JPH07213077A - Light control type electrostatic drive actuator - Google Patents

Abstract

(57) [Abstract] [Purpose] A driving force can be obtained with a relatively simple structure of only irradiation of light or a combination of light and an electrostatic field, and the movement of the electrostatically driven actuator can be controlled by controlling the light. An object of the present invention is to provide a light control type electrostatic drive actuator that can be easily controlled one-dimensionally or two-dimensionally. A light control type in which a movable element is moved by electrostatic interaction between a periodic charge distribution generated in a movable element by light irradiation from a light source and a periodic charge distribution of a stator facing the movable element. In the electrostatic drive actuator, a light control type electrostatic drive actuator, characterized in that at least the movable element is made of a photovoltaic crystal material that is irradiated with light to generate an electric current.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to actuators for driving minute parts such as micromachines, for example, electric and optical equipments requiring electrical or optical switches, medical equipments requiring remote operation, robot fields, etc. The present invention relates to a light control type electrostatic drive actuator driven by an electric field and light.

[0002]

2. Description of the Related Art Various actuators utilizing electrostatic force have been proposed so far. For example NIKKEI MECHANICA
L Page 43 1989.3.20 and PROCEEDINGS IEEE CATALOG NUMBE
R 91CH2957-9 (1991) 9 pages etc. FIG. 7 shows an outline of a rotary type electrostatic actuator.

In FIG. 7, twelve stator electrodes 11 are circularly arranged on a substrate 10 to form a stator electrode group. The mover 12 is arranged inside the stator electrode group. Rotor electrodes 13 facing the stator electrodes 11 are formed on the four protrusions of the mover 12. The twelve stator electrodes 11 are divided into four types of groups, and voltages are applied with different phases (Φ ₁ , Φ ₂ , Φ ₃ ). When a voltage is applied to the stator electrodes 11 of one group, an electrostatic attractive force acts between the stator electrodes 11 and the rotor electrodes 13, and a couple is generated in the mover 12 to start rotation. By sequentially switching the groups of the stator electrodes 11 to which a voltage is applied, the mover 12 continuously rotates.

[0004]

However, in the case of the conventional electrostatically driven actuator as described above, since the continuous motion is realized by switching the voltage applied to the stator electrode 11, the voltage is applied to the stator electrode 11. It is necessary to form an electric circuit to provide the same, and further, it is necessary to form a bearing for the mover 12. This becomes a difficult task as the actuator element becomes smaller, and there is a drawback that the lower limit of the size of the actuator element that can be realized depends on the processing accuracy. Further, in this case, a possible motion is a rotary motion, and there is a drawback that only one motion of freedom is realized.

The present invention has been made to solve the above-mentioned drawbacks of the conventional electrostatic drive actuator.
The purpose is to obtain a driving force with a relatively simple structure of only irradiation of light or a combination of light and an electrostatic field. Also, by controlling light, the movement of the electrostatically driven actuator can be controlled in one or two dimensions. SUMMARY OF THE INVENTION It is an object of the present invention to provide a light control type electrostatic drive actuator which can be easily controlled.

[0006]

In order to achieve the above object, the present invention uses a photovoltaic crystal material as a mover, and the mover is derived from the density of interference fringes of light by coherent two-beam irradiation. The driving force is obtained by the electrostatic interaction between the charge distribution inside and the electric field of the stator. Here, when an electrode is formed in advance as the stator, one-dimensional movement is performed, while when a photovoltaic crystal material is used as the stator, two-dimensional movement is possible. FIG. 1 shows the configuration of the present invention in the case of using a photovoltaic crystal material for both the mover and the stator.

The mover 21 is arranged on the stator 22, and the directions 23 and 24, which are peculiar to the material in which the current flows in the respective photovoltaic crystals, are opposite to each other. The movable elements 21 are irradiated with coherent light beams 25 and 26 so as to strike the movable elements 21 to form interference fringes of light in the movable element 21. At the same time, the light transmitted through the mover 21 is also configured to form light interference fringes in the stator 22.

FIG. 3 shows a structure in which a photovoltaic crystal material is formed on the mover 44, and stripe electrodes are formed on the stator 41. That is, the stator 41
Comb-shaped electrodes 42 and 43 are formed on top of each other, different voltages are applied to each, and a mover 44 made of a photovoltaic crystal material is placed on the comb-shaped electrodes 42 and 43 to emit light.

