JPH052973A - Electrostatic relay - Google Patents

Abstract

PURPOSE:To allow an electrostatic relay to stand the influence of external electromagnetic field and thermal shock, enhance the inter-contact withstand voltage, and lower the drive voltage by forming both a movable side base and a stationary side base from an electroconductive material, and furnishing an electret between a movable side driving electrode and a stationary side driving electrode. CONSTITUTION:Bases A, B consisting of an electroconductive material such as Si monocrystal are arranged in electrical continuity at their joint surfaces D so that a movable contact 2 on the rear of a movable side base A and a stationary contact 3 on the front of a stationary side base B are facing each other. Thereby the stress and strain when thermal shock is applied are lessened, and influence of external electromagnetic field is reduced. An electret 8 is furnished between driving electrodes 11, 22 to strengthen the electrostatic power generated through impression of driving voltage, and thereby the contact is opened and shunt by displacing the movable part 12. Thus the inter-contact withstand voltage can be enhanced by lowering the driving voltage or widening the contact gap, compared with a conventional arrangement where no such an electret 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 relay that uses electrostatic force (Coulomb force) to contact and separate contacts.

[0002]

2. Description of the Related Art An electrostatic relay, unlike an electromagnetic relay, does not require an electromagnetic coil and can be further miniaturized.
Development is actively progressing. A device size of 10 mm □ or less is possible. 8 and 9 show a conventional electrostatic relay. In this electrostatic relay 191, the movable contact 194 provided on the back side of the movable base A and the fixed contact 197 provided on the front side of the fixed base B face each other so that the movable base A and the fixed base B are opposed to each other. Are arranged. The two bases A and B are joined via a spacer C.

The movable base A has a movable plate (movable portion) 192 having a movable contact 194 on its back surface, and a support portion (frame portion) for movably supporting the movable plate 192 such that the movable contact 194 and the fixed contact 197 come into contact with and separate from each other. ) 193. Then, the movable plate 192 approaches the fixed-side substrate B by an electrostatic force generated by applying a drive voltage between the movable plate 192 which also serves as the drive electrode of the movable-side substrate A and the drive electrode 198 of the fixed-side substrate B, and both of them are moved. The contacts 194 and 197 contact each other, and the movable plate 192 restores to its original horizontal state by its own spring property as the electrostatic force disappears, and thus the movable plate 192 moves away from the fixed side base B and the contacts 19
4,197 are separated.

The movable base A is formed with a necessary structural portion by processing a silicon substrate by a fine processing means such as selective etching, while the fixed side base B is a glass substrate. The movable contact 194, the fixed contact 197, or the fixed side drive electrode 198 is formed by forming a metal thin film, patterning, or the like.

[0005]

As can be seen from the above structure and operation, the electrostatic relay can be manufactured by utilizing the semiconductor element manufacturing technology such as the photolithography technology and the microfabrication technology. , Very small size can be manufactured, the volume can be reduced to 1/10 or less compared to the conventional electromagnetic relay, high speed operation is possible, heat generation during use is very small, and the cost is low. There are advantages such as mass production.

However, the above electrostatic relay has a problem that it is easily affected by an external electromagnetic field and that it is weak against thermal shock. In the electrostatic relay described above, since the glass substrate of the fixed side base B is an insulating material, when the electrostatic relay is placed in a field strongly influenced by electromagnetic induction from the outside or a field of a strong electric field, static electricity due to a driving voltage is applied. The power fluctuates and malfunctions.

Further, the silicon substrate of the movable base A and the glass substrate of the fixed base B have greatly different coefficients of thermal expansion, and the difference in dimensional variation between the bases A and B upon thermal shock is large. Large strains and stresses are generated, which causes damage. The conventional electrostatic relay operates with the electrostatic force (Coulomb force) generated by the drive voltage applied between the two drive electrodes on the movable side and the fixed side, but in order to secure sufficient contact pressure. The distance between both drive electrodes is shortened. This is because the electrostatic force is inversely proportional to the square of the distance between both drive electrodes, while the contact pressure is proportional to the electrostatic force. However, since the distance between both drive electrodes is shortened, there is a problem that the breakdown voltage between the contacts is inevitably lowered.

