JPS6395863A - Electrostatic actuator - Google Patents

Abstract

PURPOSE:To make a device of a light weight and miniaturize it, by providing an electrostatic actuator with guiding electrodes, or making electrode patterns for drive serve as electrodes for guide, too. CONSTITUTION:An electrostatic actuator is provided with a stator 1 and a movable element 2, and on the surface of the stator 1, main line electrodes 3-6 and branch line electrodes 3a-6a extended orthogonally to the electrodes 3-6 are formed as patterns. In this case, guide electrodes 7-8 are arranged. Besides, in order to retain the stator 1 and the movable element 2 with a specified space between them, balls 9 are arranged in guide grooves 10 of the stator 1, and the movable element 2 is composed to be moved in the directions of A, B shown in the figure. The drive electrodes 3-6 of the stator 1 are driven by three-phase driving pulses. Then, by using an attracting force due to an electrostatic force generated between the guide electrodes 7-8, positioning at specified positions can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrostatic actuator that moves a mover using electrostatic force.

[Prior Art] Conventional actuators mainly utilize electromagnetic force, and due to their characteristics, they must be equipped with electromagnetic coils, permanent magnets, etc., resulting in complex structures and extremely large power consumption. Ta. Therefore, the amount of heat generated by the actuator was also large.

In addition to electromagnetic force, actuators that use electrostatic force can also be considered, but the energy stored per unit area of the gap in actuators that use electrostatic force is about 10-4 to 10% compared to electromagnetic force. Since it is small at around -5, it has not been put into practical use much.

However, this is because the comparison was based on the energy stored in the air gap, and if the air gap is made very narrow, it can be expected that electrostatic force will produce an output comparable to electromagnetic force.

It is also very suitable for miniaturization. This is because in the case of electromagnetic force, the weight ratio of the yoke that guides the magnetic field into the air gap, the coil for generating the magnetic field, etc. is quite large, whereas in the case of electrostatic force, only the electrodes are required, so it is extremely lightweight. This is because it can be converted into

[Problems to be Solved by the Invention] However, when attempting to manufacture a small-sized actuator, extremely high accuracy is required in the relative positioning of the stator and mover. That is, it is necessary to maintain the relative positions of the stator and mover in an effective relationship with respect to the generation of electrostatic force. If the degree of miniaturization is large, guide mechanisms such as bearings used in conventional electromagnetic actuators cannot provide the necessary positioning accuracy, and
Frictional loads with the guide mechanism, etc., could not be ignored. Although ore bearings etc. can be used for precision applications,
Actuator characteristics are highly dependent on assembly accuracy.

For this reason, conventionally, it has been extremely difficult to perform relative positioning with small size and high precision.

[Means for Solving the Problems] The present invention has been accomplished with the object of solving the above-mentioned problems and providing an actuator that is small and has a simple configuration.

In order to achieve the above object, one embodiment of the present invention includes the following configuration.

That is, a stator in which a plurality of drive electrode parts are arranged at predetermined intervals, and a drive electrode part of the stator that is movable relative to the stator while maintaining a predetermined gap are provided on an opposing surface. An electrostatic actuator is an electrostatic actuator comprising a movable element having driving electrode portions arranged at intervals, and at least one movable element and a stator having electrodes substantially parallel to the moving direction of the movable element on opposing surfaces of each of the stator and the movable element. Equipped with a guide electrode section.

[Operation] In the above configuration, the relative positions of the stator and the movable element are positioned at predetermined positions determined by the guide electrode pattern using the attractive force caused by the electrostatic force generated between the guide electrodes.

[Example] Hereinafter, an example according to the present invention will be described in detail with reference to the drawings.

[First Embodiment] FIG. 1 is a perspective view of an embodiment according to the present invention, and in the figure,
1 is the stator, 2 is the mover, 3 is the main line 1 of φA as the pole,
3a is a branch electrode for φA that extends in a direction perpendicular to one main electrode 3 of φA, 4 is a main electrode for φB, and 4a is a branch electrode for φB that extends in both directions perpendicular to the main electrode 4 of φB.
5 is the main line electrode of φC, 5a is the technical line electrode for φC that extends in both directions orthogonal to the main line electrode 5 of φC, 6 is the other main line electrode of φA, and 6a is the other main line electrode for φA that extends in the direction orthogonal to the other main line electrode 6 of φA. The technical line electrodes 7 and 8 are guide electrodes.

