JP2007312551A - Electrostatic induction type converting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic induction type converting device which properly maintain a mutual distance when substrates move relatively to each other. <P>SOLUTION: Two substrates 10, 12 are arranged oppositely each other, and electrets 14 and conductors 16 are formed on opposite faces of each substrate 10, 12. Moreover, the substrates 10, 12 move relatively in a direction parallel to the opposite faces (directions of arrow marks A, B in a Figure), and the electrets 14 move relatively to the conductors 16 involved in relative movement of the substrates 10, 12 to generate electromotive force to the conductors 16 by electrostatic induction. The electrets 14 and the conductors 16 are arranged so that attraction force generated by opposite arrangement of the electrets 14 and the conductors 16 may balance with repulsive force generated by opposite arrangement of the electrets 14, in order to properly maintain the distance between the substrates 10, 12. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an improvement of an electrostatic induction conversion element that converts electrical energy and kinetic energy.

Conventionally, a power generation device, a microphone, and the like using an electret in which an electric charge is injected into an insulating material have been proposed. In such an apparatus using an electret, it is known that the conversion efficiency between electric energy and kinetic energy is high. For example, Patent Document 1 below also discloses an example of an electrostatic actuator using an electret. 6A and 6B show a configuration example of this electrostatic actuator.
JP 2005-229707 A

  However, in the shape shown in FIG. 6A, which is the conventional technique, the electret on one side is uniformly formed with respect to the drive electrode, and thus cannot be applied to a power generator or a sensor. However, in the shape shown in FIG. 6B, if the drive electrode is considered as a power generation electrode for inducing charge, it can be a power generator. However, since the electret of the mover and the drive electrode attract each other at a position shifted by a half pitch from this figure, there is a problem that the mover and the fixed substrate are in close contact.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide an electrostatic induction conversion element capable of maintaining a mutual distance appropriately when substrates move relative to each other. It is in.

  In order to achieve the above object, the present invention provides an electrostatic induction conversion element that converts electrical energy and kinetic energy, the substrates facing each other and relatively moving in a direction parallel to the facing surface, and the substrate Electrets and conductors formed in a mixed manner on each of the opposing surfaces, wherein the electrets and the conductors are generated by the attracting force generated by the electrets and the conductors facing each other and the electrets facing each other. It arrange | positions so that a repulsive force may be substantially balanced.

  In the electrostatic induction conversion element, the total area of the electret and the conductor is a different value on at least one of the substrates.

  In the electrostatic induction conversion element, the electret and the conductor are formed in a strip shape.

  In the electrostatic induction conversion element, the electret and the conductor are arranged in a grid pattern.

  In the electrostatic induction conversion element, the electret may be PTFE (polytetrafluoroethylene), FEP (tetrafluoroethylene / hexafluoropropylene copolymer), PFA (tetrafluoroethylene / perfluoro (alkyl vinyl ether)). It is composed of a copolymer, silicon oxide, a polymer having a fluorine-containing aliphatic ring structure, or a solvent-soluble fluorine-containing resin.

  In the electrostatic induction conversion element, the polymer having the fluorine-containing aliphatic ring structure is obtained by subjecting the main chain to cyclopolymerization of a fluorine-containing monomer having two or more polymerizable double bonds. It is characterized by comprising a polymer having a fluorine-containing aliphatic ring structure.

  In the electrostatic induction conversion device, the fluorine-containing aliphatic ring structure contains one or less etheric oxygen atoms.

  According to each of the above configurations, it is possible to realize an electrostatic induction conversion element that is free from friction and can maintain the distance between each other properly when the substrates move relative to each other.

  Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings.

  1A and 1B are cross-sectional views showing a configuration example of an electrostatic induction conversion element according to the present invention. 1A and 1B, the electrostatic induction conversion element has two substrates 10 and 12 arranged to face each other, and electrets 14 and The conductor 16 is mixed and formed. Moreover, the said board | substrates 10 and 12 are comprised so that a relative motion may be carried out in the direction (arrow A, B direction of a figure) parallel to an opposing surface. Note that the mechanism for relatively moving the substrates 10 and 12 can be appropriately configured by a conventionally known method, and thus illustration and description thereof are omitted.

