JPH0522959A - Electrostatic actuator - Google Patents

Abstract

PURPOSE:To provide an electrostatic actuator improved so as to be able to generate high force density at low driving voltage. CONSTITUTION:In an electrostatic actuator composed by arranging a stator 3, in which strip electrodes 2 are disposed at regular intervals to an insulating supporter 1, and a moving body 6, in which positive and negative charges are charged to an insulating sheet body 4, so as to be brought into contact, the insulating supporter 1 positioned at the upper section of at least the strip electrode of the stator and/or the insulating sheet body 4 of the moving body is constituted of a dielectric material having a dielectric constant of four or more. A surface on the side brought into contact with the moving body of the stator 3 and/or a surface on the side brought into contact with the stator of the moving body 6 is roughened or a lubricant layer is formed on the surface in a favorable type.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic actuator, and more particularly to an electrostatic actuator improved so as to generate a high force density with a low driving voltage.

[0002]

2. Description of the Related Art An electrostatic actuator comprises a stator in which strip electrodes are arranged at a predetermined interval on an insulating support, and a mover in which a resistive layer is provided on an insulating thin film such as an insulating film. The stator and the mover are arranged so as to be in contact with each other. Then, due to the action of static electricity, the mover is instantly levitated and moved while preventing friction (1989 Proceedings of the Annual Conference of the Institute of Electrical Engineers of Japan, 6-1).
91, Nikkei Mechanical 1989.5.29, 112-1
13 pages).

The electrostatic actuator is characterized in that the size of the electrodes and the gap can be reduced to increase the force density and can be easily miniaturized. Therefore, the electrostatic actuator is expected to be applied as a small driving device such as a sheet conveying mechanism in a word processor or a facsimile, and as a driving device for other minute mechanical systems.

FIGS. 1A to 1D are explanatory views of the driving principle of an electrostatic actuator (electrostatic film actuator) in which a moving element is made of an insulating film.
(1) is an insulating support, (2) is a strip electrode, (3) is a stator, (4) is an insulating film, (5) is a resistor layer,
(6) indicates a mover, and (7) to (9) indicate electric wires.

First, as shown in FIG. 1A, a positive voltage is applied to the electric wire (7) and a negative voltage is applied to the electric wire (8). Thereby, due to the potential difference between the electric charge existing in the electrode connected to the electric wire (7) and the electric charge existing in the electrode connected to the electric wire (8),
An electric current flows through the resistor layer (5), and charges are induced at the boundary between the insulating film (4) of the mover (6) and the resistor layer (5) to reach an equilibrium state. This charge is shown in FIG.
It can be replaced by the image charge shown by the dotted line in (b). The polarities of the electric charges and the polarities of the electric charges are different from each other. Therefore, in the state of FIG. 1B, the mover (6) is attracted to the stator (3).

Next, as shown in FIG. 1C, a negative voltage is applied to the electric wire (7), a positive voltage is applied to the electric wire (8), and a negative voltage is applied to the electric wire (9). As a result, the charge in the electrode can be instantaneously moved, but the induced charge of the mover (6) cannot be immediately moved because the resistance value of the resistor layer (5) is high. as a result,
A repulsive force is generated between the mover (6) and the stator (3). By the repulsive force being generated, the friction between the stator (3) and the mover (6) is reduced, and the negative charge and positive induced charge (image charge due to the image charge) generated as a result of applying a voltage to the electric wire (9). Speaking of), a driving force in the right direction is generated.

FIG. 1D shows the result of the mover (6) moving to the right by one pitch of the electrode due to the driving force. When moving the mover (6) to the left,
A positive voltage may be applied to the electric wire (9). In the applied voltage pattern (the pattern shown in FIG. 1C) in the above-described movement operation for each pitch of the electrodes, the electric wires (7) and (8) have the voltages opposite to those in the state shown in FIG. 1 (c), the induced charge (and, in terms of the image charge) in FIG. 1C is attenuated.

Therefore, in order to continuously move the mover (6) to the right by one electrode pitch, it is necessary to repeatedly apply a voltage having the following pattern in which the charge charging operation and the moving operation are repeated. . The voltage pattern illustrated in the following [Table 1] is a one-cycle voltage pattern,
(G) shows a state in which no voltage is applied, (C) and (A) show a charge charging operation and a transfer operation, respectively.
The first (C) is the state shown in FIG. 1 (a), and the first (A) is the state shown in FIG. 1 (c).