In the case of an electrostatic relay, the driving voltage for obtaining the necessary electrostatic force is high (usually several tens V to several hundreds V), which makes it difficult to use, and a reduction in the driving voltage is desired. .
Since the signal voltage of an ordinary electronic circuit is about several V to several tens of V, a booster circuit is required. The lowering of the driving voltage causes the external circuit to be unnecessary or reduced. In view of the above circumstances, it is an object of the present invention to provide an electrostatic relay that is not easily affected by an external electromagnetic field, is resistant to thermal shock, and can improve contact breakdown voltage and drive voltage. .

[0009]

In order to solve the above-mentioned problems, the electrostatic relay according to the present invention has a movable contact provided on the back side of the movable base and a fixed contact provided on the front side of the fixed base. The movable side base body and the fixed side base body are arranged so that the contacts face each other, and the movable side base body has a movable part having the movable contact point on the back surface, and the movable part has a movable contact point and a fixed contact point that can be displaced. In a configuration in which the movable portion is displaced by the electrostatic force generated by the application of the drive voltage to the drive electrodes in the both bases to bring the contacts into and out of contact with each other, Both the movable side base body and the fixed side base body are made of a conductive material, and an electret for enhancing electrostatic force at the time of displacement is provided between the fixed side drive electrode and the movable side drive electrode.

As the substrate made of a conductive material, for example, a silicon substrate may be mentioned. As a concrete example of the movable side and the fixed side, as in claim 3, an insulating film is formed on the surface of the movable side substrate, and a movable contact and a movable side drive electrode are formed thereon. An example is a mode in which an insulating film is formed on the surface of the fixed-side substrate, and a fixed contact and a fixed-side drive electrode are formed thereon. Further, it is preferable that the movable side base body and the fixed side base body are electrically connected to each other and have the same electric potential.

Further, as an example of a mode for enhancing the utilization of the electrostatic relay, there is a mode in which a driving circuit section is provided on the movable side base body and / or the fixed side base body as described in claim 5. As described above, in the case of the electrostatic relay, a driving voltage of tens of volts to hundreds of volts is usually required. Therefore, a booster circuit for driving voltage generation is required. Further, after the drive voltage is released, the contacts do not open unless the electric charge accumulated between the drive electrodes is discharged, and therefore a discharge circuit is usually required. Even though the electrostatic relay itself is small, it is difficult to use because it is necessary to add external circuits such as a booster circuit and a discharge circuit.

Specific examples of the driving circuit section include a mode having a discharge circuit and a mode having at least a part of a drive voltage generating booster circuit. The driving circuit unit does not have to include all circuits necessary for driving, and may have only some circuits. For example, there is a mode in which a part of the booster circuit and the discharge circuit are included. Of course, a mode in which all circuits necessary for driving are included is desirable. The driving circuit unit may be provided on either the movable side base body or the fixed side base body, or may be divided and provided on both base bodies.

The electret provided between the movable side drive electrode and the fixed side drive electrode includes an insulator having positive and / or negative charges and holding a charge whose sum is not 0, but is not limited thereto. Absent. Various materials and thicknesses can be used for the electret. For example, a polypropylene having a thickness of 5 μm and charged by corona discharge is exemplified.

Next, a specific example of the structure of the driving circuit section will be described. As shown in FIG. 5, the drive circuit section usually includes a booster circuit and a discharge circuit, and a signal voltage is boosted by the booster circuit and applied as a drive voltage between the movable side drive electrode 16 and the fixed side drive electrode 22. To be done. It goes without saying that the discharge circuit does not perform the discharge operation when the drive voltage is applied. When the drive voltage application is stopped, the discharge circuit quickly discharges the electric charge accumulated between the drive electrodes 16 and 22.

A more specific circuit example of the driving circuit section is shown in FIG.
Shown in. In the case of FIG. 6, a light emitting diode (light emitting element) 10
0 and a photocell array 101 in which a plurality of photocells 102 ... Which generate electromotive force in response to light from the light emitting diode 100 are connected in series constitutes a booster circuit, which includes a normally-off NPN transistor 103, a resistor 104, and a diode. A discharge circuit is composed of 105.

The operation of the drive circuit section shown in FIG. 6 is as follows. When the light emitting diode 100 emits light with a low signal voltage, a driving voltage higher than the signal voltage is generated in the photo cell array 101. The number of photovoltaic cells 102 is adjusted so that the required voltage level can be obtained. During the generation of the drive voltage, the transistor 103 is in the off state, and the drive voltage is normally applied between the drive electrodes 16 and 22 to be charged. When the signal voltage disappears, the drive voltage disappears, but the voltage due to the accumulated charge between the drive electrodes 16 and 22 turns on the transistor 103 and starts discharging the accumulated charge.

