JP5560838B2 - Electrostatic actuator slider and electrostatic actuator - Google Patents

Description

  The present invention relates to an electrostatic actuator moving element and an electrostatic actuator.

  2. Description of the Related Art Conventionally, there has been known an electrostatic actuator including a stator provided with electrodes, and a movable element disposed on the stator and having a resin substrate and a resistor film provided on the resin substrate. It has been.

  In the electrostatic actuator having such a configuration, the resistor film of the moving element includes, for example, a metal oxide-based material such as tin oxide that is said to be stable against changes in humidity, and a binder that binds these materials. Contains.

  In such a mover, if the surface resistance value of the resistor film changes greatly due to changes in humidity, even if the resistor film of the mover is subjected to an electric field from the stator electrode, if the surface resistance value is low, It discharges immediately, and when it is high, it becomes difficult to be charged. That is, there is a problem that the moving element cannot be operated stably.

  Further, a conventional electrostatic actuator is known that uses ATO (Antimony Tin Oxide) and a binder as a material of a resistor film of a moving element (see, for example, Patent Document 1). However, in this conventional electrostatic actuator, ATO is used for the resistor film in the form of conductive particles, that is, granular (particulate), and is in the form of chains (fiber, needle, mesh, Alternatively, ATO (also referred to as a network shape) is not used for the resistor film.

JP-A-2005-237651

  The present invention has been made in consideration of such points, and an object of the present invention is to provide a movable element capable of reducing the influence of humidity change on the operating characteristics of the movable element.

A mover according to one embodiment of the present invention includes:
In the mover disposed on the linear electrode of the stator having a substrate and a plurality of linear electrodes provided independently on the substrate and arranged in parallel to each other,
The moving element has a resin substrate and a resistor film provided on the resin substrate,
The resistor film includes a material composed of at least one of a chain or multilayer plate-like ATO and a carbon nanotube, and a binder that binds the chain or multilayer plate-like ATO or the carbon nanotube,
This is a mover characterized by that.

In the above moving element,
Polyester or polypropylene may be used as the binder.

An electrostatic actuator according to an aspect of the present invention is provided.
A stator having a substrate and a plurality of linear electrodes provided independently on the substrate and arranged in parallel to each other;
A mover disposed on the linear electrode of the stator, and
The moving element has a resin substrate and a resistor film provided on the resin substrate,
The resistor film includes a material composed of at least one of a chain-shaped or multilayer plate-shaped ATO and a carbon nanotube, and a binder that binds the chain-shaped or multilayer plate-shaped ATO or the carbon nanotube.
This is an electrostatic actuator.

In the electrostatic actuator,
As the binder, polyester or polypropylene may be used.

  The mover of the electrostatic actuator according to the present invention includes a resin substrate facing the stator, and a resistor film provided on the resin substrate, and the resistor film is formed in a chain shape (fiber shape, needle Or a multi-layer plate-like ATO, or a carbon nanotube, and a binder.

  Thereby, compared with a prior art, the change of the resistance value of the resistive element film | membrane of a movable element by a humidity change is suppressed. Therefore, the static electricity of the mover charged by the stator electrodes is held for an appropriate time, and the mover operates stably.

  That is, it is possible to reduce the influence of humidity change on the operating characteristics of the mover.

It is a perspective view which shows an example of a structure of the electrostatic actuator by this invention. FIG. 2 is a top view schematically showing the electrostatic actuator shown in FIG. 1. It is sectional drawing which shows the cross section of the electrostatic actuator along the AA line of FIG. It is an observation photograph of a chain-like carbon nanotube. It is an observation photograph of a carbon nanotube (CNT) of a multilayer plate shape. It is a model figure of a multi-layer plate-like carbon nanotube (CNT). It is a wave form diagram which shows an example of the waveform of the signal applied to a linear electrode. It is a figure which shows the relationship between the humidity of the atmosphere where the electrostatic actuator which concerns on this invention was placed, and the relative moving distance with respect to the stator of a moving element. It is a figure which shows the relationship between the humidity of the atmosphere where the electrostatic actuator of the comparative example was placed, and the relative moving distance with respect to the stator of a moving element. It is a figure which shows the time-dependent change of the surface resistance value of the mobile | mover (invention) containing chain | strand-shaped ATO, and the time-dependent change of the surface resistance value of the mobile | mover containing a granular ATO (comparative example). In the electrostatic actuator of a comparative example, it is a figure which shows an example of the relationship between the surface resistance value of the slider which has a resistor film containing a tin oxide, and humidity.

