moves due to electrostatic attraction and elastic force.

The operation of the output unit will be described in detail below with reference to FIGS.
Step 1, voltage application; the movable electrode and the fixed electrode are turned off. The movable electrode is in a compressed state of the nonlinear spring (FIG. 3). As a result, the distance between the movable electrode and the fixed electrode is large and the electrostatic attractive force is small, while the elastic force is compressed and large.

  Step 2, voltage application; the movable electrode and the fixed electrode are turned on. The movable electrode moves upward toward the fixed electrode and reaches the fixed electrode (FIGS. 4 to 5). As a result, the distance between the movable electrode and the fixed electrode becomes narrower and the electrostatic attractive force becomes larger, while the elastic force is released and becomes smaller.

  FIG. 6 is a diagram showing the output of the electrostatic actuator of FIG. In the electrostatic actuator, the electrostatic attractive force Fe works in inverse proportion to the square of the interval between the fixed electrode and the movable electrode. In the figure, the initial setting d0 has a small electrostatic attraction Fe because the distance between both electrodes is set sufficiently large. Then, as the movable electrode moves toward the fixed electrode, the distance between the two electrodes becomes narrower. Along with this, the electrostatic attractive value Fe increases. On the other hand, since the nonlinear spring is compressed by the movable electrode in the initial setting state, the elastic force Fs is large. However, when the movable electrode moves toward the fixed electrode, the distance between the two electrodes becomes narrow, and the elastic force of the spring becomes small. Since the electrostatic actuator can work with electrostatic attraction and elastic force of the spring, it generates a force of Fe + Fs.

  Further, the generated force W; (Fe + Fs) of the electrostatic attractive force Fe and the elastic force Fs can be varied. The generated force varying means is achieved by varying the applied voltage between the movable electrode and the fixed electrode, or varying the interval between the movable electrode and the fixed electrode by varying the initial position of the fixed electrode. FIG. 7 is a diagram showing generated forces W1 and W2 obtained by changing the generated force of the sum of electrostatic attractive force Fe and elastic force Fs by changing the voltage applied to the movable electrode and the fixed electrode. Here, the generated force W can be made linear by designing the elastic force Fs in accordance with the electrostatic attractive force Fe. In the figure, the electrostatic attractive force changes from Fe to Fe 'by varying the applied voltage. That is, the value of electrostatic attraction becomes large. As a result, the generated force changes from the generated force W1 (before voltage change; Fe + Fs) to the generated force W2 (after voltage change; Fe ′ + Fs). The generated force W2 (after voltage change) has a higher output curve than the generated force W1 proportional to the square of the voltage. Here, the electrode interval can be changed from the point X to the point Y. In the figure, the horizontal axis indicates the interval d. Here, the interval d0 indicates an initial setting state. The vertical axis shows the force F.

  FIG. 8 is a diagram showing the output of the electrostatic actuator when the fixed electrode is moved downward toward the movable electrode side by the electric plunger as an initial setting. By moving the fixed electrode by the distance d1 in the initial state, the electrode interval decreases from d to d ', and the electrostatic attractive force Fe increases. On the other hand, the elastic force Fs does not change, but is shifted by the distance d1. Thus, since the electrostatic actuator works with the electrostatic attractive force Fe and the elastic force Fs ′ of the spring, the electrostatic actuator has a higher generated force W2 than the generated force W1 of the electrostatic attractive force Fe and the elastic force Fs of the spring. (Electrostatic attractive force Fed + spring elastic force Fs ′) can be performed.

  Thus, if the generated force is determined by the curve of the generated force after changing the voltage, an interval d that balances with the external force can be determined according to the generated force, so that the position can be controlled by the electrostatic actuator.

  FIG. 9 is a schematic view showing an electrostatic actuator of a second embodiment according to the present invention. In the figure, the electrostatic actuator 10 elastically works by a change in the distance between the movable electrode 12, the fixed electrode 14 fixedly arranged at a predetermined interval facing the movable electrode, and the distance between the movable electrode 12 and the fixed electrode 14. A non-linear spring 16 as elastic means for storing energy and an output unit 18 driven by electrostatic attraction and elastic force are provided. The output unit 18 is provided so as to be movable in the vertical direction by inserting substantially the centers of the movable electrode and the fixed electrode.

  The movable electrode 12 is provided integrally with the output unit 18. The fixed electrode 14 is provided fixed to the upper surface 21 of the frame body 20, and the movable electrode is provided on the lower surface of the frame body 20 and is pushed upward by the four electric plungers 22. In this case, by making it possible to change the operating range of the movable electrode while keeping the relationship between the electrostatic attractive force and the spring force constant, the actuator can be used within the optimum characteristic range of the actuator with respect to the load.