[0009]

FIG. 2 is a view for explaining the constitution in the case where the photovoltaic crystal material is used for both the mover 21 and the stator 22 of FIG. 1, and shows the moving principle of the mover. . In FIG. 2, interference fringes of light are formed in both the mover 31 and the stator 32, and the portions 33, 3 with high light intensity are formed.
5 and weak light intensity portions 34 and 36 are formed. Now, in the photovoltaic crystal material, the direction of current flow when irradiated with light is determined by the orientation of the photovoltaic crystal, and the current density is proportional to the light intensity. Therefore, charge distribution occurs in the photovoltaic crystal at the portions 33 and 35 where the light intensity is high, but the mover 3
Since the direction of the photovoltaic crystal, that is, the direction of the current is reversed between 1 and the stator 32, the same kind of electric charge is generated at the interface between the mover 31 and the stator 32. Therefore, both repel electrostatically.

Here, when the light interference fringes are oblique as shown in FIG. 2, the charge generation positions are deviated between the stator 32 and the mover 31, and the force on the mover 31 is the vector 37. Occurs in the direction of. When this is decomposed into a vector 39 and a vector 38, the vector 38 represents the component of the force that moves the mover 31, and indicates the moving direction of the mover 31. To change the moving direction of the mover 31, the incident angle or direction of light may be changed to change the direction of the interference fringes. Therefore, the mover 31 can freely move two-dimensionally on the stator 32. When the mover 31 moves, the positions of the charge distribution and the interference fringes are displaced, but the light distribution tries to rearrange the charge distribution as shown in FIG.
Even if the light irradiation is spatially fixed, the mover 31
As long as it is illuminated by the light, the mover 31 continues to move.

FIG. 4 shows a structure in which a photovoltaic crystal material is used as the mover 44 and the comb-shaped electrodes 42 and 43 are used as the stator 41 in FIG.
4 shows the movement principle of No. 4. On the stator 51,
Comb-shaped electrodes 52 and 53 having different polarities are alternately arranged to form a periodic electric field on the stator 51. On the other hand, the crystal orientation of the mover 54 made of photovoltaic crystal flakes, that is, the photocurrent flowing direction 57 is in the plane of the stator and is orthogonal to the comb electrodes 52 and 53. The interference fringes generated by the coherent lights 55 and 56 irradiating the mover 54 are parallel to the comb electrodes 52 and 53, and the pitch is a double period of the comb electrode pair. As shown in FIG. 4, the irradiation of light causes a bias in the electric charge in the portion where the light intensity is high.
Here, by shifting the phase of the interference fringes and the phases of the comb-shaped electrodes 52, 53, electrostatic repulsive force is generated in the shifted direction to move the mover 54. In this case, the mover 54 moves only in the direction perpendicular to the comb electrodes 52 and 53, and has a one-dimensional degree of freedom.

[0012]

【Example】

Example. 1 FIG. 5 shows a first embodiment of the present invention. Both the mover 63 and the stator 62 are made of strontium / barium niobate (Sr0.6B) which is a photovoltaic crystal material.
a0.4 Nb ₂ O ₆ : hereinafter referred to as SBN) is used. The usage environment is room temperature (about 20 ° C.). 1 as the stator 62
A SBN single crystal of 0 mm × 10 mm × 3 mm is used,
Here, the direction of current flow is along the side of 3 mm (the C-axis direction of the crystal), and one surface of 10 mm × 10 mm is optically polished.

On the other hand, as the mover 63, the same SBN is used.
Single crystal 1 mm x 1 mm x 0.05 mm flakes are used. Here, the direction of current flow is along the side of 0.05 mm. Also here, one surface of 1 mm × 1 mm is optically polished. Next, both the mover 63 and the stator 62 are heated to 100 ° C. by applying a positive voltage to the surface that is optically polished and applying a positive voltage to the opposite surface so that an electric field of 4 KV / cm is obtained. After that, with the voltage still applied, the temperature is gradually cooled to room temperature over about 1 hour, and finally the voltage is reduced. The above is the stator 62 and the mover 6.
Preparation for 3.

Next, the stator 62 and the movable member 63 are adhered to each other so that the optical polishing surfaces of the movable member 63 and the movable member 6 face downward.
3 is placed on the top, and the whole is immersed in matching oil 61 having a refractive index of 1.5. This is to minimize the reflection of light on the SBN crystal surface.

The irradiation light has a wavelength of 488 nm and an intensity of 20.
A laser beam 64 of W / cm ² is divided into two laser beams 66 and 67 having a minute angle difference through a glass plate 65 having a wedge. Here, the interval of the interference fringes is about 50 μm. The glass plate 65
Has a surface flatness of 20 nm or less and has a rotation mechanism, and can change the direction of interference fringes.

Under this condition, light irradiation for about 0.1 seconds accumulates electric charges sufficient to overcome gravity and starts moving. It moved at a speed of about 0.2 mm per second. By rotating the glass plate 65 having a wedge and changing the direction of the interference fringes, it was confirmed that the mover 63 moves on the stator 62 in any of front, rear, left and right directions.

