JPH09168285A - Electrostatic microactuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic microactuator which is capable of holding a stable operation of a moving element even under the low speed condition and can be applied to an artificial muscle, etc., by filling the area between the moving element and fixed electrode with a fluid having high dielectric strength and viscosity and forming the moving element in the form of stable fluid. SOLUTION: A plurality of rotors 6 in the filled fluid 5 having high viscosity are arranged in parallel with the predetermined interval in such a manner that the moving directions are reverged with each other. One end of the rotors 6 in the same direction is supported individually by supporting means 11 in both sides and these supporting means 11 on both sides are coupled with spring members 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic microactuator in which movement of a moving element is remarkably stabilized by enclosing a highly viscous fluid between the moving element and a fixed electrode.

[0002]

2. Description of the Related Art There has been almost no development of electronic and electrical equipment which applies static electricity as a driving force. The most important reason is that the energy density is smaller in order than in electronic and electrical equipment that applies electromagnetism.

With respect to this problem, it has been revealed in recent years that the drawback can be compensated for by making the device itself microsized, and therefore, recently, the use of static electricity as a driving source of a microactuator is being studied. However, according to Arnshaw's theorem that a system using static electricity always has motion instability, some means for obtaining stability in the system is required.

[0004] Therefore, a clutch acting in a direction perpendicular to the moving direction of the moving element in the electrostatic microactuator.
Conventionally, various methods have been proposed for stabilizing the system against the Ron force.

[0005] For example, there is a method of providing a mechanical bearing, but this becomes less feasible and less reliable as the size of the system becomes smaller. In addition, there is a method using magnetic levitation, but this method does not become a predominantly strong magnetic force in a micro region. In this respect, in the method utilizing the Meissner effect by the superconducting substance, the Meissner effect itself is essentially a powerful force in the micro region, but the cost increases due to the preparation of liquid helium, liquid nitrogen or the like. There is also a method of utilizing ultrasonic levitation, but since the wavelength is several mm, there is a problem that the micro size of the system is limited.

[0006]

According to the present invention, a high-viscosity fluid having a high dielectric constant is enclosed between a moving element and a fixed electrode, and the moving element is formed into a fluid-stable shape.
Provided is an electrostatic microactuator capable of retaining a stable motion of a moving element even at a low speed of 10 mm / sec or less and applicable to an artificial muscle.

Therefore, in the electrostatic microactuator of the present invention, basically, a highly viscous fluid is enclosed between the moving element and the fixed electrode, and the moving element is formed into a fluid stable shape. When the mover is configured to maintain stable motion even at low speed, the movers placed in the enclosed high-viscosity fluid are parallel to each other with the required gap so that their moving directions are opposite to each other. One end of each of the movers in the same direction is separately supported by the supports on both sides, and the two supports are connected by a spring component.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. In the electrostatic microactuator of the present invention, a high-viscosity fluid having a high dielectric constant is enclosed between the moving element and the fixed electrode, and the moving element is formed into a fluid-stable shape to move the element. The feature is that the stable state of the mover can be maintained even if the speed of the mover is not high.

For example, in a head of a hard disk drive or the like, a stable state is relatively obtained by flying the head by increasing the rotational speed of the disk even in a gas of low viscosity. According to the present invention, the same stability as that of the head of a hard disk drive is obtained for the motion stability of a moving element in an electrostatic microactuator by maintaining the Reynolds number of the system in a stable range. It is.

As an example, the speed of the moving element is 1 to 10 m.
m / sec, kinematic viscosity of highly viscous fluid is 10-3 m2 / sec
In the case of (1), if the gap is on the order of 100 μm or less, the Reynolds number in the system becomes sufficiently smaller than the critical Reynolds number (up to 1000), so that the gap becomes sufficiently laminar and the motion stability of the moving element can be expected. There was found.

FIG. 1 shows an electrostatic microactuator of the present invention.
FIG. 3 is a view for explaining the concept of the data type, in which a fixed body 7 is composed of a plurality of fixed electrodes 1 and an electrically insulating layer 2, and each fixed electrode 1 is fixedly arranged on one surface of the electrically insulating layer 2. The two fixed bodies 7 are arranged in parallel at a required interval so that the fixed electrodes 1 face each other, and the moving element 6 is arranged between the fixed electrodes 1 arranged facing each other. Mover 6
Is configured to have a plurality of moving element electrodes 4 embedded in the electrically insulating layer 3. An insulating high-viscosity fluid 5 made of silicon-based oil, fluorine-based oil, or the like is sealed in the gap between the opposed fixed electrodes 1 where the movers 6 are arranged.