[0009]

[Table 1]

In order to stably and continuously move the electrostatic actuator for each pitch of the electrodes, the surface specific resistivity of the mover (6) (resistor layer (5)) is 10 ¹² to 10 ¹⁵ Ω /
It is said that it must be in the range of □. The reason is as follows. That is, when the surface specific resistance of the mover (6) is large, it takes a relatively long time to charge the charge, and when it is small, the induced charge is instantly attenuated.
However, in the case of the electrostatic actuator shown in FIG. 1, since the resistance value of the insulating film forming the moving element is too large, the resistance layer as described above is provided on the insulating film to reduce the conductivity. Need to be imparted. In addition,
As a matter of course, in the known electrostatic actuator shown in FIG. 1, the insulating film (4) may be replaced with another insulating thin leaf member having a resistance value similar to this.

[0011]

However, the electrostatic actuator is still in the research stage, and in order to put it into practical use, it is necessary to examine the details of each element. In particular, the driving voltage requires a high voltage of 500 to 1000 V, and therefore, the lowering of the driving voltage is desired for practical application of the electrostatic actuator. The present invention has been made in view of the above circumstances, and an object thereof is to provide an electrostatic actuator improved so as to generate a high power density with a low driving voltage.

[0012]

In order to achieve the above-mentioned object, the present inventor has made various studies by paying attention to a structure similar to the capacitor of an electrostatic actuator, and as a result, made a specific material for the electrostatic actuator. The present invention has been completed based on the knowledge that the above object can be easily achieved with the above structure. That is, the gist of the present invention is to provide an electrostatic actuator in which a stator in which strip electrodes are arranged at a predetermined interval on an insulating support and a moving element to which positive and negative charges are applied to an insulating thin leaf are arranged in contact with each other. And an electrostatic actuator characterized in that an insulating support located at least above the strip-shaped electrode of the stator and / or an insulating thin leaf of the mover is made of a dielectric material having a relative dielectric constant of 4 or more. .

The present invention will be described in detail below. In the basic configuration of the electrostatic actuator of the present invention, the constituent material of the moving element (6) is not limited to the insulating film in FIG.
Further, it is the same as the known electrostatic actuator shown in the figure, except that the structure of the moving element is not limited to the one provided with a resistor layer. Therefore, in the following description,
For the sake of convenience, reference is made to FIG. 1 where (4) in FIG. 1 is an insulating thin leaf body. A feature of the present invention is that at least one of the stator and the mover is made of a dielectric material having a relative dielectric constant of 4 or more, so that a high power density can be generated at a low driving voltage. . The relative permittivity is defined as the ratio of the permittivity of a material to the permittivity in vacuum. The term “dielectric material” refers to a substance that produces a dielectric polarization when an electrostatic field is applied but does not produce a direct current, and is synonymous with an electrical insulator. In other words, a dielectric is a nomenclature of an insulator in terms of dielectric polarization.

First, the significance of using a dielectric material having a relative dielectric constant of 4 or more in the present invention will be described. Figure 2
Is a wire (7) of the electrostatic actuator shown in FIG.
It is a schematic explanatory view of 1 unit corresponding to (8). Then, such a unit can be considered in the same manner as a capacitor, and its capacitance can be expressed by the following mathematical expression [Formula 4].

[0015]

C = ε × w × l / d ε: Dielectric constant between capacitors ε = ε ₀ × ε _r (ε ₀ : dielectric constant in vacuum, ε _r : relative dielectric constant) w: width of strip electrode l: length of strip electrode d: gap length

The electrostatic energy (U) stored in the above capacitor is given by the following mathematical expression [Equation 5].

[0017]

[Equation 5] U = −1 / 2C × V ² = −ε × w × l × V ² / 2d V: potential between gaps

Since the strength (E) of the electric field is V / d, the above formula [Equation 5] can also be expressed by the following formula [Equation 6].

