JPH04368479A - Electrostatic actuator - Google Patents

Abstract

PURPOSE:To provide an electrostatic actuator which can displace a movable unit even in a direction perpendicular to its plane by utilizing an electrostatic force and an elastic force of a beam. CONSTITUTION:A beam 8 is secured at one end to a board 7, a movable electrode 9 having pectinated teeth 9a, 9b is supported to the other end side of the beam 8, and at least two stationary electrodes 10, 11a, 11b are arranged on the lower surface side of the electrode 9 in the extended direction of the teeth 9a, 9b. Movable electrode control means for controlling to so move the electrode 9 as to be excited by electrostatic forces of the electrodes 10, 11a, 11b and an elastic force of the beam 8, is provided.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic actuator used in paper feeding mechanisms and the like.

0002

2. Description of the Related Art An example of a conventional electrostatic actuator will be described with reference to FIG. A movable part 3 having comb-like movable electrodes 2 on the left and right sides is provided on the Si substrate 1, and this movable part 3 is supported by a beam 4 formed at the center of the movable part 3. It is fixed by a fixing part 5 of the substrate 1. As a result, the movable electrode 2 and the beam 4 are floating above the Si substrate 1. Furthermore, fixed electrodes 6 having comb-like tips are disposed on both sides of the movable electrode 2, and the comb-teeth at the tips of the fixed electrode 6 and the movable electrode 2 mesh with each other. There is.

In such a configuration, when an alternating current voltage is applied between the fixed electrode 6 and the movable electrode 2 arranged on both sides, an electrostatic force acts between them, and as a result, the movable electrode 2 of the movable part 3 is combed. It vibrates as it is pulled in and pushed out between the teeth. However, no displacement mechanism has been proposed for extracting the vibrations to the outside.

0004

[Problems to be Solved by the Invention] As mentioned above, the development of microactuators using Si microfabrication technology is actively underway, but it is difficult to provide a part that transmits displacement and actually function as an actuator. There are no examples of such cases.

[0005]

[Means for Solving the Problem] In the invention according to claim 1, one end of the beam is fixed to the substrate, a movable electrode part is supported on the other end side of the beam, and the lower surface side of the movable electrode part and the same plane At least two fixed electrode parts facing each other are arranged at the top, and a movable electrode control means is provided for controlling the movement of the movable electrode part so that it moves by an electrostatic force with the fixed electrode part and a spring force with the beam. Ta.

According to the second aspect of the invention, in the first aspect of the invention, an umbrella-shaped cover member is attached to the upper part of the movable electrode section.

According to the third aspect of the invention, in the first aspect of the invention, an elastic film is attached to the upper part of the movable electrode section.

[0008]

[Operation] In the invention as claimed in claim 1, by controlling the driving force between the movable electrode part and the fixed electrode part using the movable electrode control means, the electrostatic force generated between the movable electrode part and the fixed electrode part can be reduced. Due to the spring force generated between the movable electrode section and the beam, it becomes possible to move the movable electrode section not only in a direction parallel to the substrate but also in a direction perpendicular to the substrate.

In the invention as claimed in claim 2, by attaching the umbrella-shaped cover member to the upper part of the movable electrode section, when the present device is used as a paper feeding mechanism, dust such as paper etc. is not collected as in the conventional case. It is possible to reduce the possibility that the actuator will not operate properly due to falling into the groove between the movable electrode part and the fixed electrode part.

In the third aspect of the invention, by attaching an elastic film to the upper part of the movable electrode part, it is possible to further enhance the effect of removing dust, thereby further preventing the actuator from operating normally. It is possible to reduce this.

[0011]

[Embodiment] A first embodiment of the present invention will be explained based on FIGS. 1 to 7. One ends of two beams 8 are fixed on the substrate 7 in the vertical direction (Y direction), and a movable electrode section 9 is supported on the other end side of these two beams 8. The movable electrode portion 9 has comb teeth 9a and 9b in the left and right direction (X direction), respectively.
is formed. Furthermore, fixed electrode sections 10, 11a, and 11b are provided on the lower surface side of the movable electrode section 9 and in the X direction in which the comb teeth 9a and 9b extend, respectively. The distal ends of the fixed electrode portions 11a and 11b are formed into a comb shape that engages with the comb teeth 9a and 9b. Furthermore, here, an electrostatic force acts between the movable electrode part 9 and the fixed electrode parts 10, 11a, 11b, and a spring force acts between the movable electrode part 9 and the beam 8. As shown, movable electrode control means (not shown) is provided.