An example of the structure of the electrode pattern on the surface of the stator 1 is shown in FIG. In this way, in this embodiment, the stator 1 has three drive electrodes.
Driven by phase drive pulses. Note that the number of phases is not limited to this, and smoother movement can be obtained by further increasing the number of phases.

In this embodiment, the stator 1 is made of glass, and an electrode pattern is formed on its surface by vapor deposition. Various methods such as etching can be used for patterning this electrode. Further, the stator 1 is not limited to glass, and may be made of plastics, ceramics, or the like as long as it has insulation properties. Note that although Cr is used for the electrode, various conductive metals such as Ag, Au, A-type, Cu, high melting point metals such as 7i, Ta (tantalum), or 5n0
2. Inorganic conductors such as indium tin oxide, polypyrrole,
An organic conductor such as polyaniline may be patterned using a suitable method such as vapor deposition or sputtering.

Reference numeral 9 denotes a ball which is held movably in the illustrated position by a holding means (not shown) in a guide groove 10 for holding the stator 1 and the movable element 3 at a predetermined gap. It is configured to be able to work in the direction of arrow A or arrow B in the figure.

An electrode pattern is formed on the surface of the movable element 2 shown in FIG. 1 facing the stator electrodes, and in this embodiment, the movable element 2 is made of glass. The movable member 2 is not limited to glass, but may be made of any insulating material, such as plastics such as phenol resin, ceramics, or the like.

An example of the electrode pattern of the mover 2 is shown in FIG.

As shown in the figure, the electrodes of the movable element 2 include a slit-shaped drive electrode part 23 having a constant interval, and guide electrode parts 21 on both sides.
．． 22, the guide electrode part 21.22
are patterned at positions facing the guide electrodes 7.8 of the stator 1.

In this embodiment, the pattern width of each main line and guide electrode of the stator 1 and the guide electrode portion 21, 22 of the movable element 2 are
The pattern widths of the driving electrodes of the stator 1 and the movable element 2 are set to have the same pattern pitch ratio of 3:4. This is because if the pitch of the electrodes of the movable element 2 is slightly different from the pitch of the electrodes of the stator 1, startability will be improved. By making the pattern pitch and gap smaller, the torque generated on the movable element 2 becomes larger.

Furthermore, a dielectric layer may be provided on each electrode surface for the purpose of protecting the surface, improving actuator characteristics, etc., instead of leaving the electrode exposed.

The guide electrodes 7.8 of the stator 1 of this embodiment having the above configuration are held at ground potential, and the electrode φA which is the drive electrode
When a pulse voltage as shown in Fig. 4 (the horizontal axis represents time t) is applied to each phase of 3, 6, φB4, and φC5, the electrodes on stator 1 to which the voltage of +■ is applied and the movable An attractive force acts between the movable element 2 and the drive electrode 23, and the movable element 2 is driven in the phase sequence direction of the applied voltage (in this case, the direction of arrow A in Fig. 1) in synchronization with the frequency of the applied voltage. be done.

However, it is preferable that the phase order is A, phase, B, λ, C100, A... (- means a phase shift of 180°). To move the movable element 2 in the opposite direction (arrow B direction), the phase order of the applied voltages may be reversed, and in the case of the embodiment, two of the three phases may be replaced. Also, the number of phases is shifted wJ
A signal source may be used as long as it can generate an electric field.

At this time, the present embodiment enters the state of the equivalent circuit shown in FIG. Here, C3, C4, C5, CB are the capacitances between the drive electrodes 3a, 4a, 5a, 6a and the electrode 23, respectively, C7 is the capacitance between the guide electrodes 7 and 21,
CB represents the capacitance between the guide electrodes 7 and 22.

Also, SWt, SW2, and SW3 are φA3φB, respectively.
This is a schematic representation of the drive control circuit for φC.

Referring to FIG. 5, taking as an example a state in which a driving voltage is applied to the driving electrode φB in which SW2 is connected to the power supply V side, the actuator operates so that the combined capacitance component of the actuator becomes maximum. That is, a force acts such that the combined capacitance of C4, C7, and C8 is maximized. Here, the change in C4 is mainly caused by the movement of the mover 2 in the driving direction, and C7,
The change in C8 is mainly caused by the movement of the movable element 2 in the direction perpendicular to the drive direction (guide electrode arrangement direction). That is, by forming 07 and C8 as in this embodiment, the movable body 2
are driven so that the opposing area between guide electrodes 7, 21, 8, and 22 is maximized. For this reason, the stator 1 and the mover 2 are moved in the mechanical lateral direction (in the direction perpendicular to the driving direction).
The electrostatic force acting between the guide electrodes 7, 21, 8, and 22 allows the guide electrodes to be positioned at a predetermined position determined by the electrode arrangement position without providing a guide mechanism for preventing displacement.

