JP5844741B2 - Electrostatic induction type electromechanical transducer - Google Patents

Description

  The present invention relates to an electrostatic induction type electromechanical transducer.

  As this type of device, one using an electret (injecting a charge into an insulating material such as a synthetic resin) is known (for example, JP-A-58-6118, JP-A-2001-177899, (See JP 2006-180450 A, JP 2007-298297 A, JP 2010-136598 A, etc.). In order to improve the performance in such devices, it is necessary to increase the charge density in the electret.

  In this regard, polymer electrets (surfaces of polymer materials) disclosed in JP-A-58-6118, JP-A-2001-177899, JP-A-2006-180450, and JP-A-2010-136598 In a configuration using a device in which charges are injected in the vicinity, there is a limit with respect to an increase in charge density. In addition, such a configuration has a problem that heat resistance is low and a problem that the charge density deteriorates with time.

  On the other hand, in the configuration using the ferroelectric electret (the one obtained by subjecting the ferroelectric film to polarization), which is disclosed in Japanese Patent Application Laid-Open No. 2007-298297, it is higher than the configuration using the polymer electret. Charge density and heat resistance are obtained. However, even in such a configuration, depolarization occurs with time in the ferroelectric electret, so that it is difficult to stably maintain the polarization state for a long period of time.

  The present invention has been made to solve such problems. That is, the present invention is to provide an electrostatic induction type electromechanical transducer using electrets having more excellent durability.

<Configuration>
The electrostatic induction electromechanical transducer of the present invention includes an electret made of a ferroelectric film (for example, lead zirconate titanate or lithium niobate). Specifically, for example, the electrostatic induction type electromechanical transducer of the present invention includes the electret, a counter substrate, and a first region counter electrode. The counter substrate is disposed so as to face the main surface of the electret, and is provided to be movable relative to the electret. Specifically, for example, the counter substrate is provided to be movable relative to the electret along the main surface direction.

  Here, the “main surface” in the electret is a surface orthogonal to the thickness direction of the electret which is a film made of a ferroelectric material (the direction defining the thickness of the film). The direction parallel to the “main surface” of the electret is hereinafter referred to as “main surface direction”. The “film” may also be referred to as “thin film” or “thin plate”.

  The first region counter electrode is a conductive film, and is provided corresponding to the first region on the surface of the counter substrate that faces the main surface. Note that a second region counter electrode may be provided on the surface of the counter substrate facing the main surface so as to correspond to the second region. The second region counter electrode is a conductive film, and is provided at a position different from the first region counter electrode so as not to be electrically connected to the first region counter electrode.

  The feature of the present invention resides in that the electrostatic induction type electromechanical transducer has the following configuration.

  In the present invention, the electret has a first region and a second region. The first region is a region in which the polarization direction along the thickness direction is the first direction. The second region is a region in which the polarization direction along the thickness direction is a second direction opposite to the first direction. Specifically, an angle formed by the polarization direction and the thickness direction is −45 to +45 degrees. Typically, the first region is polarized in the first direction parallel to the thickness direction, and the second region is in a second direction opposite to the first direction. Polarized.

  The electret is configured such that the first region and the second region are adjacent to each other along the principal surface direction. That is, in the electret of the present invention, a plurality of the first regions and a plurality of the second regions are provided so that the polarization direction is periodically reversed along the main surface direction. Specifically, for example, the plurality of first regions and the plurality of second regions may be provided so that the inversion period of the polarization direction is 3 to 200 μm.

  The electrostatic induction type electromechanical transducer of the present invention is a polymer film formed on the main surface so as to be in close contact with the main surface of the electret on the side facing the first region counter electrode. Further, a coating layer may be further provided. The coating layer may include, for example, a first coating layer provided on the main surface side of the electret, and a second coating layer that is more elastically deformed than the first coating layer.

  In this case, the second coating layer is provided on the first region counter electrode side and is formed on the first coating layer so as to be in close contact with the first coating layer. Specifically, for example, the second coating layer has a Young's modulus of 0.01 to 5 GPa. Alternatively, the first coating layer has a dense structure, and the second coating layer has voids. In this case, the porosity of the second coating layer is preferably 10 to 90%.