  The electret 14 is formed by injecting charges near the surface of an insulating material. For this charge injection, a known method such as liquid contact, corona discharge, electron beam, back-lit thyratron, or the like can be used. In addition, the electret 14 moves relative to the conductor 16 with the relative movement of the substrates 10 and 12, and causes the conductor 16 to generate an electromotive force due to electrostatic induction.

  The conductors 16 formed on the substrates 10 and 12 are connected to each other with the same phase of the electromotive force electrostatically induced by the relative motion with the electret 14 so that the induced electromotive force can be taken out from the terminals 18 and 20, respectively. It is configured. Thereby, kinetic energy can be converted into electric energy and taken out. With such a configuration, the electrostatic induction conversion element of the present invention can function as a generator or a sensor. Examples of application as a sensor include a microphone, a pressure sensor, an acceleration sensor, and a seismometer. When a power source is connected to the conductor 16, the substrates 10 and 12 can be moved in the directions of arrows A and B in FIGS. 1A and 1B by electric energy. In this case, the electrostatic induction conversion element of the present invention functions as an actuator.

  A characteristic point in the present embodiment is that the electret 14 and the conductor 16 are substantially balanced by the attractive force generated when the electret 14 and the conductor 16 face each other and the repulsive force generated when the electrets 14 face each other. It is in the point where it is arranged.

  That is, since charges of the same polarity are injected into the surface of the electret 14, a repulsive force is generated when the electrets 14 face each other, and an attractive force is generated when the electret 14 and the conductor 16 face each other. Therefore, the suction force and the repulsive force can be balanced by adjusting the total area where the electret 14 and the conductor 16 face each other and the total area where the electrets 14 face each other. In addition, since repulsive force and attraction | suction force do not arise in the conductors 16, it does not participate in the said balance.

In the example shown in FIG. 1A, the area ratios occupied by the electrets 14 in the total area of the substrates 10 and 12 are x (substrate 10) and z (substrate 12), respectively, and the area ratios occupied by the conductors 16 are respectively Assuming y (substrate 10) and w (substrate 12), when the attractive force between the electret 14 and the conductor 16 and the repulsive force between the electrets 14 are equal, the above-mentioned balance is achieved. On the opposing surfaces of the substrates 10, 12,
xz = xw + yz where x + y = 1, z + w = 1
Holds. If y and w are deleted from this equation,
x = z / (3z-1)
It becomes.

  Here, considering that both 0 <x <1 and 0 <z <1 must be satisfied, 0.5 <x <1 and 0.5 <z <1. For example, when x = z, x = z = 2/3. Therefore, it can be seen that the area of the electret 14 and the conductor 16 is not evenly divided, that is, has different values on at least one of the substrates 10 and 12.

  In FIG. 1A, there are eight electrets 14 and four conductors 16 on the substrate 10 side, and the areas of the electrets 14 and the conductors 16 are different values.

  Next, when the substrate 10 is moved in the direction of the arrow A from the state of FIG. 1A to the state of FIG. 1B, the electret is formed on the substrate 10 side in the portion where the substrates 10 and 12 overlap. There are seven 14 and four conductors 16, and five electrets 14 and six conductors 16 on the substrate 12 side. Accordingly, the areas of the electret 14 and the conductor 16 in the two substrates 10 and 12 have different values.

  According to the above configuration, the repulsive force and the suction force between the substrate 10 and the substrate 12 can be substantially balanced, and the distance between the substrates 10 and 12 can be properly maintained. In addition, between the board | substrate 10 and the board | substrate 12, it can be set as gas, liquid, or a vacuum state, such as air, A friction between the board | substrates 10 and 12 can be eliminated, and a relative motion can be performed easily.

  2A and 2B show an arrangement example of the electret 14 and the conductor 16. 2A is an arrangement example on the substrate 10, and FIG. 2B is an arrangement example on the substrate 12, and is a plan view on the side where the electret 14 and the conductor 16 are formed. It is.

  2A and 2B, the electret 14 and the conductor 16 are formed in a strip shape (a rectangular thin plate), and the conductor 16 is distinguished from the electret 14 by hatching. In the substrate 10 shown in FIG. 2A, eight electrets 14 and four conductors 16 are formed. Further, in the substrate 12 shown in FIG. 2B, six electrets 14 and six conductors 16 are alternately formed. In the electrostatic induction conversion element according to the present embodiment, the substrate 10 shown in FIG. 2A is turned upside down so as to face the substrate 12 shown in FIG. 2B. Thereby, the electrostatic induction type conversion element shown in FIG.