With this configuration, the manufacturing process of this device will be explained based on FIGS. 2 and 3. In addition, Figure 2
Since (a) to (d) correspond to FIGS. 3(a) to (d), respectively, the explanation will be given below simply by referring to (a) to (
d).

First, on the Si substrate 12, SiO2 1
3 and Si3N414 are laminated with a thickness of 0.2 μm each (the Si substrate 12, SiO2 13, and Si3N414 constitute the substrate 7). That S
Al is deposited to a thickness of 0.2 μm on the i3N414 and etched to form the electrode 15 (a). Next, SiO2 16 is deposited to a thickness of 1 μm and etched to form a portion of the movable electrode portion 9 excluding the comb teeth 9a and 9b and a portion located below the beam 8 portion (b
). Next, about 2 μm of poly-Si 17 is deposited over the entire surface of the SiO2 layer 16 (c). Then that pol
The y-Si 17 is etched to form the movable electrode section 9, the fixed electrode sections 11a and 11b, the beam 8, etc. (d). Finally, the SiO2 16 serving as the sacrificial layer is removed using BHF (buffered hydrofluoric acid), thereby separating the movable electrode part 9 located in the center from the fixed electrode part 10 located below and leaving it floating in the air. do. In this way, it becomes possible to manufacture the electrostatic actuator having the configuration shown in FIG. 1(b) as described above.

[0014] Then, the electrostatic actuator manufactured in this way is controlled by the movable electrode 9 using the movable electrode control means.
By sequentially applying a voltage between the movable electrode part 9 and the fixed electrode part 10 below it, and between the movable electrode part 9 and the left and right comb teeth thereof, Since an electrostatic force can be applied between the fixed electrode parts 11a and 11b extending from the movable electrode parts 9a and 9b, and a spring force can also be applied between the movable electrode part 9 and the beam 8, the movable It becomes possible to move the electrode 9 in the vertical direction (direction perpendicular to the XY plane) and in the horizontal direction (X direction). By placing a piece of paper on the object, you can move the object to the left (or right).

Next, the basic operating principle of the electrostatic actuator will be explained based on FIGS. 4 to 7. Figure 4 is Figure 1
FIG. 5 shows a side view of the basic structure in a state where a voltage V forming part of the movable electrode control means is applied. Therefore, now, Fig. 6(a) to (e)
) We will explain the basic operation based on the following. First, (a) shows a state before operation, in which an object 18 is placed on the upper part of the movable electrode section 9. Next, as shown in (b), when a voltage V is applied between the movable electrode part 9 and the fixed electrode part 11a on the left side, the movable electrode part 9 is drawn toward the fixed electrode part 11a by electrostatic force. As a result, the object 18 placed on the movable electrode section 9 also moves toward the fixed electrode section 11a. Next, as shown in (c), the movable electrode part 9
When a voltage V is also applied between the movable electrode part 9 and the lower fixed electrode part 10, the movable electrode part 9 is also attracted to the lower fixed electrode part 10, so the object 18 is separated from the movable electrode part 9 and supported. It is placed on the upper part of the fixed electrode parts 11a and 11b which serve as a stand. Next, as shown in (d), when the voltage between the movable electrode section 9 and the fixed electrode section 11a is cut off, the movable electrode section 9 returns to the right due to the tension force of the beam 8. Next, as shown in (e), when a voltage is applied between the movable electrode section 9 and the fixed electrode section 10, the movable electrode section 9 returns to its original position due to the tension force of the beam 8. By repeating the operations (a) to (e) as described above, the object 18 can be carried to the left. Figure 7
(a) shows the voltage waveform when carrying the object 18 to the left, waveform A shows the voltage waveform applied to the fixed electrode part 11a, and waveform B shows the voltage waveform applied to the fixed electrode part 10. It shows. Further, as shown in FIG. 7(b), by applying a voltage of waveform C to the fixed electrode part 11b and a voltage of waveform D to the fixed electrode part 10, the object 18
It is also possible to carry it to the right.

Next, a second embodiment of the present invention will be explained based on FIG. Note that a description of the same parts as in the first embodiment described above will be omitted, and the same parts will be denoted by the same reference numerals. Here, a cover plate 19 as a cover member is attached to the upper part of the movable electrode part 9 constituting the electrostatic actuator so as to cover the entire actuator part. To manufacture this cover plate 19, after the steps shown in FIGS. 2(c) and 3(c) described above, SiO2 (not shown) is deposited over the entire surface, and SiO2 located on the upper part of the movable electrode part 9 is It can be produced by etching and removing, and then sequentially depositing Si3N419a and poly-Si19b.