  FIG. 10 shows a schematic diagram of an electrostatic actuator in which each member is disposed on a flat plate 31 and includes a piezoelectric actuator provided on the movable electrode in order to adjust the distance between the fixed electrode and the movable electrode. In the figure, the electrostatic actuator 10 elastically works by a change in the distance between the movable electrode 12, the fixed electrode 14 fixedly arranged at a predetermined interval facing the movable electrode, and the distance between the movable electrode 12 and the fixed electrode 14. A nonlinear spring 16 serving as elastic means for storing energy, an output unit 18 driven by electrostatic attraction and elastic force, and a piezo actuator 24 for changing the initial work of the movable electrode 12 are provided.

Hereinafter, the operation of the output unit of the electrostatic actuator will be described in detail with reference to FIGS.
Step 1 (start), voltage application; the movable electrode and the fixed electrode are set to the OFF state.

  Step 2, voltage application; the piezo actuator is turned on. The movable electrode moves toward the fixed electrode (FIG. 12), and the movable electrode adheres to the fixed movable electrode and stops (FIG. 13). Thus, when the movable electrode moves toward the fixed electrode, an electrostatic attractive force is generated depending on the distance between the electrodes. On the other hand, the non-linear spring releases the elastic force.

  14 and 15 are schematic views showing the nonlinear and linear structures of the movable electrode in the electrostatic actuator, respectively. In FIG. 14, the electrostatic actuator includes a fixed electrode 14 disposed on a flat plate 31 at a predetermined interval below the movable electrode 12, and has a structure for converting changes in electrostatic attraction and electrode spacing into nonlinear displacement. Have. That is, the movable electrode 12 has a leaf spring 28 and a non-linear spring pushing guide portion 26, and the guide portion here has a curve of the non-linear spring of FIG.

  In FIG. 15, the spring-shaped guide portion 30 having a linear shape, here having an inclined surface with a predetermined angle, converts the downward displacement of the movable electrode into a linear lateral displacement.

  Practical and energy saving with large generation force and displacement, electrostatic actuator with low environmental load, position control actuator, nano electrostatic actuator, near field electrostatic actuator

It is the schematic which shows the generated force of the electrostatic actuator which concerns on this invention. It is the schematic which shows the partial decomposition | disassembly of the electrostatic actuator of FIG. In FIG. 1, it is the schematic which shows generation | occurrence | production of the electrostatic actuator which turned off the applied voltage of a movable electrode and a fixed electrode. It is the schematic which shows generation | occurrence | production of the electrostatic actuator which turned on the applied voltage of a movable electrode and a fixed electrode. It is the schematic which shows the end point of the movement of an electrostatic actuator by applying the applied voltage of a movable electrode and a fixed electrode to ON. It is the schematic which shows the output of the electrostatic actuator of FIG. It is the schematic which shows the output of work variable by varying the work of electrostatic attraction force Fe and elastic force Fs. It is the schematic which shows the output of another work variable by varying the work of electrostatic attraction force Fe and elastic force Fs. It is the schematic which shows the electrostatic actuator of 2nd Example which concerns on this invention. FIG. 10 is a schematic diagram showing an electrostatic actuator using a piezo actuator in FIG. 9. In FIG. 10, it is the schematic which shows generation | occurrence | production of the electrostatic actuator which turned off the applied voltage of a movable electrode and a fixed electrode. It is the schematic which shows generation | occurrence | production of the electrostatic actuator which turned on the applied voltage of a movable electrode and a fixed electrode. It is the schematic which shows the end point of the movement of an electrostatic actuator by applying the applied voltage of a movable electrode and a fixed electrode to ON. It is the schematic which shows the nonlinear structure of the movable electrode in an electrostatic actuator. It is the schematic which shows the linear structure of the movable electrode in an electrostatic actuator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electrostatic actuator 12 Movable electrode 14 Fixed electrode 16 Non-linear spring 18 Output part 20 Frame 22 Electric plunger 24 Piezo actuator 26 Non-linear spring pushing guide part 28 Leaf spring 30 Linear shaped spring pushing guide part 31 Flat plate

Claims (3)

A first electrode;
A second electrode disposed at a predetermined interval facing the first electrode;
Electrostatic attraction generating means for generating an electrostatic attraction between the first electrode and the second electrode;
Elastic means for accumulating work due to a change in the distance between the first electrode and the second electrode as elastic energy;
An output unit driven by the electrostatic attractive force and the elastic force;
An electrostatic actuator comprising: The electrostatic actuator according to claim 1, wherein the elastic means is a non-linear spring. 2. The electrostatic force according to claim 1, further comprising: a generated force variable means that can arbitrarily set a gap interval that balances an external force by changing a generated force of the electrostatic attractive force and the elastic force. Actuator.

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