JPH11136961A - Electrostatic wobble motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic wobble motor with large rotation and retention torque. SOLUTION: A stator electrode 15a that is one electrode operated by electrostatic force is arranged on the surface of a conical surface which is provided on the upper surface of a stator 22, and a rotor is subjected to precession, while the lower surface of a rotor 23 with a rotor electrode 17 that is the other electrode and the stator electrode 15a are being continuously subjected to line contact via an insulating film 21. As a result, according to the line contact state between the rotor electrode 17 and the stator electrode 15a, the distance between the both electrodes is minimized, the effective area of electrostatic connection is maximized, and at the same time sliding friction resistance is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic wobble motor used as a small actuator expected to be used in electronic equipment and the like in the future.

[0002]

2. Description of the Related Art An electrostatic wobble motor is a motor that rotates by using an electrostatic attraction between a rotor and a stator. Although it has a simple structure, it has a built-in deceleration mechanism and can expect a high rotation torque. It is promising as a microactuator because it is advantageous for miniaturization.

FIG. 4 is a sectional view showing the structure of a conventional planar electrostatic wobble motor.

[0004] L. Paratte, H .; Lorenz,
R. Luthier, R .; Clavell and N.M.
F. de Rooij "Miniature Gea
rReduction Unit Drive by
a Silicon Electrostatic
Wobble Motor ", Proc. IEEMic
ro Electro Mechanical Sys
tems, pp. 119-123, 1994. As disclosed in Japanese Patent Application Laid-Open No. H11-260, a conventional planar electrostatic wobble motor has a disk-shaped rotor electrode 17 and a rotating shaft
, A disk-shaped rotor 23 having:
A stator 22 having a ground electrode 13 disposed at the center of the upper surface of the upper surface and a plurality of stator electrodes 15 radially disposed around the ground electrode 13 and equally divided in an arc shape, and an electric connection between the rotor electrode 17 and the stator electrode 15. An insulating layer 21 as means for preventing a short circuit, wherein a voltage sequentially applied to the stator electrode 15, a ground voltage applied to the rotor electrode 17 via the ground electrode 13 and the rotating shaft 19, and Between the rotor 23 and the stator electrode 15 on the upper surface of the stator 22.
It is configured to perform a precession in synchronization with the drive of.

[0005] The rotor electrode 17 constituting the rotor 23
The rotating shaft 19 is electrically connected to the rotating shaft 19 by a connecting portion 26. Further, the connecting portion 26 has a structure having rigidity in the rotation direction and elasticity with respect to the inclination of the rotor electrode 17.

That is, when a voltage is sequentially applied between the rotor electrode 17 and the stator electrode 15, an electrostatic force is generated, and the rotor electrode 17 is sequentially attracted to the stator electrode 15. Therefore, when the stator electrode 15 to which the voltage is applied is continuously switched, the rotor 23 is rotated around the imaginary rotation center line 20.
Roll while revolving on top of 5.

The difference between the length of the outer periphery of the rotor 23 and the length of the orbit of the rotor 23 on the stator electrode 15 causes the rotor 23 to rotate.

[0008]

Generally, the electrostatic force F acting between two opposing planes is described in "Yada, Sakata, Hosoya: Development of Wobble Motor, Transactions of the Japan Society of Mechanical Engineers (C edition), 58
Vol. 549 (1992-5), 1628-1633 ", the dielectric constant is ε, the drive voltage is V, the distance between the electrodes (the distance between the rotor and the stator) is d, and the electrode area is A. Then, it is expressed by the following equation. F = (1/2) × ε (V ² / d ² ) × A

It can be seen that if the drive voltage V is fixed, the electrostatic force F can be increased by reducing the distance d between the electrodes as much as possible and increasing the electrode area A as much as possible.