The drive circuit section is not limited to the above. For example, as the booster circuit, a charge pump type circuit in which n diodes and n capacitors are connected in series and parallel, or a thin film transformer type rectifier booster circuit in which a thin film transformer and a rectifying unit of a diode and a capacitor are combined can be used. However,
These booster circuits receive an AC signal voltage as an input. The electrostatic relay of this invention is not limited to the above configuration. For example, one of the movable and fixed drive electrodes is provided on the insulating film of the base, but the other drive electrode may be formed by the whole or a part of the conductive base itself. In this case, since the step of forming the drive electrode and the insulating film covering the drive electrode can be omitted, there is an advantage that the manufacturing process can be simplified and the cost can be reduced.

[0018]

In the electrostatic relay of the present invention, both the movable side base body and the fixed side base body are conductive materials. Therefore, the difference in the coefficient of thermal expansion is small and the strain and stress that occurs when a thermal shock is applied is small, so it is strong against thermal shock, and the section sandwiched between both conductive substrates becomes an electrical shield section. The influence of the electromagnetic field is reduced, and malfunction due to external factors hardly occurs.

Further, since there is an electret between the fixed-side drive electrode and the movable-side drive electrode, and the electrostatic force increases, the drive voltage can be lowered or the contact gap can be increased to improve the breakdown voltage between the contacts. The contact pressure can be increased if the drive voltage and the contact gap remain unchanged. If the movable side base and the fixed side base are both silicon substrates, the thermal expansion coefficient of both bases is the same, so the strain and stress when subjected to a thermal shock are extremely small, so it is extremely strong against thermal shock. Become. Further, in the case of a silicon substrate, it can also be used to fabricate elements such as transistors and resistors for the driving circuit section. It is possible to make the entire unit including the drive circuit unit extremely small.

When both movable and fixed contacts and both drive electrodes are formed on the insulating film on the surface of the substrate, both contacts and both drive electrodes can be sufficiently electrically shielded by both conductive substrates. Therefore, the influence of the external electromagnetic field is extremely reduced, and as a result, malfunction due to external factors is extremely unlikely to occur. When the movable base and the fixed base are at the same potential, a state in which no electric field is applied between the two bases is surely maintained, and therefore the stability is very high.

Further, if the drive circuit portion is provided on the base, the addition of an external circuit is unnecessary or reduced correspondingly, which facilitates the use.

[0022]

Embodiments of the present invention will be described in detail below with reference to the drawings. It goes without saying that the present invention is not limited to the following embodiments. FIG. 1 shows a main configuration of an electrostatic relay according to an embodiment. FIG. 2 shows a state where the entire electrostatic relay of the embodiment is viewed from above. FIG. 3 shows the periphery of the drive circuit portion of the electrostatic relay of the embodiment. FIG. 4 shows the XX cross section of FIG.

The electrostatic relay 1 of the embodiment has a relay section and a driving circuit section. The relay section will be described first, and then the driving circuit section will be described. In the relay section of the electrostatic relay 1,
Both bases A and B are arranged so that the movable contact 2 provided on the back side of the movable base A and the fixed contact 3 provided on the front side of the fixed base B face each other. Both of these substrates A,
B is joined so that electrical continuity can be obtained at the joint surface D. In this case, a conductive paste is applied and bonded to ensure electrical continuity and bond. Although other bonding methods are available, when a bonding method that does not allow electrical conduction is used, the substrates A and B are subjected to a treatment for electrical conduction after the bonding.

The movable base A has a movable plate (movable portion) 12 having a movable contact 2 on its back surface, and a support portion (frame portion) for movably supporting the movable plate 12 such that the movable contact 2 and the fixed contact 3 come into contact with and separate from each other. ) 13. The movable plate 12 is connected to the supporting portion 13 by the T-shaped connecting portion 14 to realize a displaceable supporting state. The movable plate 12 has, for example, a thickness of 30 μm, and is located at a position slightly recessed from the bottom of the support portion 13, for example, at a position retracted by 50 μm.