  Embodiments of an electrostatic actuator according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a perspective view showing an example of the configuration of an electrostatic actuator 100 according to the present invention. FIG. 2 is a top view schematically showing the electrostatic actuator 100 shown in FIG. 3 is a cross-sectional view showing a cross section of the electrostatic actuator 100 along the line AA in FIG. For simplicity, the cover film 103 and the sliding structure film 104 are omitted in FIG.

  As shown in FIGS. 1 and 2, the electrostatic actuator 100 is provided independently on the substrate 102 having one surface 102a and the other surface 102b and on one surface 102a of the substrate 102, and is arranged in parallel with each other at equal intervals. A stator 1 having a plurality of linear electrodes 1a to 1d, and a movable element 2 that is movably disposed on the linear electrodes 1a to 1d of the stator 1.

  Signals a to d for driving the mover 2 are input to the 4-wire electrostatic actuator 100 from a drive circuit (not shown). At this time, the signals a to d are respectively applied to the linear electrodes 1a to 1d via the bus lines 101a to 101d, the through-hole wirings 1b2 and 1d2, and the pad electrodes 1b1 and 1d1.

  Hereinafter, the stator 1 will be described in more detail. As described above, the stator 1 includes the substrate 102 and the plurality of linear electrodes 1 a to 1 d having conductivity provided on one surface 102 a of the substrate 102.

  Furthermore, it extends to one side of the plurality of linear electrodes 1a to 1d (left side in FIG. 2) in a direction orthogonal to the plurality of linear electrodes 1a to 1d, and is respectively provided to the linear electrode 1a and the linear electrode 1b. The first bus line 101a and the second bus line 101b to be connected are provided in parallel to each other. Furthermore, it extends in the direction orthogonal to the plurality of linear electrodes 1a to 1d on the other side of the plurality of linear electrodes 1a to 1d (right side in FIG. 2) and is connected to the linear electrodes 1c and 1d, respectively. The third bus line 101c and the fourth bus line 101d are provided in parallel to each other.

  A cover film 103 is provided to cover the plurality of linear electrodes 1 a to 1 d provided on the one surface 102 a of the substrate 102, and a sliding structure film 104 is provided to cover the cover film 103.

  By the way, the substrate 102 has a thickness of, for example, 25 μm. Examples of the material used for the substrate 102 include polyimide, glass epoxy resin, phenol resin, PET (polyethylene terephthalate), PET-G (terephthalic acid-cyclohexanedimethanol-ethylene glycol copolymer), and PEN (polyethylene naphthalate). ), PP (polypropylene), PE (polyethylene), PC (polycarbonate), PA (polyamide), PPS (polyphenylene sulfide), polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, cellulose diacetate, cellulose triacetate, polystyrene System, ABS, polyacrylate, polyethylene, polyurethane, etc. are selected. PEN is particularly preferable because of its high heat resistance and high strength.

  Further, as described above, the plurality of linear electrodes 1a to 1d are independently provided on the one surface 102a of the substrate 102, and are repeatedly arranged in a comb-like shape at equal intervals in parallel with each other. For example, the wiring electrodes 1a to 1d are set to have a wiring pitch of 0.3 mm or less, and the thickness of the linear electrodes 1a to 1d is, for example, ITO (indium tin oxide) as an electrode material on a PET substrate. In the case of forming, the thickness is about 1,500 mm (see FIGS. 2 and 3).

  Further, the two first and second bus lines 101a and 101b each have a band shape, and are provided on one side (left side in FIG. 2) of the linear electrodes 1a to 1d as described above.