  FIGS. 3A and 3B show other arrangement examples of the electret 14 and the conductor 16. 3A is an arrangement example on the substrate 10, and FIG. 3B is an arrangement example on the substrate 12, and is a plan view on the side where the electret 14 and the conductor 16 are formed. It is.

  3A and 3B, the electrets 14 and the conductors 16 are formed in a square shape and are arranged in a grid pattern. Also in this embodiment, the conductor 16 is hatched to distinguish it from the electret 14. In the substrate 10 shown in FIG. 3A, 24 electrets 14 and 12 conductors 16 are formed. Moreover, in the board | substrate 12 shown by FIG.3 (b), the electret 14 and the conductor 16 are formed in 18 pieces each in the checkered pattern shape.

  In the electrostatic induction conversion element according to the present embodiment, the substrate 10 shown in FIG. 3A is turned over in the vertical direction or the horizontal direction in the drawing so as to face the substrate 12 shown in FIG. . As a result, there are 18 combinations in which the electrets 14 and the conductors 16 face each other, and 12 combinations in which the electrets 14 face each other. Note that there are six combinations in which the conductors 16 face each other and no attractive force or repulsive force occurs.

  According to the arrangement examples shown in FIGS. 2A and 2B and FIGS. 3A and 3B, the attractive force between the electret 14 and the conductor 16 and the repulsive force between the electrets 14 are obtained. Can be roughly balanced.

  FIG. 4 shows still another arrangement example of the electret 14 and the conductor 16. In FIG. 4, when the substrates 10 and 12 are divided into a plurality of regions (I, II, III...), The combination of the electret 14 and the conductor 16, the combination of the electrets 14 and the combination of the conductors 16 are different. The ratio region is distributed to balance the attractive force and the repulsive force. In the example of FIG. 4, the repulsion state between the electrets 14 is formed in the region I, the suction state between the electret 14 and the conductor 16 is formed in the region II, and the region where the repulsion force is generated and the region where the suction force is generated thereafter. They are formed alternately.

  FIG. 5 shows an application example of the electrostatic induction conversion element according to the present invention. In FIG. 5, the substrate 10 is connected to the housing 22 via a spring 24 and is configured to vibrate relative to the substrate 12.

  According to the above configuration, the substrate 10 moves relative to the substrate 12 when the housing 22 vibrates. If the induced electromotive force generated at this time is taken out from the terminals 18 and 20 shown in FIGS. 1A and 1B, the apparatus shown in FIG. 5 can be used as a generator or a vibrometer. .

  Examples of the insulating material forming the electret 14 described above include PTFE (polytetrafluoroethylene), FEP (tetrafluoroethylene / hexafluoropropylene copolymer), and PFA (tetrafluoroethylene / perfluoro (alkyl vinyl ether)). A copolymer, silicon oxide, a polymer having a fluorine-containing aliphatic ring structure, or a solvent-soluble fluorine-containing resin can be used.

  Here, the polymer having the above-mentioned fluorinated aliphatic ring structure has a fluorinated aliphatic ring structure in the main chain obtained by cyclopolymerizing a fluorinated monomer having two or more polymerizable double bonds. The polymer having is preferred.

  Having a fluorine-containing aliphatic ring structure in the main chain means that at least one carbon atom constituting the aliphatic ring is a carbon atom in the carbon chain constituting the main chain, and the carbon atom constituting the aliphatic ring is It means having a structure in which a fluorine atom or a fluorine-containing group is bonded to at least a part. The fluorine-containing aliphatic ring structure may contain one etheric oxygen atom.

  Polymers having a fluorinated aliphatic ring structure in the main chain obtained by cyclopolymerization of a fluorine-containing monomer having two or more polymerizable double bonds are disclosed in JP-A-63-238111 and JP-A-2003-238111. No. 63-238115, USP 6,936,668 B2, and the like. That is, a cyclized polymer of a fluorine-containing monomer having two or more polymerizable double bonds such as perfluoro (allyl vinyl ether) or perfluoro (butenyl vinyl ether), or having two or more polymerizable double bonds Examples thereof include a copolymer of a fluorine-containing monomer and a radical polymerizable monomer such as tetrafluoroethylene. Alternatively, a monomer having a fluorine-containing aliphatic ring structure such as perfluoro (2,2-dimethyl-1,3-dioxole) and two or more polymerizations such as perfluoro (allyl vinyl ether) or perfluoro (butenyl vinyl ether) It may be a polymer obtained by copolymerizing a fluorine-containing monomer having an ionic double bond.