[0019]

[6] U = -ε × w × l × d × E 2/2

Therefore, in the electrostatic actuator, in order to increase the electrostatic energy (U) while reducing the driving voltage, a dielectric material having a large relative permittivity (ε _r ) is used between the capacitors. The dielectric constant (ε) may be increased or the electric field strength (E) may be increased. By the way, in order to increase the electric field strength (E) while reducing the driving voltage, it is necessary to make the electrode pitch finer. However, as described above, the strip electrode of the electrostatic actuator has a three-phase structure. Therefore, through-hole processing is required, and therefore, miniaturization of the electrode pitch has many problems in electrode processing. Therefore, according to the present invention, by using a dielectric material having a large relative permittivity (ε _r ), a high power density can be generated at a low driving voltage without causing the above problems in electrode processing. I did so.

Next, the stator (3) and the mover (6) in the electrostatic actuator of the present invention will be described. The stator (3) is formed by arranging the strip electrodes (2) on the insulating support (1) at predetermined intervals. The strip electrodes (2) arranged on the stator (3) may be provided on the surface of the insulating support (1) or may be embedded in the insulating support (1). . The interval between the strip electrodes (2) is not particularly limited, but is usually 0.1 to 2 mm, and in order to improve the driving performance such as the generated force of the electrostatic actuator and the drive voltage, the strip electrodes (2) are formed. Finer spacing is desirable. The mover (6) is formed by applying positive and negative charges to the insulating thin leaf body (4). The method for applying positive and negative charges to the insulating thin leaf body (4) is performed according to the method described later. The greatest feature of the present invention is the stator (1) and the mover (6).
In at least one of them, a dielectric material having a relative dielectric constant of 4 or more (hereinafter abbreviated as a dielectric material) is used.

Examples of the dielectric material include glass fiber-containing polyethylene terephthalate (ε _r = ˜4.5, measuring frequency is 1 kHz, the same applies hereinafter), polyvinylidene chloride (˜5), cellulose acetate (˜7), Phenolic resin containing glass fiber (7), urea resin containing α-cellulose (up to 7.5), soft polyvinyl chloride (4 to 8), melamine resin (up to 8), polyacrylonitrile (8), polyvinyl fluoride (8. 5), polyvinylidene fluoride (8-11), polyvinyl alcohol (9), various glasses (-10), cellulose (10), polyethylene oxide (15) and the like. Among these dielectric materials, those having a relative permittivity of 5 or more, particularly,
It is preferable that the dielectric constant is 7 or more. The dielectric material used in practice is selected from materials having a relative dielectric constant of 100 or less. Further, since the electrostatic actuator alternately applies positive and negative DC voltage according to the driving frequency, it is preferable to reduce the dielectric loss of the actuator. Therefore, a material having a small dielectric loss tangent is selected in combination with the relative dielectric constant. Is preferred.

Next, the case where a dielectric material is used for the stator (1) will be described. In this case, at least the insulating support (1) located above the strip electrode (2) needs to be made of a dielectric material. Then, the strip electrode (2) is embedded in the insulating support (1). Specifically, a strip electrode (2) is formed on the surface of an insulating support (1) made of an ordinary insulating material, and a film or sheet of a dielectric material is laminated thereon. As a usual insulating material, for example, a film or sheet of polyethylene terephthalate (ε _r = 2 to 3) is preferably used as in the known electrostatic actuator.

Next, the case where a dielectric material is used for the mover (6) will be described. In this case, the insulating thin leaf body (4) of the mover may be made of a dielectric material. As a method of applying positive and negative charges to the insulating thin leaf body (4), a method of providing a resistor layer (5) on the insulating thin leaf body (4) is similar to the known electrostatic film actuator shown in FIG. Can be mentioned. Specifically, for example, a method of applying an antistatic agent having a weak antistatic effect to the surface of the insulating thin leaf body (4) can be used. In this case, the surface resistivity of the resistor layer (5) is in the range of 10 ¹² to 10 ¹⁵ Ω / □, preferably 10 ¹⁴ Ω / □.
It is necessary to go back and forth. And the resistor layer (5)
The direction of installation may be either the surface of the mover (6) that contacts the stator (3) or the other surface, but the latter surface is preferred.

The method of applying positive and negative charges to the insulating thin leaf body (4) is not limited to the above method, and various other methods obvious to those skilled in the art can be adopted. For example, when the insulating thin leaf body (4) is made of an insulating film, a conductive substance such as carbon black is kneaded to make the insulating thin leaf body (4) itself a resistor having the same resistivity as above. A method of providing a strip electrode on the insulating thin leaf body (4),
Examples thereof include a method using an ion generator and a method using an electret material for the insulating thin leaf body (4).