  Among these, the first bus line 101a is provided on one surface (upper surface) 102a of the substrate 102, and the first bus line 101a is electrically connected to the linear electrode 1a.

  The second bus line 101b is provided on the other surface (lower surface) 102b of the substrate 102 and is electrically connected to the linear electrode 1b. The substrate 102 is provided with through-hole wiring 1b2 that penetrates the substrate 102 and is connected to the second bus line 101b provided on the other surface 102b of the substrate 102. Further, a pad electrode 1b1 for connecting one side of the linear electrode 1b and the through-hole wiring 1b2 is provided on one surface 102a of the substrate 102.

  As a result, the second bus line 101b is electrically connected to the linear electrode 1b.

  Further, the two third and fourth bus lines 101c and 101d each have a strip shape, and are provided on the other side (right side in FIG. 2) of the linear electrodes 1a to 1d as described above.

  The third bus line 101c is provided on one surface (upper surface) 102a of the substrate 102 and is electrically connected to the linear electrode 1c.

  The fourth bus line 101d is provided on the other surface (lower surface) 102b of the substrate 102 and is electrically connected to the linear electrode 1d. Here, the substrate 102 is provided with a through-hole wiring 1 d 2 that penetrates the substrate 102 and is connected to the fourth bus line 101 d provided on the other surface 102 b of the substrate 102. A pad electrode 1d1 that connects one side of the linear electrode 1d and the through-hole wiring 1d2 is provided on one surface (upper surface) 102a of the substrate 102.

  Thereby, the fourth bus line 101d is electrically connected to the linear electrode 1d.

  Next, the cover film 103 and the sliding structure film 104 of the stator 1 will be described in detail with reference to FIG. As shown in FIG. 3, the cover film 103 is provided on the substrate 102 so as to cover the plurality of linear electrodes 1 a to 1 d. For example, the cover film 103 has a thickness of 12.5 μm. As a material used for the cover film 103, for example, polyimide is selected.

  The sliding structure film 104 is provided on the cover film 103. This sliding structure film 104 has slidability with respect to the lower surface of the moving element 2 (the lower surface of a resin substrate 2a described later). The sliding structure film 104 has a thickness of several nm, for example. For example, silicon is selected as the material used for the sliding structure film 104.

  The distance d from the upper surface of the linear electrodes (driving electrodes) 1a to 1d to the charging surface (lower surface) of the resistor film 2b is set to, for example, 30 μm or more and 150 μm or less.

  Next, the moving element 2 will be described in detail with reference to FIGS. As shown in FIGS. 1 and 2, the mover 2 is disposed on the stator 1. As shown in FIG. 3, the mover 2 includes a resin substrate 2a provided to face the stator 1, and a resistor film 2b provided on the resin substrate 2a.

  Among these, the resin substrate 2 a is disposed so as to face and contact the stator 1. The resin substrate 2a has a thickness of about 50 μm, for example.

  Examples of the material used for the resin substrate 2a include PET (polyethylene terephthalate), PET-G (terephthalic acid-cyclohexanedimethanol-ethylene glycol copolymer), PEN (polyethylene naphthalate), PP (polypropylene), and PE. (Polyethylene), PC (polycarbonate), PA (polyamide), PPS (polyphenylene sulfide), polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, cellulose diacetate, cellulose triacetate, polystyrene, ABS, polyacrylic ester Polyethylene, polyurethane, etc. are selected. In particular, PEN is preferable because of its high heat resistance and high strength.

As described above, the resistor film 2b is provided on the resin substrate 2a, and the resistor film 2b has a thickness of about 1 μm, for example. The resistor film 2b has a surface resistance value in the range of 10 ¹¹ to 10 ¹³ Ω / □, for example.

  Here, FIG. 4 is an observation photograph of chain carbon nanotubes. FIG. 5 is an observation photograph of a carbon nanotube (CNT) in the form of a multilayer plate. FIG. 6 is a model diagram of a multi-walled plate-like carbon nanotube (CNT).

  The resistor film 2b is formed, for example, in a chain shape (also referred to as a fiber shape, a needle shape, a mesh shape, or a network shape) as shown in FIG. 4 or a multilayer plate-like ATO as shown in FIGS. And a material composed of at least one of carbon nanotubes and a binder for bonding these ATO or carbon nanotubes.