However, in the conventional electrostatic wobble motor, a disk-shaped rotor 23 that precesses like a top on the upper surface of a flat substrate is provided with a stator electrode 15 provided on the upper surface of the substrate at the outer periphery. It is configured so as to make point contact. Therefore, the stator electrode 15 and the rotor electrode 17
The effective value of the electrostatic coupling area with the substrate is extremely small, and the electrostatic force acting therebetween is also small. That is, even if the electrode area A is increased, the distance d between the electrodes is increased, the electrode area A does not work effectively, and the electrostatic attraction does not increase. For this reason, there is a major problem that the rotation torque of the motor is small and cannot be put to practical use.

Accordingly, an object of the present invention is to provide an electrostatic wobble motor having a large rotating torque in low-voltage driving by increasing the rotating torque and holding torque in the electrostatic wobble motor.

[0012]

To achieve the above object, an electrostatic wobble motor according to the present invention is provided with a convex conical surface on a part of the upper surface of a substrate constituting a stator, and the surface of the conical surface is provided. The arrangement is such that the rotor precesses in a state where the lower surface of the rotor electrode and the stator electrode are always in linear contact with each other via the insulating layer.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the plan view of FIG. 1 and the sectional views of FIGS.

As shown in FIGS. 1 and 2, the electrostatic wobble motor according to the present embodiment includes a disk-shaped rotor electrode 17 having the same configuration as a conventional rotor, and a rotating shaft 19 penetrating the center thereof. A disk-shaped rotor 23,
A substrate and a ground electrode 1 arranged at the center of the upper surface of the substrate
3, a stator 22a including a conical surface 27 having a convex shape on the periphery thereof, and a stator electrode 15a radially arranged on the surface of the conical surface 27 and divided into 12 arc-shaped portions, and the rotor electrode 23 and the stator electrode 15a. And an insulating layer 21 as means for preventing an electrical short circuit.

Further, the electrostatic force acting between the voltage sequentially applied to the stator electrode 15a and the ground voltage applied to the rotor electrode 17 via the ground electrode 13 and the rotating shaft 19, The rotor 23 precesses on the upper surface of the stator 22a in synchronism with the driving of the stator electrode 15a in a state where the lower surface of the rotor electrode 17 and the stator electrode are always in line contact with each other via the insulating layer. Have been.

That is, when a voltage is sequentially applied between the rotor electrode 17 and the stator electrode 15a,
Electrostatic force is generated, and the rotor electrode 17 is connected to the stator electrode 15a.
Are sequentially attracted to the electrodes. At this time, since the stator electrode 15a is formed on the surface of the conical surface 27, the lower surface of the rotor electrode 17 and the stator electrode are in line contact with each other via the insulating layer. Therefore, when the stator electrode 15a to which voltage is applied is continuously switched,
The rotor 23 precesses on the stator electrode 15 about the imaginary rotation center line 20a. Roll while revolving.

Next, a method for manufacturing the stator 22a will be described. The substrate 11 is manufactured by an injection molding method using an epoxy resin as a material. At this time, a convex conical surface 27 having a base angle of a predetermined conical surface is simultaneously formed on a part of the upper surface of the substrate 11. Furthermore, the ground electrode 13 and the stator electrode 15a were formed on the surface of the conical surface 27 by vacuum-depositing Ni and Au using a predetermined metal mask.

The rotor electrode 17 has a thickness of 0.1 m.
An aluminum plate was formed by etching an Al plate having a thickness of m using a wet etching method, and the insulating layer 21 was an aluminum oxide layer formed by anodizing the rotor electrode 17 in a sulfuric acid aqueous solution.

The rotor electrode 17 in the electrostatic wobble motor manufactured in this embodiment is electrically connected to the ground electrode 13 through the rotating shaft 19 and the ground electrode 13. Each of the 12 radially divided stator electrodes 15a is sequentially connected to a positive or negative power supply.

A voltage is sequentially applied to each of the radially divided stator electrodes 15a, and the rotor electrode 17 and the individual stator electrodes 15a are sequentially attracted by electrostatic force to cause the rotor 23 to precess.