  The electrostatic induction type electromechanical transducer of the present invention may further include a coating layer that is a polymer film provided on the counter substrate side so as to cover the first region counter electrode.

<Action and effect>
As described above, in the ferroelectric electret disclosed in Japanese Patent Application Laid-Open No. 2007-298297, the polarization process is simply performed uniformly, and the same polarity on the same side of the pair of main surfaces. Charge concentrates. For this reason, in such a configuration, the polarization structure becomes unstable due to repulsion between charges, and depolarization occurs.

  On the other hand, in the electret in the electrostatic induction type electromechanical transducer according to the present invention, since the positive and negative charges are alternated in each adjacent region, the polarization state can be stably maintained for a long time. . Therefore, according to the present invention, it is possible to provide an electrostatic induction type electromechanical transducer using electrets that has more excellent durability.

It is sectional drawing which shows schematic structure of one Embodiment of the electrostatic induction type | mold electromechanical conversion element of this invention. It is a principal part enlarged view in other embodiment (modification) of the electrostatic induction type electromechanical transducer of this invention. It is sectional drawing which shows schematic structure of other embodiment (modification) of the electrostatic induction type | mold electromechanical conversion element of this invention. It is sectional drawing which shows schematic structure of other embodiment (modification) of the electrostatic induction type | mold electromechanical conversion element of this invention. It is sectional drawing which shows schematic structure of other embodiment (modification) of the electrostatic induction type | mold electromechanical conversion element of this invention.

  Hereinafter, preferred embodiments of the present invention will be described using examples and comparative examples. In addition, the description about the following embodiment is specific to the extent possible, merely an example of the embodiment of the present invention in order to satisfy the description requirement (description requirement / practicability requirement) of the specification required by law. It is only what is described in.

  Therefore, as will be described later, it is quite natural that the present invention is not limited to the specific configurations of the embodiments and examples described below. Examples of various modifications that can be made to the present embodiment and examples (modifications) are inserted during the description of the embodiment, so that understanding of the description of the consistent embodiment is hindered. It is mainly listed at the end.

<Configuration>
FIG. 1 is a cross-sectional view showing a schematic configuration of an embodiment of the electrostatic induction type electromechanical transducer of the present invention. Referring to FIG. 1, the electrostatic induction type electromechanical transducer 1 of the present embodiment includes an electret support substrate 2, a back electrode 3, an electret 4, a coating layer 5, a counter substrate 6, and a first region facing. And an electrode 7.

  The back electrode 3 is a uniform conductive film, and is formed on one surface (the upper surface in the drawing) of the electret support substrate 2. The electret 4 is a ferroelectric (for example, lead zirconate titanate or lithium niobate) film, and is joined to the back electrode 3. That is, the electret support substrate 2, the back electrode 3, and the electret 4 are stacked in this order in the thickness direction (z-axis direction in the figure) orthogonal to the main surface MS of the electret 4 and provided so as to be in close contact with each other. It has been. The electret 4 is supported on the above-described one surface of the electret support substrate 2 via the back electrode 3.

  The electret 4 has a first region 41 and a second region 42. The first region 41 and the second region 42 are polarized so that the components in the thickness direction of the polarization direction are opposite to each other. Specifically, in the present embodiment, the first region 41 is polarized in one direction (z-axis positive direction in the drawing) parallel to the thickness direction. On the other hand, the second region 42 is polarized in another direction (z-axis negative direction in the drawing) parallel to the thickness direction. That is, the first region 41 and the second region 42 are provided such that the polarization direction is periodically reversed at a predetermined cycle (specifically, 3 to 200 μm).

  In the present embodiment, the first region 41 and the second region 42 are alternately arranged in one direction parallel to the main surface MS (in the figure, the x-axis direction: hereinafter referred to as “main surface direction”). Has been. The first region 41 and the second region 42 are each parallel to the main surface MS and perpendicular to the above-described main surface direction (in the figure, the y-axis direction: hereinafter referred to as “sub-main surface direction”). Is provided so as to have a longitudinal direction.