  As a binder, a structure can be used with resin with low hygroscopicity, such as polyester or a polypropylene, for example. Thereby, compared with an acrylic resin etc., the change of the surface resistance value by a humidity change becomes small, and the stable operation | movement of a slider can be aimed at.

  Note that it is desirable that the resistor film 2b does not contain an emulsifying agent and a dispersing agent (surfactant) if possible.

  In addition, for example, an evaluation by a transmission electron microscope (TEM) is applied to an evaluation method that the resistor film 2 includes at least one of chain-like or multilayer plate-like ATO and carbon nanotubes. .

  Next, the operation of the present embodiment having the above configuration, that is, the operation of the electrostatic actuator 100 will be described.

  First, as shown in FIG. 2, the signals a to d are input to the electrostatic actuator 100 from a drive circuit (not shown). At this time, the signals a to d are respectively applied to the linear electrodes 1a to 1d via the bus lines 101a to 101d, the through-hole wirings 1b2 and 1d2, and the pad electrodes 1b1 and 1d1.

  Here, FIG. 7 is a waveform diagram showing an example of waveforms of signals a to d applied to the linear electrodes 1 a to 1 d. Although FIG. 7 shows the case where the signals a to d are rectangular waves, the same phase relationship is obtained when the signals a to d are sine waves.

  As shown in FIG. 7, the two signals a and b input to the adjacent linear electrodes 1a and 1b are shifted by a quarter cycle. Similarly, the two signals b and c input to the adjacent linear electrodes 1b and 1c are shifted by a quarter period. Similarly, the two signals c and d input to the adjacent linear electrodes 1c and 1d are shifted by a quarter period.

  Thereby, the signals a and c whose phases are shifted by a half cycle are input to the linear electrode 1a and the linear electrode 1c, respectively. In addition, signals b and d whose phases are shifted by a half cycle are input to the linear electrode 1b and the linear electrode 1d, respectively.

  In this case, the resistor film 2b of the mover 2 is charged according to the signals a to d applied to the linear electrodes 1a to 1d. Then, by changing the voltages of the signals a to d, the mover 2 moves on the stator 1 in a direction perpendicular to the linear electrodes 1a to 1d before the charged portion of the mover 2 is discharged. (FIG. 2).

  In addition, when the surface resistance value of the resistor film is low, the discharge does not move before moving due to the voltage change of the signals a to d, and when the surface resistance value is high, the charging is difficult and the malfunction does not occur.

  Next, the relationship between the moving characteristics of the moving element and the humidity will be examined with reference to FIGS. By examining the relationship between the movement characteristics of the movable element and the humidity, the stability of the movement of the movable element over time can be known. In the examples of FIGS. 8 and 9, the movement distance relative to the stator is measured as the movement characteristic.

  Here, FIG. 8 is a diagram showing the relationship between the humidity of the atmosphere in which the electrostatic actuator according to the present invention is placed and the relative movement distance of the mover relative to the stator. FIG. 9 is a diagram showing the relationship between the humidity of the atmosphere where the conventional electrostatic actuator as a comparative example is placed and the relative movement distance of the mover relative to the stator.

  8 and 9, the movement distance on the vertical axis is normalized with the relative movement distance (40 mm) relative to the stator of the mover as 100. In addition, as an evaluation sample, a mover having a 10 cm × 10 cm rectangular shape formed by forming a 0.7 ± 0.3 μm resistor film on a 50 μm thick substrate (PET) is used. In the example of FIG. 8, a chain ATO is used for the resistor film of the mover. In the comparative example of FIG. 9, granular ATO is used for the resistor film of the mover.

  As shown in FIGS. 8 and 9, when the humidity is in the range of 20% to 50%, the movable body (the present invention) having a resistor film containing chain ATO and the resistor film containing granular ATO are included. Similarly to the movable element (comparative example), the movable distance can be moved.