  Examples of the solvent-soluble fluorine-containing resin include fluorinated perylene, fluorinated polyimide, and fluorinated benzoxazal.

  In addition, when the electret 14 is formed by a method such as spin coating using the polymer having the fluorine-containing aliphatic ring structure as described above, the thickness of the electret 14 can be set to 10 μm or more. The maximum power generation output of the electrostatic induction conversion element using the electret 14 is expressed by the following equation.

  Here, σ is the surface charge density of the electret 14, n is the number of poles, that is, the number of electrets 14, A is the area of the conductor 16, f is the frequency of reciprocation of the conductor 16, d is the thickness of the electret 14, and g is the electret. 14 is the distance between the conductor 16 and ε is the relative permittivity.

  As can be seen from the above equation, the greater the thickness d of the electret 14, the greater the power generation output. In the material conventionally used, the thickness d of the electret 14 could only be about several tens to 10 μm. However, when the polymer having the fluorinated aliphatic ring structure is used, as described above, the electret The thickness d of 14 can be 10 μm or more, and the maximum power generation output of the electrostatic induction conversion element can be increased.

  The polymer having a fluorine-containing aliphatic ring structure in the main chain is commercially available from Asahi Glass Co., Ltd. under the trade name “CYTOP (registered trademark)”. In the present invention, such a known fluorine-containing polymer is used. Can be used. In addition, the dielectric breakdown strength of this CYTOP (registered trademark) is 11 kV / 0.1 mm, for example, higher than the dielectric breakdown strength of 5 kV / 0.1 mm of Teflon (registered trademark) AF which is a conventionally used material. Yes. If the dielectric breakdown strength can be increased, the amount of charge injected into the electret 14 can be increased, and the maximum power generation output of the electrostatic induction conversion element can be further increased. As a result, the power generation amount of the generator and the sensitivity of the sensor can be improved.

It is sectional drawing of the structural example of the electrostatic induction type conversion element concerning this invention. It is a figure which shows the example of arrangement | positioning of an electret and a conductor. It is a figure which shows the other example of arrangement | positioning of an electret and a conductor. It is a figure which shows the further example of arrangement | positioning of an electret and a conductor. It is a figure which shows the application example of the electrostatic induction type conversion element concerning this invention. It is a figure which shows the structural example of the conventional electrostatic actuator.

Explanation of symbols

  10, 12 substrates, 14 electrets, 16 conductors, 18, 20 terminals, 22 housings, 24 springs.

Claims (7)

An electrostatic induction conversion element that converts electrical energy and kinetic energy,
Substrates that face each other and move relatively in a direction parallel to the facing surface;
Electrets and conductors formed mixed on each facing surface of the substrate;
The electret and the conductor are arranged so that a suction force generated by the electret and the conductor facing each other and a repulsive force generated by the electret facing each other are substantially balanced. An electrostatic induction type conversion element.   2. The electrostatic induction conversion element according to claim 1, wherein the total areas of the electret and the conductor are different values on at least one of the substrates.   3. The electrostatic induction conversion element according to claim 1 or 2, wherein the electret and the conductor are formed in a strip shape.   3. The electrostatic induction conversion element according to claim 1, wherein the electrets and the conductors are arranged in a grid pattern.   5. The electrostatic induction conversion element according to claim 1, wherein the electret includes PTFE (polytetrafluoroethylene), FEP (tetrafluoroethylene / hexafluoropropylene copolymer), PFA ( Electrostatic induction conversion comprising a tetrafluoroethylene / perfluoro (alkyl vinyl ether)) copolymer, silicon oxide, a polymer having a fluorine-containing aliphatic ring structure, or a solvent-soluble fluorine-containing resin element.   6. The electrostatic induction conversion element according to claim 5, wherein the polymer having a fluorine-containing aliphatic ring structure is obtained by cyclopolymerizing a fluorine-containing monomer having two or more polymerizable double bonds. An electrostatic induction conversion element comprising a polymer having a fluorine-containing aliphatic ring structure in a chain. 7. The electrostatic induction conversion element according to claim 6, wherein the fluorine-containing aliphatic ring structure contains one or less etheric oxygen atoms.

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