Although FIG. 4 shows three-phase pulses of rectangular waves that do not overlap with each other, the drive voltage waveform does not necessarily have to be a rectangular wave, and each phase may overlap.

Here, we have explained the case where a pulse voltage of (0/+V)V is applied to each phase (each electrode) of the drive electrode, but the electrode application waveform is not limited to this. Even if an alternating current voltage is applied, it is also possible to use a drive waveform that changes between a low potential VL and a high potential VH.

In addition, the above-mentioned Kiki ff! /J A method of overlapping the voltage waveform (drive pulse) applied to the electrode, or a method of constantly applying V to the electrode.
The control method of applying a voltage equal to or higher than L(VLf-0) is to compensate for the constant application of a voltage equal to or higher than a certain value to C7 and C8 shown in FIG. 5, and is a preferred embodiment of the present invention. It is.

[Second Embodiment] Although the above description has been given of an example in which special guide electrodes 7 and 8 are provided on the stator 1 side, the present invention is not limited to this, and the guide electrodes shown in FIG. 7.8 can also be omitted.

If the guide electrodes 7.8 on the stator 1 side are omitted, the electrode pattern on the movable element 2 side will be the electrode pattern shown in FIG.

In FIG. 6, 24 to 27 are guide electrode patterns, and the guide electrode 24 is one of the main power lines 8i of φA of the stator 1.
3. The guide electrode 25 is the main electrode 4 of φB, and the guide electrode 2
Reference numeral 6 denotes the main electrode 5 of φC, and the guide electrode 8i 27 is arranged so that the pattern width is the same at the opposite surface position of the other main electrode 6 of φA, and the driving electrode pattern 23a is the driving electrode pattern 23a shown in FIG. Electric g! They are arranged at the same pitch and pattern width as 23. Then, each electrode of the movable element 2 having the above electrode pattern may be maintained at the ground potential. This ground potential can be maintained by connecting a signal line (not shown) to the electrode and holding it via the signal line, or by forming the ball 10 in FIG. Make the bottom conductive and keep it at ground potential, and connect the ball 9 of the mover 2.
This electrode pattern may be extended to the contact position and held at ground potential via the ball 9.

Then, by applying the same drive potential as in the first embodiment, for example, the drive potential shown in FIG. 4, to each drive electrode of the stator 1, the stator 1 is moved in the direction of the arrow A in FIG. 1 without causing lateral wobbling. be able to.

The equivalent circuit at this time is shown in FIG.

Here, as in FIG. 5, C3°s, C4, and C5 are the drive electrodes 3a, 6a, and 4a of the stator 1 shown in FIG. 2, respectively.
, 5a and each drive electrode 23a of the movable element 2. On the other hand, C'sea + C
' 4 + C' 5 is one main line electrode 3 of φA of stator 1 and the other main line electrode 6 of φA and guide electrode 2 of mover 2
Between 4 and 27, φB main electrode 4 and guide electrode 25, φ
The capacitance of the opposing portion of each electrode between the main electrode 5 and the guide electrode 26 of C is shown. In addition, SWI~
SW3 is the same as that shown in FIG.

As shown in the figure, in this example as well, C3°a, C4, and C5 mainly contribute to the 8th shift in the driving direction of the mover 2, and the direction mainly perpendicular to the driving direction (guide electrodes 24 to 27 arrangement direction). The movement of the mover 2 contributes to C'3°a, C'4. C
' 5 are in parallel. Therefore, the same effect can be obtained by using the main electrode pattern of the drive electrode without providing a special guide electrode on the stator 1 side.

[Third Embodiment] Although all of the above explanations have been made regarding movable elements that perform linear motion, the present invention is not limited to linear motion.
It can also be applied to rotational motion. Another embodiment of the present invention in which the movable element rotates is shown in FIGS. 8 and 9.

FIG. 8 shows the electrode pattern on the stator side, and FIG. 9 shows the electrode pattern on the mover side.

In the figure, 31 is the stator, and 32 is the bearing of stator 1, which rotates 3 degrees!
It is a movable element rotatably supported by i[1145 and supported with a predetermined gap from the stator 31.