  When the humidity exceeds 50%, both of them deteriorate in the movement characteristics. However, the moving element (the present invention) having a resistor film containing chain ATO is less deteriorated in moving characteristics than the moving element (comparative example) having a resistor film containing granular ATO.

  As described above, the movable element having the resistor film containing chain ATO (the present invention) is more affected by the humidity change on the movement characteristic than the movable element having the resistor film containing granular ATO (comparative example). It is considered small.

  Next, the change with time of the surface resistance value of the slider will be examined with reference to FIG. By examining the change over time in the surface resistance value of the slider, the stability of the operation of the slider over time can be known. FIG. 10 is a diagram showing the change over time of the surface resistance value of the mover containing the chain-like ATO (the present invention) and the change over time of the surface resistance value of the mover containing the granular ATO (comparative example). In FIG. 10, as an evaluation sample, a mover having a rectangular shape of 10 cm × 10 cm, in which a 0.7 ± 0.3 μm resistor film is formed on a 100 μm thick substrate (PET). Used. The storage method is actually left in the warehouse (humidity about 40-80%, temperature 20-35 ° C), and the humidity during measurement is 50 ± 5%, and the temperature is 22 ± 1 ° C. .

As shown in FIG. 10, the threshold value of percolation is about 10 ¹² Ω / □ for both the chain shape and the granular shape, but the change is large. In particular, the surface resistance value of the moving element (comparative example) containing granular ATO is an evaluation sample. In about 8 weeks from the formation of the film, it greatly decreases (changes to about 1/10) from 2.8 × 10 ¹² Ω / □ to 2.6 × 10 ¹¹ Ω / □. That is, a resistor film containing granular ATO is required in a relatively large amount in order to obtain electrical conduction such as formation of clusters of particles, and the gap between the particles forming the resistor film is narrow, so that moisture and foreign matter in the environment. The surface resistance value is greatly reduced because it is easily affected by the adhesion.

On the other hand, the surface resistance value of the mover (invention) containing chain-like ATO is from 1.3 × 10 ¹² Ω / □ to 2.8 × 10 ¹² Ω / □ in about 8 weeks from the formation of the evaluation sample. It changes (changes about twice) (FIG. 10). This is considered to be because the chain is long and easy to conduct, and the conduction is obtained with a relatively small amount, so that the gap in the resistor film is wide and hardly affected by moisture and foreign matters in the environment.
As described above, the surface resistance value (resistance value of the resistor film) of the moving element (comparative example) containing granular ATO greatly changes with time. When the resistance value of the resistor film is lowered, it becomes easy to discharge even if the resistor film of the mover is charged to the linear electrode, and the mover cannot be operated stably. Furthermore, when the surface resistance value (resistance value of the resistor film) changes greatly, it is difficult to set the surface resistance value of the resistor film to a target value, and the yield decreases.

  On the other hand, the moving element including the chain-like ATO (the present invention) is unlikely to change in characteristics or change due to moisture or foreign matter over time, so that the change in surface resistance value is small and the moving element is stably operated. be able to.

In addition, by adopting chain-like ATO as a material for the resistor film, desired characteristics of the resistor film (for example, a surface resistance value of about 10 ¹² Ω / □) can be obtained with a small amount of ATO. The manufacturing cost of the electrostatic actuator can be reduced. Furthermore, the transparency can be higher and the design is good.

  On the other hand, when the resistor film of the mover includes carbon nanotubes, the change in the surface resistance value with respect to a change in humidity or a change with time is small as compared with the prior art. Therefore, also in this case, a stable operation of the mover can be achieved. The carbon nanotubes have a long structure like the chain ATO and have a wide gap in the resistor film, so that the influence of moisture and foreign matters in the environment is small.

  Note that particulate ATO and carbon nanotubes are prone to agglomerate and have a problem that they do not disperse even when agitated, resulting in a problem that the surface resistance value is lowered or in-plane variation of the surface resistance value is increased. When the surface resistance value decreases due to agglomeration, even if an attempt is made to adjust by adding a small amount of binder, the adjustment becomes difficult because the surface resistance value suddenly increases.