The movable side substrate A is made of a silicon single crystal substrate having a (100) plane on its surface. The above structure is relatively easy by using an aqueous potassium hydroxide etchant and a silicon nitride film as a mask material. Can be made into An insulating film 15 is formed on the back surface of the movable plate 12 (the surface on the side of the fixed base B). The movable contact 2 made of a metal thin film is patterned on the tip region of the insulating film 15, and the movable side drive electrode 16 made of a metal thin film is patterned on the central region. The drive electrode 16 is covered with an insulating film 17 to ensure necessary electrical insulation. A connection line 16a extends from the drive electrode 16, and the connection line 16a is also covered with an insulating film 17. The insulating film 17 is electrically connected to a portion E connected to the drive voltage introducing terminal 29 of the fixed side base B. It is a pattern that is not covered for connection. The connection at the connection portion E can be performed by, for example, the gold eutectic method.

The fixed side substrate B is also made of a silicon single crystal substrate, an insulating film 21 is formed at a position facing the movable plate 12, and a fixed contact 3 made of a metal thin film is formed in a pattern on the tip region of the insulating film 21. The fixed-side drive electrode 22 made of a metal thin film is patterned in the central region. The insulating film 21 is also formed in a necessary portion such as a drive circuit formation area.

The fixed contact 3 faces the movable contact 2, and the fixed side driving electrode 22 is formed in a pattern facing the movable side driving electrode 16. The fixed side drive electrode 22 is also covered with the insulating film 23 to ensure the necessary electrical insulation. The tip of the connection line 22 a of the drive electrode 22 has a drive voltage introduction terminal 28.
Connected to. In addition, connection terminals 30 and 30 are provided at the tips of the fixed contacts 3, respectively. Further, as shown in FIG. 4, a part of the bottom of the support portion 13 is recessed by, for example, about 50 μm so that the connection line of the fixed contact 3 and the support portion 13 do not come into contact with each other.

The movable contact 2, the insulating films 15 and 17, and the drive electrode 16 can be formed by a well-known thin film forming process, semiconductor process, photolithography technique, or the like. Moreover, various materials can be selected according to the purpose. Fixed contact 3, insulating films 21 and 23, movable side drive electrode 2
2. The terminals 28 to 30 can also be formed by using well-known thin film forming process, semiconductor process, photolithography technique, or the like. Moreover, various materials can be selected according to the purpose.

The contacts 2, 3 and the drive electrodes 16, 22 are formed by patterning a gold thin film having a thickness of 0.5 μm by a vacuum deposition method by photolithography. Insulating film 15,
21 is a silicon oxide thin film having a thickness of 1 μm deposited by atmospheric pressure CVD method and patterned by photolithography technique. The insulating films 17 and 23 are formed by depositing a silicon oxide thin film having a thickness of 1 μm by a plasma CVD method and patterning by a photolithography technique. Terminals 28-30
Is an aluminum thin film having a thickness of 1 μm formed by a vacuum evaporation method and patterned by a photolithography technique.

The electrostatic relay 1 is composed of the drive electrode 1
An electret 8 is provided between 6 and 22. As shown in FIG. 2, the electret 8 having substantially the same size as the driving electrodes 16 and 22 is formed on the insulating film 23.
They are stacked so that they face each other.
The electret 8 of the example has a relative dielectric constant of about 2 and is made of polypropylene and has a thickness of 5 μm. The electric charge held in the electret 8 is selected according to the operating state of the relay, but in the case of this embodiment, the electret 8 is used.
Of the movable side drive electrode 16 side is charged negatively and the opposite side is charged positively,
At the same time, the total amount of these charges is zero. There are various charging methods, but in this case, corona discharge is used.

Electret 8 thus formed
The electrostatic relay 1 using is operated in a single mode such that the contacts 2 and 3 are stable when the driving voltage is not applied (the applied voltage is 0), and the movable side driving electrode 16 has a positive voltage. When the drive voltage is applied so that the contact will be closed.
It goes without saying that the electrostatic force is increased by the presence of the electret 8.

The enhancement of the electrostatic force will be specifically described based on a simple model. As shown in FIG. 7, the configuration around the drive electrode and the electret of the electrostatic relay is such that two electrodes a and b are arranged at a distance (d ₁ + d ₂ ) and an electret c having a thickness d ₂ is placed on the electrode b. Is approximated with the. However, ε ₁ is the permittivity of air, and ε ₂ is the permittivity of the electret c. σ _{1 and} σ ₂ are the surface charges of the electret.