The method of providing the strip electrodes on the insulating thin leaf body (4) is not particularly shown, but in FIG. 1, the strip electrodes of the two-phase structure corresponding to the electric wires (7) and (8) are used as the strip electrodes of the stator. This is a method provided correspondingly to (2), in which positive and negative voltages are constantly applied to these electric wires, and positive and negative charges existing in each strip electrode are used instead of the image charge and. In addition, the method of using an ion generator is to arrange an insulating thin leaf body (4) in contact with a stator (3) and apply positive and negative voltages to the electric wires (7) and (8) to induce electric charges. After that, from the ion generator known as a static eliminator (a device designed to apply positive and negative ion wind generated by applying an AC voltage to the needle electrode to cause corona discharge to a charged object with a blower) A method of applying an ionic wind to the surface of the insulating thin leaf body (4), wherein an ionized air layer formed on the surface of the insulating thin leaf body (4) is used instead of the image charge and. As the ion generating device, various static eliminators described in "Static Handbook" (Static Society of Japan, published by Ohmsha, 1st edition, page 819) can be used.

The thickness of the insulating thin leaf material (4) cannot be unconditionally determined because the force generated by the electrostatic actuator varies depending on the method of applying charges to the insulating thin leaf material, but it is usually 10 μm or more. It Then, when the method of providing the resistor layer (5) on the insulating thin leaf body (4) is adopted as the method of applying the electric charge, it is preferably in the range of 10 to 200 μm. Whatever method is used to apply the charge, the thickness of the insulating thin leaf body (4) is determined by setting the distance between the strip electrodes (2) arranged on the insulating support (1) as P and strip shape. The surface of the electrode (2), the insulating thin leaf body (4), and the resistor layer (5) (if the insulating thin leaf body (4) is provided with a strip electrode, the strip electrode is formed, and if an ionized air layer is formed, it is If the distance to the boundary surface between the
It is preferable to set the range to satisfy the relationship of <G / P <0.4.

In the electrostatic actuator of the present invention,
A dielectric material may be used for both the stator (1) and the mover (6), but a dielectric material may be used for only one of them. When a dielectric material is used only for the stator (1), for example, a film of polyethylene terephthalate is suitable for the insulating thin leaf body (4) of the moving element (6) as in the known electrostatic actuator. Although used, glass or ceramics having a resistance value similar to this and a relative dielectric constant of less than 4 can also be used. Mobile (6)
When a dielectric material is used only for the stator, for example, the stator (1) may be formed by forming the strip electrodes (2) on the surface of the insulating support (1) made of a polyethylene terephthalate film or sheet. In this case, it is not necessary to embed the strip electrode (2) in the insulating support (1).

By the way, in the electrostatic actuator,
In particular, if the insulating thin leaf of the mover is smooth, the air does not sufficiently enter between the stator and the mover, the friction between them becomes large, and the mover does not move smoothly. There's a problem. In particular, in the above charge operation, the friction between the mover and the stator is large because the mover is suction-adhered to the stator. In particular, moisture is adsorbed on the contact surface between the mover and the stator at room temperature and normal humidity in a thickness of at least nm order, and a bridge structure is formed between the stator and the mover. By the surface tension of the above-mentioned adsorbed water that formed,
There is a problem that the mover does not move smoothly.

In the present invention, in order to solve the above problems and achieve smooth driving of the electrostatic actuator, the contact surfaces of the stator (3) and the mover (6) are conformed to the preferred embodiments described below. Is roughened or a lubricant layer is provided on the contact surface. Of course, the surface may be roughened and a lubricant layer may be provided.

First, the roughening will be described. The above-mentioned roughening is carried out by the following mathematical expression on the surface of the stator (3) that is in contact with the mover (6) and / or the surface of the mover (6) that is in contact with the stator (3). An uneven pattern satisfying Expression 7 (the same as [Expression 1]) and [Expression 8] (the same as [Expression 2]) is provided, or the following mathematical expression [Expression 9] (the same as [Expression 3]). It is achieved by the satisfaction holes provided 0.1 pieces / cm ² or more.