Example. 2 FIG. 6 shows a second embodiment of the present invention. A stator 71 having comb-shaped electrodes 72 and 73 formed thereon is used, and a movable element 74 is made of KNbO ₃ single crystal thin piece (2 mm × 2 mm) which is a photovoltaic crystal material.
An example using x 0.1 mm) is shown. Here, the c-axis of the crystal (direction of current flow) is a direction along a side of 2 mm,
It is oriented in a direction perpendicular to the comb electrodes 72, 73. Here, the KNbO ₃ single crystal thin piece is obtained by optically polishing one surface of 2 mm × 2 mm and poling it in advance by applying a voltage of 5 KV / cm in the c-axis direction. It is arranged so as to be in contact with the electrodes 72, 73.

Here, the comb-shaped electrodes 72 and 73 are formed every 25 μm, and the comb-shaped electrode 72 has +20 V and the comb-shaped electrode 7 is formed.
A voltage of −20 V is applied to 3. The light irradiating the mover 74 is a laser beam 78 having a wavelength of 488 nm and an intensity of 20 W / cm ² through a glass plate 77 having a wedge,
The laser beam is divided into two laser beams 75 and 76 having a minute angle difference, and the interval of interference fringes is 100 μm. The interference fringes are parallel to the comb-shaped electrodes 72 and 73, and the phase thereof is found by moving the glass plate 77 in a direction perpendicular to the comb-shaped electrodes 72 and 73 under the condition that the mover 74 is most likely to move. Under this condition, the mover 74 starts to move about 5 milliseconds after light irradiation and moves at a speed of 2.5 mm per second. At this time, it was confirmed that the mover 74 moved in the direction in which the comb electrodes 72 and 73 were alternately straddled.

[0019]

As described above, the light control type electrostatic drive actuator of the present invention uses only the light or the light by using the photovoltaic crystal material for both the mover and the stator or for the mover. It was possible to move the mover with a relatively simple configuration, which was a combination of electrostatic fields. Also, when both the mover and the mover were made of photovoltaic crystal material, two-dimensional movement was possible.

[Brief description of drawings]

FIG. 1 is a diagram showing a structural example of the present invention in which a photovoltaic crystal material is used for both a mover and a stator.

FIG. 2 is a diagram for explaining the principle of movement of the mover in one configuration example of the present invention in which a photovoltaic crystal material is used for both the mover and the stator.

FIG. 3 is a diagram showing another configuration example of the present invention in which a stripe-shaped electrode is formed on the stator.

FIG. 4 is a diagram for explaining a moving principle of a mover in another configuration example of the present invention in which a stripe-shaped electrode is formed on a stator.

FIG. 5 is a diagram for explaining the configuration of the first embodiment of the present invention.

FIG. 6 is a diagram for explaining the configuration of the second embodiment of the present invention.

FIG. 7 is a diagram schematically showing a conventional electrostatic drive actuator.

[Explanation of symbols]

10 substrate 11 stator electrode 12 mover 13 rotor electrode 21 mover 22 stator 23 direction of current flow in the stator 24 direction of current flow in the mover 25, 26 coherent light 31 mover 32 stator 33 High light intensity part in the mover 34 Low light intensity part in the mover 35 High light intensity part in the stator 36 Low light intensity part in the stator 37 Vector direction of force generated in mover 38 Vector direction of force for moving the mover 39 Vector direction of force for moving the mover away from the stator 41 Stator 42,43 Comb electrode 44 Mover 51 Stator 52,53 Comb electrode 54 Mover 55,56 Yes Interfering light 57 Direction of photocurrent flow 58 High light intensity part in mover 59 Low light intensity part in mover 61 Matching oil 62 Stator 63 Movable element 64 Laser light 65 Glass plate 66,67 Laser beam 71 Stator 72,73 Comb-shaped electrode 74 Movable element 75,76 Laser beam 77 Glass plate 78 Laser light

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Iwao Hatakeyama 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (3)

[Claims] 1. Light that moves the mover by electrostatic interaction between a periodic charge distribution generated in a mover and a static charge distribution of a stator facing the mover by irradiation of light from a light source. A control-type electrostatic drive actuator, wherein at least the mover is made of a photovoltaic crystal material that is irradiated with light to generate an electric current. 2. The light source is divided into two, and an optical system is provided in which both of the two divided lights are simultaneously irradiated to the mover with an optical path difference that causes coherence. Item 2. The light control type electrostatic drive actuator according to Item 1. 3. The light-controlled static electricity according to claim 2, further comprising an optical system in which at least one of the bisected light beams emitted to the movable element has a variable irradiation direction. Drive actuator.