If there is no electret c, d ₂
As = 0, the force Fx acting on the electrode a is _{Fx = -ε 1 A (V /} d 1) 2/2 [where: A-is the area of the electrode and the electret]
Becomes On the other hand, when there is an electret c, the electrode a
Force acting on Fy is, Fy = -ε ₁ A [(Va-V) / L] a ^2/2. Here, if the electret c has only surface charges, Va = σ ₂ d ₂ / ε ₂ , L = (ε ₁ d
₂ / ε ₂ ) + d ₁ , so Fy = −ε ₁ A {[(σ
₂ d ₂ / _{ε 2)} -V] / _{[(ε 1 d 2 / ε 2} ) +
d _1]} becomes ^2/2.

Further, σ ₁ + σ ₂ = 0, σ ₁ > 0, σ ₂
When <0, the ratio Fy / Fx with and without the electret c is: {[(σ ₂ d ₂ / ε ₂ ) -V] d ₁ / [(ε ₁ d ₂ / ε ₂ ) + d ₁ ] Since V} ² = {[(σ ₂ d ₂ / ε ₂ V) -1] / [(ε ₁ d ₂ / ε ₂ d ₁ ) +1]]} ² , σ ₂ <0, V> 0. Then, since 1- (σ ₂ d ₂ / ε ₂ V)> (ε ₁ d ₂ / ε ₂ d ₁ ) +1, therefore, when V <−σ ₂ d ₁ / ε ₁ , the electret c is provided. The stronger the electrostatic force acting on the electrode a is when it is used.

For example, when the interelectrode gap is 30 μm and there is no electret c, Fx and the interelectrode gap are 50.
When there is an electret c having a surface charge of −5 × 10 ⁻⁴ C / m ² at μm, a thickness of 5 μm, and a relative dielectric constant of 2, Fy = −ε ₁ × A × 1.1 × when the driving voltage is 100V. 10 ¹³ ÷ 2 Fy = −ε ₁ × A × 2.6 × 10 ¹³ ÷ 2, which means that with the electret c, the force is more than twice as strong although the gap between the electrodes is larger.

Next, the drive circuit section will be described. The drive circuit section is provided centering on one side of the fixed-side base body B. FIG. 6 shows an equivalent circuit of the driving circuit section. The drive circuit unit includes a booster circuit and a discharge circuit. The booster circuit is
Red light emitting diode 100 and this light emitting diode 1
A large number of photovoltaic cells 102 that generate electromotive force by receiving 00 light
A large number of ... Are connected in series in the photo cell array 101.
It consists of and. Each photovoltaic cell 102 has a tandem configuration in which three pin type amorphous silicon photovoltaic cell elements are stacked, and 30 cells are connected in this photo cell array. The discharge circuit is composed of a normally-off NPN transistor 103, a resistor 104, and a diode (or diode array) 105. Since the operation of the circuit is as described above, the description thereof will be omitted. The light emitting diode 100 can be stacked on the photo cell array 101, for example, with a translucent insulating film interposed therebetween, or can be arranged with a space. Further, only the light emitting diode 100 may be externally attached. In this case, only a part of the booster circuit is built-in.

Finally, the operation of the electrostatic relay will be described. When a signal voltage is applied to the light emitting diode 100, a drive voltage is generated in the photocell array 101, which is applied between the drive electrode 16 of the movable side base A and the drive electrode 22 of the fixed side base B, and at the same time, the transistor 103. Turned off,
The movable plate 12 is fixed to the base body B by the electrostatic force generated by applying the driving voltage.
The contacts 2 and 3 come into contact with each other. Light emitting diode 10
When the signal voltage is not applied to 0, the voltage generation in the photo cell array 101 is stopped and the transistor 1
03 is turned on, the accumulated charge is discharged, the electrostatic force disappears, and the movable plate 12 returns to the original horizontal state by its own spring property, so that the contacts 2 and 3 separate from the fixed-side base body B.

[0038]

As described above, in the electrostatic relay according to the invention described in claims 1 to 5, since the strain and the stress upon receiving the thermal shock are reduced, the electrostatic relay is strong against the thermal shock and the external Since the influence of the electromagnetic field is reduced, malfunctions due to external factors are less likely to occur.Furthermore, there is an electret between the fixed-side drive electrode and the movable-side drive electrode, which increases electrostatic force. In addition, the drive voltage can be lowered and the contact gap can be increased to improve the breakdown voltage between contacts, which is extremely practical.