[0032]

[Equation 7] 0.01 <h / t

[Equation 8] 10 (μm) <t

[Equation 9] 20 <D

In the above equations, h is the height (Rmax., Μm) of the convex portion of the concavo-convex pattern, and t is the thickness (μm) of the insulating thin leaf body (4) or the stator (3) of the moving element. , D represent the pore diameter (μm). And the insulating thin leaf body of the moving body (4)
The thickness of the insulating thin foil (4)
When the resistor itself is used, it means the thickness of the mover (6) itself, and when the insulating thin leaf (4) is provided with the resistive layer (5), the thickness of the resistive layer is ignored. Even if it is as thin as possible, it means the thickness of the moving element (6) itself.

According to the above roughening, the contact area between the stator (3) and the mover (6) can be reduced to reduce the friction,
The slipperiness of the mover (6) can be improved. The above roughening can be performed between the contact between the stator (3) and the mover (6), but one of them is a flat surface,
It is preferable to roughen only the other surface.

The method of forming the above-mentioned uneven pattern is not particularly limited, and may be changed depending on the kind of material of the surface on which the uneven pattern is provided.
The methods exemplified below can be appropriately adopted. (A) A method of coating a smooth surface with a coating liquid containing inorganic particles and the like (b) A method of adding a crystallization promoting treatment and a crystallization accelerator, etc. (c) Inorganic particles such as silicon dioxide, titanium dioxide and calcium carbonate, and Method of adding incompatible polymer etc. (d) Method of mechanical embossing or sandblasting (e) Method of surface treatment such as solvent treatment, corona discharge, plasma discharge, electron beam irradiation, X-ray irradiation (f) Method of transferring independent cells or grooves by gravure coating The above methods (b) and (c) are mainly applied when a synthetic resin is used. Of the above methods, the method (a) using spherical particles (for example, glass heats) having a substantially uniform particle size (in the range of 5 to 20 μm) as the inorganic particles is particularly preferable.

The holes can be easily formed by, for example, a mechanical punching method or another suitable method.

When the uneven pattern is provided on the surface of the stator (3), the height (Rmax.) Of the convex portion of the uneven pattern is preferably 5 μm or more. Moreover, it is preferable to provide the above-mentioned hole in the moving element.

Next, the formation of the lubricant layer will be described. The lubricant used in the present invention may be either a solid lubricant or a liquid lubricant at room temperature.

Examples of the solid lubricant include fatty acid metal salts such as sodium stearate, magnesium stearate and magnesium palmitate; fatty acid esters such as ethyl stearate and methyl palmitate; triglyceride stearate and triglyceride palmitate. Fats and oils; higher alcohols such as stearyl alcohol and hexadecanol; steroid compounds such as cholesterol and sitosterol, etc. are used, and in addition, Teflon, molybdenum disulfide, graphite and the like can be used.

Further, as the liquid lubricant, in addition to the usual hydrocarbon mineral oil type lubricating oil such as machine oil and engine oil,
Silicon oil such as dimethylpolysiloxane, fluorinated oil such as perfluoropolyether, and phosphoric acid ester can be used.

The above-mentioned lubricant is used after being dissolved or dispersed in a solvent. As the solvent, for example, alcohols, ketones, aromatic compounds, chlorine-based solvents and the like are appropriately used.

After the lubricant is dissolved or dispersed in a solvent, the mover (3) of the stator (3) is formed by a method such as a dip method, a spin coating method, a spray method, a gravure method, a knife coating method, a roll coating method or the like. 6) is applied to the surface of the side contacting 6) and / or the surface of the mover (6) contacting the stator (3) to form a lubricant layer.

The thickness of the lubricant layer is preferably in the range of 1 to 40 nm, more preferably 2 to 10 nm.

The electrostatic actuator of the present invention comprises the stator and the mover configured as described above, and is driven according to the same driving principle as a known electrostatic actuator.

[0045]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the following examples, the following materials and measuring methods were adopted.

(1) A belt-shaped electrode having a width of 0.2 mm and a pitch of 0.4 mm was formed on the surface of a polyethylene terephthalate film having a thickness of 125 μm, and the film described in each example was laminated on the surface. used.

(2) Measurement of force density The size of the moving element arranged in contact with the stator is 10 ×.
It was set to 10 cm, various weights were attached to the moving element, and how many g of weight could be pulled up in the vertical direction (direction opposite to the gravity direction) was measured. The measurement was performed by adopting the driving conditions shown in [Table 2] below and changing the driving voltage.