  The coating layer 5 is a polymer film, and is formed on the main surface MS so as to be in close contact with the main surface MS of the electret 4. In the present embodiment, the coating layer 5 is formed so that the Young's modulus is 0.01 to 5 GPa.

  The counter substrate 6 is disposed so as to face the main surface MS of the electret 4 with the coating layer 5 interposed therebetween. In the present embodiment, the counter substrate 6 is obtained by laminating the electret support substrate 2, the back electrode 3, the electret 4 and the coating layer 5 in this order in the thickness direction (hereinafter, simply referred to as “electret laminate”). ) With respect to the aforementioned main surface direction (x-axis positive direction and negative direction in the figure).

  The first region counter electrode 7 is a comb-like electrode pattern having a planar shape in which one ends of a plurality of linear electrodes in the longitudinal direction are coupled to each other, and is a surface BS facing the above-described electret laminate on the counter substrate 6. Formed on top. Each of the plurality of linear electrodes has a longitudinal direction in the sub-main surface direction described above, and corresponds to the first region 41 (a position facing the first region 41 with the coating layer 5 interposed therebetween). ) Only. In other words, the plurality of first region counter electrodes 7 includes a period of polarization inversion along the principal surface direction (x-axis direction in the drawing) of the electret 4, that is, the first region 41 and the second region along the principal surface direction. Are arranged along the principal surface direction at a period that coincides with the arrangement period of the regions 42.

  As described above, the electrostatic induction type electromechanical transducer 1 according to this embodiment has the fluctuation of the charge induced in the first region counter electrode 7 with the relative movement of the electret 4 and the counter substrate 6 in the main surface direction. Thus, the mechanical energy of the relative movement is converted into electric energy.

<Specific example of manufacturing method>
Hereinafter, a specific example of the manufacturing method of the electrostatic induction type electromechanical transducer 1 of the present embodiment will be described in detail.

A uniform platinum electrode film is formed on a flat-plate electret support substrate made of ZrO ₂ stabilized with Y ₂ O ₃ by screen printing, and the electret support substrate and the platinum electrode film are subjected to heat treatment at 1300 ° C. for 2 hours. And integrated. Next, on the platinum electrode film described above, a lead zirconate titanate powder, a dispersion medium, a plasticizer, and a dispersant are mixed to form a paste, and the film thickness after drying is determined by screen printing. The film was formed to 75 μm.

  In this way, a film obtained by forming (screen printing) a lead zirconate titanate powder paste on an electret support substrate was heat-treated (fired) at 1250 ° C. for 5 hours to obtain a sintered film having a thickness of 50 μm. During this heat treatment, lead zirconate titanate powder was allowed to coexist in the atmosphere.

On the lead zirconate titanate film fixed on the electret support substrate by the above heat treatment, a uniform electrode film (thickness 1000 Å) for polarization treatment made of tantalum was formed. The substrate after electrode formation was immersed in insulating oil (150 ° C.) and subjected to polarization treatment with an electric field strength of about 3 kV / mm (coercive electric field). The uniform electrode after the polarization treatment was removed by acid treatment, and then a comb-shaped electrode film (thickness 1000 angstrom, electrode period 14 μm (main surface direction width 7 μm, main surface direction electrode spacing 7 μm)) was patterned. The patterned material was immersed in insulating oil (150 ° C.), and a polarization treatment was performed by applying a rectangular pulse voltage having a width of about 1 msec with an electric field strength of about 3 kV / mm (coercive electric field). The number of pulses applied depends on the area of the comb electrode pattern. For example, when it is 20 mm ² , 20000 pulses were suitable.

  After the polarization treatment, the comb electrode for polarization treatment was removed by acid treatment. Thereafter, a polyimide film having a Young's modulus of 0.05 Gpa and a thickness of 50 μm was laminated on the lead zirconate titanate film (the surface from which the comb electrode for polarization treatment was removed by acid treatment) to obtain the above laminate. . The obtained laminate was heated to 400 ° C. to perform a charge removal process for removing surface charges.