In this embodiment, the rotor electrode 17 is provided by providing the stator electrode 15a on the surface of the conical surface 27.
And the stator electrode 15a are almost in line contact with each other via the insulating layer 21, and the rotational torque is improved as compared with the related art.

In the electrostatic wobble motor manufactured in this embodiment, the base angle θ of the conical surface 27 shown in FIG.
゜, the thickness of the insulating layer 21 is 0.005 mm, the electrode length L is 1 mm, and the average distance of the gap formed between the insulating layer 21 and the stator electrode 15a when the rotor 23 and the stator electrode 15a are in contact with each other is It was 0.01 mm. As a result, about six times the electrostatic attraction was obtained as compared with the related art.

As shown in FIG. 2, according to the embodiment of the present invention, since the rotor electrode 17 and the stator electrode 15a are in line contact with each other via the insulating layer 21,
By forming the stator electrode 15a just below the ground electrode 13, the electrostatic force is further increased by the increased area of the stator electrode 15a.

As the electrostatic force between the rotor electrode 17 and the stator electrode 15a increases, the influence on external impacts and the like also decreases, and stable driving can be obtained.

In the embodiment of the present invention, the insulating layer 21
Although the description has been given using the structure formed on the surface of the rotor electrode 17, it may be formed on either the surface of the rotor electrode 17 or the surface of the stator electrode 15a.

In the embodiment of the present invention, the conical surface 2
7, the structure in which the stator electrode 15a is provided on the surface has been described as an example.
a itself may be formed on a convex conical surface.

[0027]

According to the present invention, by providing the stator electrode on the surface of the conical surface, the rotor electrode and the stator electrode come into substantially line contact with each other via the insulating layer, and the stator electrode is grounded. Since it can be formed to the very edge of the electrode, the electrode area due to electrostatic force is increased, and
Since the distance between the rotor electrode and the stator electrode can be reduced, a large increase in rotational torque and holding torque can be expected.

[Brief description of the drawings]

FIG. 1 is a plan view showing a structure of an electrostatic wobble motor according to an embodiment of the present invention.

FIG. 2 is a sectional view showing the structure of the electrostatic wobble motor according to the embodiment of the present invention.

FIG. 3 is a sectional view showing a stator structure of the electrostatic wobble motor according to the embodiment of the present invention.

FIG. 4 is a sectional view showing the structure of a conventional electrostatic wobble motor.

[Explanation of symbols]

 θ Base angle of conical surface 11 Substrate 13 Ground electrode 15, 15a Stator electrode 17 Rotor electrode 19 Rotation axis 20, 20a Virtual rotation center line 21 Insulating layer 22, 22a Stator 23 Rotor 26 Connection 27 Conical surface

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigeyuki Takahashi 840 Takeno Shimotomi, Tokorozawa-shi, Saitama Citizen Watch Co., Ltd. 840 Citizen Watch Co., Ltd.

Claims (1)

[Claims] 1. A disk-shaped rotor having a disk-shaped rotor electrode and a rotating shaft penetrating at the center thereof, a ground electrode disposed at the center, and radially disposed around the ground electrode and equally divided into an arc shape. A stator composed of a substrate having a large number of stator electrodes on its upper surface, and an insulating layer as a means for preventing an electrical short circuit between the rotor electrodes and the stator electrodes, and a voltage sequentially applied to the stator electrodes. The rotor is precessed on the upper surface of the stator in synchronization with the driving of the stator electrode by an electrostatic force acting between the ground electrode and a ground voltage applied to the rotor electrode via the rotating shaft. In the electrostatic wobble motor, a convex conical surface is provided on a part of the upper surface of the substrate, and the stator electrode is disposed on the surface of the conical surface. More, electrostatic wobble motor, characterized in that the lower surface of said rotor and said stator electrode is the said rotor in a state in which through the insulating layer in contact always line is configured to precess.