[0048]

[Table 2] <Drive conditions> Initial charging time: 10s Charging time: 450ms Travel time: 50ms Drive frequency: 2Hz Drive voltage: ± 800v

Example 1 A moving element is a polyethylene terephthalate film having a thickness of 25 μm (manufactured by Diafoil Co., Ltd., S type, ε _r =).
An antistatic agent having a weak antistatic effect was spray-coated on one surface of 3) (specific surface resistivity 1 × 10 ¹⁴ Ω /
□). The stator is 37 μm thick as a film for lamination.
Polyvinylidene Fluoride film (Kureha Chemical Industry Co., Ltd., KF film, ε _r = 10.7, thickness 12μ
m and 25 μm one were laminated). In the above electrostatic actuator, glass beads (particle diameter: 18 μm, Toshiba Ballotini, GB731M) were dispersed between the stator and the mover, and the relationship between the drive voltage and the power density was measured. The results are shown in [Table 3] below. The force density (N / m ² ) 30 corresponds to the force capable of lifting a weight of 30 g.

[0050]

[Table 3]

Example 2 The mover was formed by spray-coating an antistatic agent having a weak antistatic effect on one surface of the above-mentioned KF film having a thickness of 25 μm (surface specific resistance 1 × 10 ¹⁴ Ω / □). The stator is
As the laminating film, the above KF film having a thickness of 50 μm was used. In the above electrostatic actuator, magnesium stearate as a solid lubricant is applied to the sliding surfaces of the stator and the moving element to a thickness of 3 nm,
The relationship between drive voltage and power density was measured. The results are as shown in the following [Table 4].

[0052]

[Table 4]

Example 3 The mover was constructed by forming a strip-shaped electrode having a two-phase structure with an electrode width of 0.2 mm and an electrode pitch of 0.4 mm on the surface of the same polyethylene terephthalate film as used in Example 1. did. Regarding the above-mentioned electrostatic actuator, the same glass beads as in Example 1 were scattered between the stator and the mover, and a voltage of ± 600 v was applied to the strip electrode having a two-phase structure, and the driving voltage and the power density were changed. The relationship was measured. Result is,
It is as shown in the following [Table 5].

[0054]

[Table 5]

Example 4 As in Example 1, the polyethylene terephthalate film was placed in contact with the stator in the same manner as in Example 1 except that spray coating of the polyethylene terephthalate film was omitted. Then, with positive and negative voltages applied to the strip electrodes (electric wires (7) and (8) in FIG. 1) of the stator, ion wind was applied to the surface of the polyethylene terephthalate film to measure the relationship between the driving voltage and the power density. . The results are as shown in [Table 6] below. As the above-mentioned ionizer, a static eliminator SH-2 type manufactured by Japan Static Co., Ltd. was used. Further, in the continuous drive test, it was confirmed that the surface of the polyethylene terephthalate film was smoothly driven by continuously applying an ionic wind.

[0056]

[Table 6]

Example 5 The same stator as in Example 1 was used. The mover was formed by roughening one surface of the same polyethylene terephthalate film used in Example 1 according to the following procedure and spraying an antistatic agent having a weak antistatic effect on the opposite smooth surface (surface specific Resistivity 1 × 10 ¹⁴ Ω /
□).

<Roughening> Polyurethane resin coating liquid (solvent: tetradrofuran, solid content concentration: 15) containing hollow glass beads (manufactured by Toshiba Ballotini) having an average particle diameter of 10 μm.
% By weight, glass bead concentration: about 1% by weight) was applied with a bar coater and dried. The thickness of the coating film after drying is 1 to
It was 2 μm. Further, the surface roughness Rmax. Of the above-mentioned roughened film is measured, and the height (hμm) of the convex portion is calculated to obtain h /
When t was calculated, Rmax. = 8 μm, h /
It was t = 0.32.

By disposing the moving element and the stator so as to be in contact with each other, the electrostatic actuator of the present invention shown in the conceptual view of FIG. 3 was produced. In the above electrostatic actuator, a solid lubricant magnesium stearate having a thickness of 3 nm was applied to the sliding surfaces of the stator and the moving element, and the relationship between the driving voltage and the force density was measured. The results are shown in [Table 7] below. The magnesium stearate was applied using a spin coater using dioxane as a solvent.