  On a counter substrate made of a polyimide film, a comb-shaped counter electrode (width in the main surface direction: 6 μm, electrode interval in the main surface direction: 8 μm) was formed by sputtering. By combining the obtained counter substrate with the counter electrode with the above-described laminate so that the electrode portion overlaps the region polarized in the z-axis positive direction (see FIG. 1) in the lead zirconate titanate film, electrostatic induction A mold electromechanical transducer was obtained.

<Operation / Effects of Configuration of Embodiment>
In the electrostatic induction type electromechanical transducer element 1 of this embodiment having such a configuration, the relative movement (reciprocal movement) of the electret 4 and the counter substrate 6 in the main surface direction (x-axis positive direction and negative direction in the figure). Accordingly, the mechanical energy of the relative movement is converted into electric energy by the fluctuation of the charge induced in the first region counter electrode 7 (see JP 2010-136598 A, etc.).

  In this regard, in the electrostatic induction type electromechanical transducer 1 of the present embodiment, the first regions 41 and the second regions 42 whose polarization directions are reversed are arranged alternately along the main surface direction. For this reason, in the main surface MS, positive and negative charges are alternated for each adjacent region. Thereby, it becomes possible to hold | maintain the polarization state of the electret 4 stably for a long period of time. Therefore, according to the configuration of the present embodiment, it is possible to achieve better durability.

  From this point of view, if the arrangement period of the first region 41 and the second region 42 is too large, the size of the first region 41 or the second region 42 in the main surface direction (x-axis direction in the drawing) is reduced. Since it becomes too large, the effect of stabilizing the polarization structure is reduced. On the other hand, a configuration in which the arrangement period of the first region 41 and the second region 42 is too small is difficult to produce stably (industrially). Therefore, the inversion period of the polarization direction, that is, the arrangement period of the first region 41 and the second region 42 is preferably 3 to 200 μm.

  Moreover, in the electrostatic induction type electromechanical transducer 1 of the present embodiment, the neutralized coating layer 5 is provided between the main surface MS of the electret 4 and the first region counter electrode 7. Thereby, the adhesion of foreign matter on the main surface MS is suppressed as much as possible.

  Further, since the Young's modulus of the coating layer 5 is relatively low, even when the coating layer 5 and the first region counter electrode 7 are brought into close contact with each other, the main surface direction (in the drawing) of the electret 4 and the counter substrate 6 The relative movement in the x-axis positive direction and negative direction) is performed well. Therefore, the gap between the main surface MS of the electret 4 and the first region counter electrode 7 is favorably managed by bringing the coating layer 5 and the first region counter electrode 7 into close contact with each other. Therefore, according to such a configuration, a stable power generation operation (mechanical electrical conversion operation) can be performed.

  From this point of view, if the Young's modulus of the coating layer 5 is too high, when the coating layer 5 and the first region counter electrode 7 are brought into close contact with each other, shear deformation of the coating layer 5 hardly occurs. Relative movement in the main surface direction (the x-axis positive direction and negative direction in the figure) with the counter substrate 6 is prevented. On the other hand, if the Young's modulus of the coating layer 5 is too low, the coating layer 5 is too soft and the management of the gap between the main surface MS of the electret 4 and the first region counter electrode 7 cannot be performed well. Therefore, the Young's modulus of the coating layer 5 is preferably 0.01 to 5 GPa.

<List of examples of modification>
It should be noted that the above-described embodiments and specific examples are merely examples of the realization of the present invention that the applicant considered to be the best at the time of filing of the present application, as described above. The invention should not be limited at all by the above-described embodiments and specific examples. Therefore, it goes without saying that various modifications can be made to the above-described embodiments and specific examples without departing from the essential part of the present invention.