The moving element 6 is formed in a step shape or a taper shape so as to have a positive pressure distribution in the gap between the fixed electrode 1 and the moving element 6, so that the dynamic pressure levitation effect can be expected. The pressure generated in the gap between the fixed electrode 1 and the moving element 6 is
Is a plate-like step shape, as shown in FIG. 2. In the two-dimensional model, a triangular area indicated by oblique lines is a pressure distribution 8 and is a total pressure applied to one surface of the moving element 6.
This total pressure is a function of the gap size, and the system retains the property that the smaller the gap, the greater the total pressure.

It is understood that this qualitative phenomenon is that a force acts to push the moving element 6 back to the equilibrium position when the moving element 6 approaches the upper or lower fixed electrode 1, and is useful for stabilizing the system. Is. However, the restoring force depends on the electrode 4 of the moving element 6.
It is a requirement that it be greater than the Coulomb force generated between the electrode and the fixed electrode 1. However, this restoring force, which is the sum of the damping force and the dynamic pressure levitation force, increases dramatically as the gap size decreases qualitatively. On the other hand, the order becomes larger. Thus, in the case of microsystems, this requirement is almost always met automatically.

FIG. 3 is a phase play intended to prove the qualitative phenomenon of the movement of the mover 6 by the stability theory.
FIG. As the analysis conditions in this figure, the size of the moving element 6 is 30 mm × 40 mm, and the average gap size is 7 mm.
0 μm, the viscosity of the fluid 5 is 0.8 Pas, and
The speed of the moving element 6 was 1 mm / sec. The horizontal axis P in FIG. 3 represents the dimensionless position of the moving element 6, the vertical axis V represents the dimensionless velocity of the moving element 6, and the broken line S at the center represents the equilibrium position of the moving element 6. .

This figure shows a qualitative state in which the moving element 6 moves in the -Y direction and has a + Y direction speed, and the moving element 6 moves in the + Y direction and has a -Y direction speed. Therefore, the moving element 6 in motion is always positioned at the equilibrium position, and thus the movement of the moving element 6 is stabilized.

FIG. 4 shows an external view of an example of the moving element 6. In this example, the moving element 6 is formed in a plate-like step shape so as to move in the right moving direction 9, but it has a fluid stable shape. If desired, a taper shape or a corrugated shape can be applied. Further, the shape can be formed symmetrically so that the moving direction is not specified unlike the reciprocating motion.

FIG. 5 is a conceptual model when the present invention is applied to an artificial muscle. In this model, a large number of movers 6 as subsystems are arranged in parallel so that they are opposite to each other, and the movers 6 in the same direction are in contact with the left and right support bodies 11, respectively. The macro system is connected to the spring component 10 arranged in the above to increase the number of subsystems connecting the generated force. The highly viscous fluid 5 is enclosed between these components.

According to this electrostatic microactuator, the muscle structure is in a muscle expansion state during its operation, and its energy is restored to the spring component 10. Then, when the operation is stopped, the energy restored in the spring component 10 is released and each moving element 6 is returned to the initial state.
Returns to muscle contraction.

During this repeatable operation, the moving elements 6 try to maintain their respective positions due to the repulsive action forces exerted by their step shapes. As a result, it is possible to avoid an unstable motion caused by the mover 6 attracting each other due to the Coulomb force.

[0020]

The electrostatic microactuator of the present invention
Does not require complicated electrical control of the movement of the mover or any additional equipment such as mechanical bearings, and can stabilize the movement of the mover reliably by using a highly viscous fluid like a fluid bearing. , Making it easier for the electrostatic microactuator to function as an integrated subsystem.

Therefore, such an electrostatic microactuator can be applied to a medical device, a camera, an artificial muscle, etc. by combining in series and in parallel.

Further, the electrostatic microactuator of the present invention.
According to the table, external control for stabilizing the moving element is not required, and an open control can be realized.
Since it is possible to be independent as a subsystem and it is easy to make the subsystem micro-sized, it is possible to reliably achieve the stability of the movement of the moving element by this micro-sized.

[Brief description of the drawings]

FIG. 1 is a conceptual explanatory view of an electrostatic microactuator of the present invention.

FIG. 2 is a pressure distribution diagram in the two-dimensional model of the present invention.

FIG. 3 is a phase plane diagram showing a qualitative phenomenon of movement of a moving element.

FIG. 4 is an external view of an example of a moving element.

FIG. 5 is a conceptual model when the present invention is applied to an artificial muscle.

[Explanation of symbols]

 1 Fixed Electrode 2 Electrical Insulation Layer 3 Electrical Insulation Layer 4 Moving Element Electrode 5 High Viscosity Fluid 6 Moving Element 7 Fixed Body 10 Spring Component 11 Support

Claims (1)

[Claims] 1. A plurality of moving elements arranged in a high-viscosity fluid enclosed in parallel are arranged in parallel at a required gap so that the moving directions thereof are opposite to each other, and each of the moving elements in the same direction is arranged. An electrostatic microactuator characterized in that one end is separately supported by supports on both sides, and both supports are connected by a spring component.