JPH0833361A - Electrostatic actuator - Google Patents

Abstract

PURPOSE:To obtain a compact actuator which is capable of driving with a simple DC power supply without requiring a complex wiring and a drive circuit. CONSTITUTION:A pair of stators, where two stators 1 and 2 which are provided with a tooth-shaped protrusion 11 provided at a pitch of lambda on one side surface and a continuous stator electrode 12 on at least one surface are allowed to oppose each other with a vacant space, and are shifted in the traveling direction by a pitch of lambda/2 and a traveling element 3 where protrusions 31 in the same shape as the stator electrode are provided symmetrically on both surfaces which oppose two stators while being provided in the space of a pair of stators and a continuous traveling element 32 is provided at least on the surface are provided and then insulation films 13 and 23 are provided on at least one contact surface of the stator or the traveling element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microactuator used as a driving source for a micromachine.

[0002]

2. Description of the Related Art Conventionally, as one of the electrostatic actuators, there is one which is composed of a cylindrical stator and a rotor having an outer diameter slightly smaller than the inner diameter of the stator as described below (Japanese Patent Laid-Open No. Hei 10 (1999) -264242)
4-42790). This is because the inner surface of the stator is made of metal,
The drive electrodes of the stator are formed by being divided at a constant pitch by an insulator. The outer surface of the rotor is made of metal and forms a rotor electrode. D on the drive electrode of the stator
When a voltage is continuously applied to the stator electrode by the C power supply and the switching circuit, an electrostatic attraction force works between the stator electrode and the rotor electrode, and this is used to operate the rotor.

[0003]

However, in the prior art, in order to move the rotor smoothly, it is necessary to divide the stator electrodes into a large number and to provide a wiring and a driving circuit capable of applying a voltage to all the electrodes. Therefore, there is a problem that such complicated wiring and drive circuit hinder the miniaturization of the actuator. Therefore, an object of the present invention is to provide a small-sized actuator that can be driven by a simple DC power supply that does not require complicated wiring or a drive circuit.

[0004]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides two fixings having a saw-toothed projection provided on one side with a pitch λ and having a continuous stator electrode on at least the surface thereof. A pair of stators, which are opposed to each other with a gap, and are displaced by a pitch λ / 2 in the moving direction, and the stator, which is provided in the gap of the pair of stators and faces the two stators, respectively. A protrusion having the same shape as that on the both surfaces symmetrically and provided with a movable electrode continuous on at least the surface thereof, and an insulating film provided on the contact surface of at least one of the stator and the movable member. Is configured.

[0005]

With the above-mentioned means, in the state where the mover is in contact with the inclined surface of the lower stator electrode through the insulating film, the lower stator electrode has a negative pole and the upper stator electrode has a positive pole. When a DC voltage is applied, the mover is negatively charged. Then, an electrostatic attraction force acts between the upper stator electrode and the electrode of the mover, the mover is attracted to the upper stator electrode, and contacts the inclined surface of the upper stator electrode. The vertical surface then attracts the mover to the right and eventually contacts the vertical surface of the upper stator electrode. There is conduction between the upper stator and the mover, and the mover is charged to the + pole. Next, a suction force acts between the lower stator and the mover, and the mover moves downward. When the mover contacts the inclined surface of the lower stator electrode, the vertical surface attracts the mover to the right and eventually contacts the vertical surface of the lower stator electrode. As a result, the mover moves right by the pitch λ. Further, conduction is established between the lower stator and the mover, and the mover is negatively charged. By repeating this operation, the mover moves to the right. In this way, the mover can be moved only by applying the DC voltage between the upper and lower stators, so that the driving device can be simplified and the actuator can be downsized.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side view showing the structure of a linear electrostatic actuator of the present invention. In the figure, 1 is the lower stator,
Reference numeral 11 is a saw-toothed protrusion, 12 is a stator electrode, 13 is an insulating film, and 14 is a photoconductor. Reference numeral 2 is an upper stator, 21 is a saw-toothed protrusion, 22 is a stator electrode, and 23 is an insulating film.
Reference numeral 3 is a mover, 31 is a saw-tooth projection having the same shape as the projections of the stators 1 and 2, 32 and 34 are mover electrodes, and 33 is a photoreceptor. The manufacturing process of this electrostatic actuator is shown in the side sectional views of FIGS. FIG. 4 is a partially enlarged sectional view thereof. (1) First, the lower stator 1 is manufactured. Photoreceptor 1 made of positive photosensitive polymer material (PMMA) on substrate 4
4 is spin-coated (rotational coating) (FIG. 2A). (2) The light-shielding mask 5 provided with a thin slit is brought close to the photoconductor 14 and is irradiated with the ultraviolet ray 6 while moving to the left side of the paper by one pitch λ (FIG. 2B). Since the exposure depth depends on the exposure time, the exposure becomes deeper to the right in one pitch. (3) When the exposed portion of the photoconductor 14 is removed by the developing solution, the photoconductor 14 has a sawtooth-shaped projection 1 having a downward slope.
1 is patterned (FIG. 2C). (4) Cr is deposited on the entire surface of the patterned photoreceptor 14 by vapor deposition or sputtering to form the stator electrode 12 (FIG. 4). The electrodes may be any conductive metal such as Cu or Ni. (5) The insulating film 13 is formed on the inclined surface by sputtering using SiO ₂ . The insulating film 13 may be made of Teflon having lubricity or may be formed by vapor deposition. (6) Phosphosilicate on the insulating film 13
A sacrificial layer 71 made of glass (PSG) is formed (FIGS. 2D and 4). (7) Next, the mover 3 is formed. For the mover 3, after forming a plating seed layer such as Cr on the sacrificial layer 71, Ni is deposited by electroplating, and the mover electrode 32 is formed.
Are formed (FIG. 3 (A)). The mover electrode 32 is not limited to Ni and may be any conductive metal. (8) The surface of the mover electrode 32 is flattened by electrolytic polishing or the like. (9) A PMMA photoconductor 33 is spin-coated on the planarized surface of the mover electrode 32. (10) The origin of the slit of the light-shielding mask 5 is positioned and the ultraviolet rays 6 are irradiated to form the saw-toothed protrusion 31 having an inclination opposite to the inclination of the lower electrode surface. (11) The exposed portion is removed with a developing solution. Photoconductor 33
Is patterned into a saw-toothed protrusion having an upward slope. (12) The stator electrode 22 and the mover electrode 32, which are formed by sputtering Cr on the entire surface of the photoreceptor 33, are electrically connected to the side surface of the mover 3. (13) A sacrifice layer 72 made of PGS is formed (see FIG. 2).
(B)). (14) Next, the upper stator 2 is manufactured. Only on inclined surfaces
The insulating film 23 is formed in the same manner as (5). (15) Form a Cr plating seed layer. (16) Ni is deposited by electroplating and the stator electrode 22
Are produced (FIG. 3C). (17) The sacrificial layers 71 and 72 are removed with an HF solution. (18) Finally, the lower stator 1 is displaced by λ / 2 with respect to the electrode pitch of the upper stator 2 to position and fix both stators. This completes the actuator (Fig. 3
(D)).