  Hereinafter, some modifications will be exemplified. In the following description of the modification, components having the same configurations and functions as the components in the above-described embodiment are given the same name and the same reference numerals in this modification. And about description of the said component, description in the above-mentioned embodiment shall be used suitably in the range which is not inconsistent.

  However, it goes without saying that the modified examples are not limited to the following. The limited interpretation of the present invention based on the description of the above-described embodiment and the following modifications unfairly harms the interests of the applicant (especially rushing the application under the principle of prior application), but improperly imitates the imitator. It is beneficial and not allowed.

  It goes without saying that the configuration of the above-described embodiment and the configuration described in each of the following modifications can be combined in an appropriate manner within a technically consistent range.

  The present invention is not limited to the specific configurations and materials described above. That is, for example, the present invention is not limited to a power generation element (a mechanical / electrical conversion element that generates power by environmental vibration) as in the above-described embodiment, and can be used for a microphone, various sensors, and the like (in this case, an electrode or the like) The shape and arrangement are appropriately changed.) The vibration (relative movement) direction may also be the thickness direction. Furthermore, the electret of the present invention is not limited to lead zirconate titanate (PZT), but is a curie such as lithium niobate, barium titanate, lead titanate, lead metaniobate, bismuth tungstate, bismuth lanthanum titanium oxide, etc. Any ferroelectric material having a temperature may be used.

  Referring to FIG. 1, the first region 41 and the second region 42 may have the same or different widths in the principal surface direction (x-axis direction in the figure). Further, the first region 41 and the second region 42 do not have to be so-called “striped” in plan view as in the above-described embodiment. Specifically, for example, a so-called “checkered pattern” may be used in a plan view. Specifically, the first region 41 and the second region 42 having a substantially rectangular shape (typically a substantially square shape) in plan view may be alternately arranged two-dimensionally.

  The polarization direction may not be parallel to the thickness direction. That is, the angle α [°] formed between the polarization direction in the first region 41 and the positive z-axis direction is −45 ≦ α ≦ + 45, and is formed between the polarization direction in the second region 42 and the negative z-axis direction. The angle β may be such that [°] is −45 ≦ β ≦ + 45 (in this case, the absolute value of α may be the same as or different from the absolute value of β).

  As the coating layer 5, in addition to polyimide, polyamide, polyamideimide, polyetherimide, polyethersulfone, polysulfone, polyacetal, polyphenylene oxide, polyetheretherketone, PTFE, CYTOP (registered trademark), Teflon (registered trademark), It is possible to use organic materials such as It is also possible to use inorganic materials such as low dielectric constant glass, aluminum oxide, zirconium oxide, titanium oxide, and silica alumina.

  The present invention is not limited to the specific manufacturing method described above. That is, for example, as the electret 4, it is possible to use a single crystal wafer, a film formed by the AD method, instead of a sheet molded body fired (ceramic film) as in the above-described embodiment. .

  In this case, specifically, a (001) cut substrate made of lead zirconate titanate single crystal and having a thickness of 500 μm is prepared, and a comb-shaped electrode film (thickness 1000 Å, electrode made of tantalum on the (001) plane thereof. While patterning a period of 7 μm (main surface direction width 3.5 μm, main surface direction electrode spacing 3.5 μm), the (00-1) surface (opposite surface) is a uniform electrode film (thickness) made of tantalum 1000 angstroms). Thereafter, a polarization process or the like is performed in the same manner as in the specific example described above. In this case, the electret support substrate 2 in FIG. 1 can be omitted.

  In the case of using a film formed by the AD method, specifically, an AD film having a thickness of 20 μm, which is formed by injecting lead zirconate titanate having a particle diameter of about 1 μm onto a substrate at a high speed, is prepared. Polarization processing or the like is performed as in the specific example. The AD film may be heat-treated for the purpose of improving crystallinity. A film formed by the AD method is denser and has a smaller primary particle diameter than a film formed by screen printing, and therefore, the insulating property can be increased and the durability can be increased.