In the case of the electrostatic relay according to the second aspect, since the strain and the stress upon receiving the thermal shock are extremely small, it is extremely strong against the thermal shock, and the substrate is used for forming the element of the driving circuit section. Can be used as it is, and there is an advantage that the entire size including the drive circuit can be made extremely small. In the case of the electrostatic relay according to the third aspect, there is an advantage that the influence of the external electromagnetic field is extremely small and the malfunction due to the external factor is extremely unlikely to occur.

In the case of the electrostatic relay according to the fourth aspect, since a state in which no electric field is applied between the two bases is always maintained,
It has the advantage of being very stable. In the case of the electrostatic relay according to the fifth aspect, since the drive circuit portion is provided on the base body, the addition of an external circuit can be omitted or reduced, which is advantageous in that it is easy to use.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a main part of an electrostatic relay according to an embodiment.

FIG. 2 is a plan view showing a state of the electrostatic relay of the embodiment as viewed from above.

FIG. 3 is a plan view showing details of a driving circuit portion of the electrostatic relay of the embodiment.

FIG. 4 is a sectional view taken along line XX of FIG.

FIG. 5 is a block diagram showing a configuration example of a driving circuit unit of the electrostatic relay of the present invention.

FIG. 6 is a circuit diagram showing a specific configuration example of a drive circuit portion of the electrostatic relay of the present invention.

FIG. 7 is a schematic cross-sectional view showing a model configuration around a drive electrode and an electret of an electrostatic relay.

FIG. 8 is a plan view showing a conventional electrostatic relay.

FIG. 9 is a sectional view showing a conventional electrostatic relay.

[Explanation of symbols]

1 electrostatic relay 2 movable contacts 3 fixed contacts 8 electrets 12 Moving part 13 Support 16 Movable side drive electrode 22 Fixed side drive electrode A movable base B Fixed side substrate

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[Procedure amendment]

[Submission date] September 11, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction content]

The drive circuit section is not limited to the above. For example, as the booster circuit, a charge pump type circuit in which n diodes and n capacitors are connected in series and parallel, or a thin film transformer type rectifier booster circuit in which a thin film transformer and a rectifying unit of a diode and a capacitor are combined can be used. The electrostatic relay of this invention is not limited to the above configuration. For example, one of the movable and fixed drive electrodes is provided on the insulating film of the base, but the other drive electrode may be formed by the whole or a part of the conductive base itself. In this case, since the step of forming the drive electrode and the insulating film covering the drive electrode can be omitted, there is an advantage that the manufacturing process can be simplified and the cost can be reduced.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiromi Nishimura             1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.             Inside the company (72) Inventor Fumihiro Kasano             1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.             Inside the company (72) Inventor Takayoshi Awai             1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.             Inside the company

Claims (5)

[Claims] 1. The movable side base and the fixed side base are arranged so that the movable contact provided on the back side of the movable side base and the fixed contact provided on the front side of the fixed side base face each other, and the movable side. The base body includes a movable portion having the movable contact on the back surface and a support portion that movably supports the movable portion such that the movable contact and the fixed contact come in contact with each other. By applying a drive voltage to the drive electrodes of both the base bodies, In an electrostatic relay in which the movable portion is displaced by the generated electrostatic force to bring the contacts into and out of contact with each other, both the movable side base body and the fixed side base body are made of a conductive material, and the fixed side An electrostatic relay characterized in that an electret for enhancing electrostatic force at the time of displacement is provided between the drive electrode and the movable drive electrode. 2. The electrostatic relay according to claim 1, wherein the movable side base body and the fixed side base body are silicon substrates. 3. An insulating film is formed on the surface of the movable side substrate, a movable contact and a movable side drive electrode are formed thereon, and an insulating film is formed on the surface of the fixed side substrate. The electrostatic relay according to claim 1 or 2, wherein a fixed contact and a fixed side drive electrode are formed on the fixed contact. 4. The electrostatic relay according to claim 1, wherein the movable side base and the fixed side base are electrically connected and have the same potential. 5. The electrostatic relay according to claim 1, wherein a drive circuit section is provided on the movable side base body and / or the fixed side base body.