  On the other hand, in the case of a chain, it is difficult to agglomerate, so that even when stored for a long period of time, the surface resistance value can be easily adjusted to a predetermined value by stirring and the in-plane variation is small. In the particulate form, it became unusable due to aggregation in about 1 month, but in the chain form, it could be used if it was stirred even after 3 months.

  Next, the characteristics of the mover of the electrostatic actuator according to the present invention will be described in comparison with a general mover having a resistor film containing tin oxide.

  Here, FIG. 11 is a diagram illustrating the relationship between the surface resistance value of the movable element having the resistor film containing tin oxide and the humidity in the electrostatic actuator of the comparative example. As an evaluation sample, a mover constituted by forming a 0.7 ± 0.3 μm resistor film on a 100 μm thick substrate (PET) is used.

  As shown in FIG. 11, when the humidity increases from 50% to 80%, the surface resistance value of the resistor film changes from 1/20 to 1/30. As described above, when the resistance value of the resistor film changes, even if the resistor film and the linear electrode of the mover are charged, they are easily discharged, and the mover cannot be operated stably. Furthermore, when the surface resistance value (resistance value of the resistor film) changes greatly, it is difficult to set the surface resistance value of the resistor film to a target value, and the yield decreases.

  As compared with the electrostatic actuator moving element as the comparative example shown in FIG. 11, the moving element of the electrostatic actuator according to the present invention includes a resin substrate provided opposite to the stator and a resin as described above. A resistor film provided on a substrate, and the resistor film is an ATO in a chain shape (also referred to as a fiber shape, a needle shape, a mesh shape, or a network shape) or a multilayer plate shape, or And a material comprising any one of carbon nanotubes and a binder.

  Thereby, the change of the resistance value of the resistor film of the mover due to the humidity change is suppressed, and the mover can be operated stably.

Furthermore, by adopting carbon nanotubes as a material for the resistor film, desired characteristics of the resistor film (for example, a surface resistance value of about 10 ¹² Ω / □) can be obtained with a small amount of carbon. The manufacturing cost of the electric actuator can be reduced. Furthermore, the transparency can be higher and the design is good. In addition, since the carbon content in the resistor film can be reduced, it is considered that the influence on the resistance value is small even if moisture enters the gap in the resistor film.

  In addition, as described above, in any case where chain-like or multi-layer plate-like ATO and carbon nanotubes are employed, since the binder uses a resin having a low hygroscopic property such as polyester or polypropylene, the humidity change is further improved. The influence can be reduced.

  As described above, according to the slider of the electrostatic actuator according to the present embodiment, it is possible to reduce the influence of humidity change on the operating characteristics of the slider.

DESCRIPTION OF SYMBOLS 1 Stator 1a-1d Linear electrode 1b1, 1d1 Pad electrode 1b2, 1d2 Through-hole wiring 2 Mover 2a Resin substrate 2b Resistor film | membrane 100 Electrostatic actuator 101a 1st bus line 101b 2nd bus line 101c 3rd Bus line 101d Fourth bus line 102 Substrate 103 Cover film 104 Sliding structure film a to d Signal

Claims (4)

In the mover disposed on the linear electrode of the stator having a substrate and a plurality of linear electrodes provided independently on the substrate and arranged in parallel to each other,
The moving element has a resin substrate and a resistor film provided on the resin substrate,
The resistor film includes a material composed of a chain-like or multilayer plate-like ATO (Antimony-Tin-Oxide) and a binder that joins the chain-like or multilayer plate-like ATO.
A mover characterized by that.   The mover according to claim 1, wherein polyester or polypropylene is used as the binder. A stator having a substrate and a plurality of linear electrodes provided independently on the substrate and arranged in parallel to each other;
A mover disposed on the linear electrode of the stator, and
The moving element has a resin substrate and a resistor film provided on the resin substrate,
The resistor film includes a material including a chain-like or multilayer plate-like ATO (Antimony-Tin-Oxide) and a binder that couples the chain-like or multilayer plate-like ATO.
An electrostatic actuator characterized by that.   The electrostatic actuator according to claim 3, wherein polyester or polypropylene is used as the binder.