  As the comb electrode for polarization treatment, flake graphite powder patterned by, for example, screen printing can be used. By forming the flake-shaped graphite on the ferroelectric film in a lying state, the adhesion strength can be lowered while lowering the contact resistance, so it can be easily removed by blowing off after the polarization treatment. it can.

  The method for forming the coating layer 5 is not only film adhesion as in the above-described embodiment, but also screen printing, bar coating, spin coating, sol-gel, sputtering, CVD, thermal spraying, dipping, air gun coating Etc. can be used.

  In the above specific example, the static elimination treatment is performed by heat treatment up to the depolarization temperature near the Curie point. However, rather than eliminating the polarization state completely (depolarization), the state where the polarization remains to some extent remains. It is preferable to set it in terms of increasing recovery of the polarization state after the temperature is lowered.

  In the specific example described above, the static elimination treatment is performed by heat treatment up to the depolarization temperature near the Curie point, but the present invention is not limited to this. Specifically, for example, the charge removal process may be performed by an acid etching process or the like. Further, it may be performed by ion shower irradiation or the like.

  FIG. 2 is an enlarged view of a main part in another embodiment (modification) of the electrostatic induction type electromechanical transducer of the present invention. Referring to FIG. 2, in the present embodiment, the coating layer 5 includes a first coating layer 51 and a second coating layer 52. The first coating layer 51 is provided on the main surface MS side. The second coating layer 52 is formed on the first coating layer 51 so as to be in close contact with the first coating layer 51.

  The first coating layer 51 has a dense structure in order to protect the main surface MS of the electret 4. On the other hand, the second coating layer 52 is formed so as to have a Young's modulus of 0.01 to 5 GPa by having a large number of voids V so that the porosity is 10 to 90%. The first coating layer 51 and the second coating layer 52 can be formed by a screen printing method, a bar coating method, a spin coating method, a sol-gel method, a sputtering method, a CVD method, thermal spraying, as well as film adhesion as in the above-described embodiment. It is possible to use a method, a dipping method, an air gun coating, or the like.

  If the porosity of the second coating layer 52 is too low, the Young's modulus of the coating layer 5 becomes too high. Therefore, when the coating layer 5 and the first region counter electrode 7 are brought into close contact with each other, the coating layer 5 is sheared. Deformation hardly occurs, and relative movement of the electret 4 and the counter substrate 6 in the main surface direction is hindered. On the other hand, if the porosity of the coating layer 5 is too high, the coating layer 5 becomes too low in Young's modulus (too soft), so that the management of the gap between the main surface MS of the electret 4 and the first region counter electrode 7 can be controlled. It will not work well. Therefore, the porosity of the second coating layer 52 is preferably 10 to 90%.

  FIG. 3 is a cross-sectional view showing a schematic configuration of still another embodiment (modification) of the electrostatic induction type electromechanical transducer of the present invention. Referring to FIG. 3, the counter substrate 6 may be provided with a second region counter electrode 8 facing the second region 42 in addition to the first region counter electrode 7 facing the first region 41. Good. According to such a configuration, not only the first region 41 but also the second region 42 contributes to mechanical / electrical energy conversion, so that the energy conversion efficiency can be further improved.

  FIG. 4 is a cross-sectional view showing a schematic configuration of still another embodiment (modification) of the electrostatic induction type electromechanical transducer of the present invention. Referring to FIG. 4, the coating layer 5 may be provided on the counter substrate 6 side. Specifically, the coating layer 5 may be provided on the surface BS of the counter substrate 6 so as to cover the counter electrodes (the first region counter electrode 7 and the second region counter electrode 8).

  In this case, as shown in FIG. 4, the coating layer 5 covers the counter electrode and the first coating layer 51 formed on the surface BS of the counter substrate 6 so as to fill a gap between the adjacent counter electrodes. And a second coating layer 52 provided on the first coating layer 51, or a single layer structure as shown in FIG. Also good. In this case, the counter electrode may be only the first region counter electrode 7.