By forming the cover plate 19 on the upper part of the movable electrode portion 9 in this manner, it is possible to carry paper or the like that easily generates dust as the object 18 when the cover plate 19 is not provided as in the conventional case. When the groove 20 between the movable electrode section 9 and the fixed electrode section 11a (particularly the comb teeth 9a)
, 9b) is clogged with dust and the comb teeth 9a, 9b cannot operate normally. Therefore, the cover plate 19
By newly providing the groove 20, it is possible to reduce the amount of dust that falls into the groove 20, and to perform the normal transportation operation for a long time.

Next, a third embodiment of the present invention will be explained based on FIG. Here, instead of providing the cover plate 19 on the upper part of the movable electrode section 9 as in the second embodiment described above,
An elastic film 21 is pasted over the entire surface. As the material of the elastic film 21, polyethylene, soft polyvinyl chloride, polyurethane, etc. can be used. By covering the entire surface of the actuator section with the elastic film 21 in this way, dust is prevented from entering the groove 20, so that the object 18, such as paper, which tends to generate dust, can be placed on it and moved. Even if it does, it is possible to perform good drive control over a long period of time.

[0019]

[Effects of the Invention] According to the invention described in claim 1, one end of a beam is fixed to a substrate, a movable electrode part is supported on the other end side of the beam, and the movable electrode part is opposed to each other on the lower surface side and on the same plane. At least two fixed electrode parts are disposed, and a movable electrode control means is provided for controlling the movement of the movable electrode part so that it moves by the electrostatic force with the fixed electrode part and the tension force with the beam. By controlling the driving force between the movable electrode part and the fixed electrode part using a movable electrode control means, the electrostatic force generated between the fixed electrode part and the spring force generated between the beam can be reduced. Accordingly, the movable electrode portion can be moved not only in a direction parallel to the substrate but also in a direction perpendicular to the substrate.

In the invention as claimed in claim 2, since the umbrella-shaped cover member is attached to the upper part of the movable electrode part, when this device is used as a paper feeding mechanism, dust such as paper etc. This reduces the possibility of the actuator falling into the groove between the fixed electrode section and the fixed electrode section and causing the actuator to malfunction, thereby making it possible to perform stable drive control at all times.

[0021] According to the third aspect of the invention, since an elastic film is attached to the upper part of the movable electrode part, it is possible to further enhance the effect of removing dust, thereby further reducing the possibility that the actuator does not operate normally. , it becomes possible to perform even more stable drive control.

[Brief explanation of the drawing]

FIG. 1 shows a first embodiment of the present invention, (a
) is a plan view of the electrostatic actuator, (b) is its a-a
FIG.

FIG. 2 is a process diagram showing the manufacturing process of the first example as seen from a planar state.

FIG. 3 is a process diagram showing the manufacturing process of the first example when viewed from a cross-sectional state.

FIG. 4 is a plan view illustrating the basic operation of the actuator section in the first embodiment.

FIG. 5 is a side view showing a state in which a circuit for applying voltage is connected to the basic configuration of FIG. 4;

FIG. 6 is an operation explanatory diagram showing the basic operation principle when moving an object to the left.

[Figure 7] (a) is a waveform diagram showing the voltage waveform applied to the electrode when carrying an object to the left, and (b) is a waveform diagram showing the voltage waveform applied to the electrode when carrying the object to the right. FIG.

FIG. 8 shows a second embodiment of the present invention, (a
) is a plan view of the electrostatic actuator, and (b) is a cross-sectional view thereof.

FIG. 9 shows a third embodiment of the present invention, (a
) is a plan view of the electrostatic actuator, and (b) is a cross-sectional view thereof.

FIG. 10 is a plan view showing an example of a conventional electrostatic actuator.

[Explanation of symbols]

7 Board 8
Beam 9
Movable electrode part 10,1
1a, 11b Fixed electrode part

Claims (3)

[Claims] 1. A beam having one end fixed to a substrate, a movable electrode portion supported by the beam, and at least two fixed electrode portions facing each other on the lower surface side of the movable electrode portion and on the same plane.
An electrostatic actuator characterized in that a movable electrode control means is provided for controlling the movement of the movable electrode part so that the movable electrode part moves by an electrostatic force with the fixed electrode part and a spring force with the beam. 2. The electrostatic actuator according to claim 1, further comprising an umbrella-shaped cover member attached to the upper part of the movable electrode section. 3. The electrostatic actuator according to claim 1, further comprising an elastic film attached to the upper part of the movable electrode section.