[0060]

[Table 7]

Example 6 A stator was constructed by using, as a laminating film, borosilicate glass having a thickness of 30 μm (manufactured by Nippon Electric Glass Co., Ltd., ε _r = 6). The mover was formed by roughening one surface of the same polyethylene terephthalate film used in Example 1 according to the following procedure and spraying an antistatic agent having a weak antistatic effect on the opposite smooth surface (surface specific Resistivity 1 × 10 ¹⁴ Ω / □).

<Roughening> Polyurethane resin coating liquid containing polystyrene beads having an average particle size of 6 μm (Micropearl, manufactured by Sekisui Fine Chemical Co., Ltd.) (solvent: tetradrofuran, solid content concentration: 15% by weight, polystyrene bead concentration: about 1% by weight) was applied with a bar coater and dried. The thickness of the coating film after drying was 1-2 μm. Further, the surface roughness Rmax. Of the roughened film is measured,
When the height (hμm) of the convex portion was obtained and h / t was calculated, Rmax. = 4 μm and h / t = 0.16, respectively.

By disposing the moving element and the stator so as to be in contact with each other, an electrostatic actuator of the present invention shown in the conceptual view of FIG. 3 was produced. In the above electrostatic actuator, a solid lubricant magnesium stearate having a thickness of 3 nm was applied to the sliding surfaces of the stator and the moving element, and the relationship between the driving voltage and the force density was measured. The results are as shown in [Table 8] below.

[0064]

[Table 8]

Comparative Example 1 In Example 1, a polyethylene terephthalate film having a thickness of 37 μm (manufactured by Diafoil Co., S type, ε _r = 3, thickness 12 μm) was used as a film for laminating the stator.
The electrostatic actuator was constructed in the same manner as in Example 1 except that the stator was constructed by using two sheets of m and 25 μm. Regarding the above electrostatic actuator, the same glass beads as in Example 1 were scattered between the stator and the mover, and the relationship between the drive voltage and the power density was measured. It is as shown in the following [Table 9].

[0066]

[Table 9]

[0067]

According to the electrostatic actuator of the present invention described above, the dielectric film having a relative permittivity of 4 or more is used as the insulating support and / or the insulating film of the mover located at least above the strip electrodes of the stator. By being made of a material, high power density can be generated with a low driving voltage. Further, the electrostatic actuator of the present invention can be driven extremely smoothly. Therefore, the present invention largely contributes to the practical application of the electrostatic actuator.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a driving principle of an electrostatic actuator.

FIG. 2 is a schematic explanatory view of one unit corresponding to electric wires (7) and (8) of the electrostatic actuator shown in FIG.

FIG. 3 is a conceptual diagram showing an example of an electrostatic actuator according to a preferred embodiment of the present invention.

[Explanation of symbols]

(1): Insulating support (2): Strip electrode (3): Stator (4): Insulating film or insulating thin sheet (5): Resistor layer (6): Mover (7)-(9): Electric wire

Claims (3)

[Claims] 1. An electrostatic actuator comprising a stator in which strip electrodes are arranged at a predetermined interval on an insulating support and a mover in which positive and negative charges are applied to an insulating thin leaf are arranged in contact with each other. 2. An electrostatic actuator, characterized in that the insulating support and / or the insulating thin leaf of the mover located above at least the strip electrode is made of a dielectric material having a relative dielectric constant of 4 or more. 2. A concavo-convex pattern satisfying the following formulas [Equation 1] and [Equation 2] is formed on the surface of the stator that is in contact with the mover and / or the surface of the mover that is in contact with the stator. The holes that are provided or satisfy the following formula [Equation 3] are set to 0.
The electrostatic actuator according to claim 1, wherein the electrostatic actuator is provided at least 1 piece / cm ² . ## EQU1 ## 0.01 <h / t ## EQU00002 ## 10 (.mu.m) <t ## EQU3 ## 20 <D (In the above equations, h is the height of the convex portion of the concave-convex pattern (R
max., μm), t is the thickness (μm) of the insulating thin leaf body or stator of the mover, and D is the hole diameter (μm)) 3. The electrostatic actuator according to claim 1, wherein a lubricant layer is provided on the surface of the stator on the side of contact with the mover and / or on the surface of the mover on the side of contact with the stator.