On the surface of the movable element 32 facing the stator 31, guide electrode patterns 41 to 44 as shown in FIG. 9 and drive electrode patterns 44 are arranged radially at a predetermined pitch around the rotating shaft 45. On the other hand, on the surface of the stator 31 facing the movable element 32, as shown in FIG.
, φC electrode 36, φA other electrode 8i37, and guide electrode patterns 37 to 40 are arranged as shown in the figure, and each drive electrode 33 to 36 is arranged on a concentric circumference without being lined up on a radial line centered on the bearing 30. They are arranged at predetermined intervals. The drive electrode 44 of the movable element 32 is connected to the movable element 32.
Each drive electrode 3 on the stator 31
It is configured to face any one of numbers 3 to 36.

Then, when each electrode of the movable element 32 is set at a ground potential and a driving voltage is applied to each electrode of the stator at the timing shown in FIG. 4, the movable element 32 is driven.

At this time, similarly to the first embodiment, the drive electrode 44 is connected to the movable element 3.
2, and each part of the annular guide electrode pattern 41, 42, 43 faces the annular guide electrode pattern 38, 39, 40 on the stator 31 side, so that the stator 31 and This contributes to the effect of aligning the center axis of rotation with the movable element 32.

In this embodiment, each of φA to φC corresponds to φA to φC in the previous embodiment.

When the electrodes that contribute to self-alignment are divided into multiple parts and provided in this way, the total capacitance between these electrodes (C, +C♂ in Figure 5) becomes sensitive to deviations in directions other than the drive direction of the slider. Therefore, the effect of stabilizing the position of the mover becomes greater.

Figures 8 and 9 are examples of patterns for a disk-shaped electrostatic actuator, but for easy analogy, a stator electrode pattern and a movable electrode pattern are formed on each opposing surface of a double cylinder. Thus, a cylindrical rotary actuator can be constructed.

In this case, the inner part of the double cylinder can be used as a stator and the outer part can be used as a mover (rotor), or conversely, the outer part can be used as a stator and the inner part can be used as a mover (rotor). However, in either case, the self-alignment effect of the present invention functions effectively.

[Effects of the Invention] As explained above, according to the present invention, by providing the electrostatic actuator with a guide electrode or by making the drive electrode pattern also serve as a guide electrode, the area on the stator can be improved. Since it is possible to suppress the displacement of the movable element in directions other than the driving direction, a mechanical guide mechanism can be omitted.

Therefore, when manufacturing a small actuator, P'!
Parts that require precision machining are no longer required, resulting in lighter weight and
Miniaturization and cost reduction are possible.

Further, since the movable element of the actuator is automatically placed in the optimum position during driving, there is no need for accurate positioning during assembly, making the work easier.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an embodiment according to the present invention, FIG. 2 is a diagram showing an electrode pattern of a stator of this embodiment, FIG. 3 is a diagram showing an electrode pattern of a mover of this embodiment, 4 is a timing chart of the drive voltage of this embodiment, FIG. 5 is an equivalent circuit diagram of this embodiment, FIG. 6 is a diagram showing the electrode pattern of the movable element of another embodiment according to the present invention, and FIG. 7 is an equivalent circuit diagram of another embodiment, FIG. 8 is a diagram showing the electrode pattern of the stator of still another embodiment according to the present invention, and FIG. 9 is a diagram showing the electrode pattern of the movable element of still another embodiment. It is a diagram. In the figure, 1: Stator, 2: Mover, 3 to 6, 3a. 4a, 5a, 6a, 21, 23, 23a, 33-36.
44... Drive electrode, 7, 8, 21, 22. 24-27
．． 37-43...Guide electrode, 9...Ball. Patent applicant: Canon Co., Ltd. Figure 4, Figure 5 ■ r-Qυ Procedural amendment (voluntary) December 1, 1985

Claims (4)

[Claims] (1) A stator in which a plurality of drive electrode sections are arranged at predetermined intervals, and a drive electrode section of the stator that is movable relative to the stator while maintaining a predetermined gap on the opposing surface. An electrostatic actuator comprising a movable element having driving electrode portions arranged at predetermined intervals, the electrostatic actuator comprising at least one movable element and a movable element on opposing surfaces of each of the stator in the moving direction of the movable element. An electrostatic actuator characterized by having substantially parallel guide electrode portions. (2) The electrostatic actuator according to claim 1, wherein the movable element side electrode is set to a ground potential. (3) The driving electrode portions of the stator are connected to each other in multiple phases, and the movable element is moved by the attractive force generated in the electrodes between the stator and the movable element by changing the voltage applied to each phase. An electrostatic actuator according to claim 1 or 2, characterized in that: (4) The electrostatic actuator according to any one of claims 1 to 3, wherein the guide electrode also serves as a voltage supply pattern to the drive electrode section.