  FIG. 5 is a cross-sectional view showing a schematic configuration of still another embodiment (modification) of the electrostatic induction type electromechanical transducer of the present invention. Referring to FIG. 5, the coating layer 5 may be provided on both the electret 4 side and the counter substrate 6 side. That is, the coating layer 5 in this case includes an electret side coating layer 5a and a counter electrode side coating layer 5b. The electret-side coating layer 5 a is formed on the main surface MS so as to be in close contact with the main surface MS of the electret 4. The counter electrode side coating layer 5b is provided on the surface BS of the counter substrate 6 so as to cover the counter electrodes (the first region counter electrode 7 and the second region counter electrode 8). However, in this case, the electret side coating layer 5a and the counter electrode side coating layer 5b are preferably made of the same material. Or the material which comprises the electret side coating layer 5a and the material which comprises the counter electrode side coating layer 5b may be selected so that it may adjoin on a triboelectric row.

  In this case as well, the electret-side coating layer 5a and / or the counter-electrode-side coating layer 5b are similarly laminated layers (the first coating layer 51 provided in close contact with the electret 4 or the counter substrate 6). And a second coating layer 52 formed thereon. Further, the counter electrode may be only the first region counter electrode 7.

  Other modifications not specifically mentioned are naturally included in the technical scope of the present invention without departing from the essential part of the present invention.

  In addition, in each element constituting the means for solving the problems of the present invention, elements expressed functionally and functionally include the specific structures disclosed in the above-described embodiments and modifications, It includes any structure that can realize this action / function. Furthermore, the contents of the prior application and each publication (including the specification and the drawings) cited in the present specification may be incorporated as appropriate as part of the present specification.

Claims (9)

An electret made of a ferroelectric film ;
An opposing substrate that is disposed so as to face the main surface of the electret and is provided so as to be relatively movable along the main surface direction with respect to the electret;
A first region counter electrode, which is a conductive film provided corresponding to the first region of the electret on a surface of the counter substrate facing the main surface;
An electrostatic induction-type electromechanical transducer with
The electret is
A first region in which a polarization direction along the thickness direction is a first direction; and a second region in which the polarization direction along the thickness direction is a second direction opposite to the first direction. And are configured to be adjacent to each other along a principal surface direction that is a direction parallel to a principal surface that is a surface orthogonal to the thickness direction,
Static induction type electromechanical transducer. The electrostatic induction type electromechanical transducer according to claim 1,
The angle formed by the polarization direction and the thickness direction is −45 to 45 degrees,
Static induction type electromechanical transducer. The electrostatic induction type electromechanical transducer according to claim 1 or 2,
A plurality of the first regions and a plurality of the second regions are provided so that the polarization direction is periodically reversed along the main surface direction.
Static induction type electromechanical transducer. The electrostatic induction type electromechanical transducer according to claim 3,
The inversion structure of the polarization direction is a stripe shape having a period of 3 to 200 μm,
Static induction type electromechanical transducer. In the electrostatic induction type electromechanical transducer according to any one of claims 1 to 4 ,
It further comprises a coating layer, which is a polymer film formed on the main surface so as to be in close contact with the main surface of the electret on the side facing the first region counter electrode,
Static induction type electromechanical transducer. The electrostatic induction type electromechanical transducer according to claim 5 ,
The coating layer is
A first coating layer provided on the main surface side of the electret;
A second coating layer which is formed on the first coating layer so as to be in close contact with the first coating layer and which is provided on the first region counter electrode side and is more elastically deformable than the first coating layer; ,
Characterized by comprising
Static induction type electromechanical transducer. The electrostatic induction type electromechanical transducer according to claim 6 ,
The first coating layer has a dense structure;
The second coating layer has voids,
Static induction type electromechanical transducer. The electrostatic induction type electromechanical transducer according to claim 6 or 7 ,
The second coating layer has a Young's modulus of 0.01 to 5 GPa,
Static induction type electromechanical transducer. In the electrostatic induction type electromechanical transducer according to any one of claims 1 to 4 ,
A coating layer, which is a polymer film provided on the counter substrate side so as to cover the first region counter electrode,
Static induction type electromechanical transducer.

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