The driving state will be described with reference to FIG. Now
The DC power source 8 is wired so that the lower stator electrode 12 is the negative electrode and the upper stator electrode 22 is the positive electrode, and a voltage is applied. Since the mover electrode 32 is now in contact with the inclined surface 121 of the lower stator electrode 12, the mover 3 is negatively charged (a). After that, the upper stator electrode 22 and the mover electrode 3
An electrostatic attraction force acts between the moving parts 4 and
Be attracted to. After the mover electrode 34 contacts the inclined surface 221 of the upper stator electrode 22, an attractive force acts between the vertical surface 222 and the vertical surface of the mover 3, so that the mover 3 is attracted to the right side and eventually It contacts the vertical surface 222 of the upper stator electrode 22. The upper stator electrode 22 is electrically connected to the mover electrodes 32 and 34, and the mover 3 is charged to the + pole (b). Next, an attractive force acts between the lower stator electrode 12 and the mover 3, and the mover 3 moves downward. After the mover 3 contacts the inclined surface 121 of the lower stator electrode 12, the mover 3 is attracted to the right by the vertical surface 122 and eventually contacts the vertical surface 122 of the lower stator electrode 12. At this point, the mover 3 has moved one pitch (λ). By repeating this operation automatically, the mover 3 moves in zigzag between the upper and lower stators. In this way, the mover 3 can move only by applying the DC voltage between the upper and lower stators. If only the stator is positioned during manufacturing, this actuator does not require this positioning during assembly, which facilitates manufacturing. Moreover, since a complicated drive circuit is not required, the actuator can be downsized. Also, although not shown here,
According to the present invention, it is possible to obtain a rotary actuator by providing electrodes radially and attaching a shaft to the center of the moving element.

[0008]

As described above, according to the present invention, a stator having a serrated projection on one side thereof and a metal film disposed on the surface thereof is made to face each other with a certain gap, and the same portion is provided in the gap. Since the movable elements having saw-toothed surfaces on both sides are arranged, there is an effect of obtaining a small-sized actuator that does not require assembly alignment and does not require complicated wiring or a drive circuit.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a structure of an electrostatic actuator of the present invention.

FIG. 2 is a side sectional view showing a manufacturing process of the electrostatic actuator of the present invention.

FIG. 3 is a side sectional view showing a manufacturing process of the electrostatic actuator of the present invention.

FIG. 4 is a partially enlarged sectional view of the electrostatic actuator of the present invention.

FIG. 5 is a side sectional view showing a driving state of the electrostatic actuator of the present invention.

[Explanation of symbols]

 1: Lower stator 11: Protrusion 12: Stator electrode 121: Stator electrode inclined surface 122: Stator electrode vertical surface 13: Insulating film 14: Photoconductor 2: Upper stator 21: Protrusion 22: Stator electrode 221: Stator electrode inclined surface 222: Stator electrode vertical surface 23: Insulating film 3: Moving element 31: Protrusions 32, 34: Moving element electrode 33: Photoconductor 4: Substrate 5: Shading mask 6: Ultraviolet ray 7: Sacrificial layer 71: Sacrificial layer between lower stator and mover 72: Sacrificial layer between upper stator and mover 8: DC power supply

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junichi Ono 2-1, Kurosaki Shiroishi, Hachimansai-ku, Kitakyushu, Fukuoka Prefecture Yasukawa Electric Co., Ltd.

Claims (2)

[Claims] 1. Two stators having saw-toothed protrusions provided on one side with a pitch λ and having continuous stator electrodes on at least the surface thereof are opposed to each other with a gap, and
A pair of stators which are displaced by a pitch λ / 2 in the moving direction, and projections having the same shape as the stator are provided symmetrically on both surfaces, the projections being provided in the gaps between the stator pairs and facing the two stators. An electrostatic actuator comprising: a movable element having a continuous movable element electrode on at least its surface, and an insulating film provided on a contact surface of at least one of the stator and the movable element. 2. The stator and the protrusion of the mover have one side of the protrusion perpendicular to the moving direction and the other side of the protrusion having an inclined surface with respect to the moving direction, which is the contact surface. 1. The electrostatic actuator according to 1.