Electrostatic electroacoustic transducer

Abstract

Provided is a flexible electrostatic electroacoustic transducer having a pair of opposing conductive layers and a dielectric layer arranged between the pair of opposing conductive layers. The electrostatic electroacoustic transducer further includes a flexible buffer layer arranged on a surface of one or both of the pair of opposing conductive layers opposite from the dielectric layer, and a flexible sealing layer arranged on the surface of the buffer layer opposite from the conductive layer.

Description

Electrostatic electroacoustic transducer

[0001] This disclosure relates to an electrostatic electroacoustic transducer.

[0002] Conventionally, flexible electrostatic electroacoustic transducers are known as one type of acoustic device. Flexible electrostatic electroacoustic transducers generally have a dielectric layer and a pair of conductive layers arranged opposite each other on both sides of the dielectric layer. By applying an electrical signal to the pair of conductive layers, the dielectric layer and the conductive layers vibrate together to generate sound waves. By using thin, flexible materials for the dielectric layer and the conductive layer, the electrostatic electroacoustic transducer as a whole can be made flexible.

[0003] For example, Patent Document 1 describes an electrostatic speaker characterized by comprising: a vibrating membrane made of a thin film member; a conductive, acoustically transparent planar electrode positioned opposite the vibrating membrane; and a buffer member positioned between the vibrating membrane and the planar electrode, formed by including a material that is at least opposite the vibrating membrane in the triboelectric series.

[0004] Japanese Patent Publication No. 2012-182684

[0005] The present disclosure aims to provide a flexible electrostatic electroacoustic transducer that, while having a sealing layer for purposes such as waterproofing and insulation, can generate sound waves with high sound pressure, low noise generation, and excellent sound quality.

[0006] Examples of embodiments of the present disclosure are listed below: [1] A flexible electrostatic electroacoustic transducer having a pair of opposing conductive layers and a dielectric layer disposed between the pair of opposing conductive layers, wherein the electrostatic electroacoustic transducer further comprises: a flexible buffer layer disposed on the surface of one or both of the pair of opposing conductive layers opposite to the dielectric layer; and a flexible sealing layer disposed on the surface of the buffer layer opposite to the conductive layer. [2] The electrostatic electroacoustic transducer according to [1], wherein the buffer layer and the conductive layer are joined, and the peel strength between the buffer layer and the conductive layer is 0.15 N / cm or more. [3] The electrostatic electroacoustic transducer according to [1] or [2], wherein the sealing layer and the buffer layer are joined. [4] The electrostatic electroacoustic transducer according to any one of [1] to [3], wherein the bonding area between each layer is less than 100% with respect to the area where the sealing layer and the buffer layer face each other. [5] The electrostatic electroacoustic transducer according to any one of [1] to [4], wherein the bonding area between each layer is less than 100% based on the area where the buffer layer and the conductive layer face each other. [6] The electrostatic electroacoustic transducer according to any one of [1] to [5], wherein the buffer layer and the sealing layer are arranged on both surfaces of the pair of opposing conductive layers, respectively. [7] The electrostatic electroacoustic transducer according to any one of [1] to [6], wherein the rigidity of the buffer layer is 300 mm or less. [8] The air permeability of the buffer layer is 30 cm ３ / cm ２ An electrostatic electroacoustic transducer according to any one of [1] to [7], wherein the compression load of the buffer layer is 40 gf / cm². [9] ２ The electrostatic electroacoustic transducer according to any one of [1] to [8] below:

[10] The electrostatic electroacoustic transducer according to any one of [1] to [9] wherein the buffer layer is formed on the conductive layer by coating.

[11] A flexible electrostatic electroacoustic transducer having a pair of opposing conductive layers, a dielectric layer disposed between the pair of opposing conductive layers, a sealing layer, and a ventilation adjustment layer, wherein the sealing layer and the ventilation adjustment layer are disposed on the opposite side of one or both of the pair of opposing conductive layers from the dielectric layer, and the air permeability of the sealing layer is 0 cm３ / cm ２ 1 cm or more per second ３ / cm ２ per second or less, and the air permeability of the air permeability adjustment layer is 1 cm ３ / cm ２ more than 40 cm per second ３ / cm ２ per second or less, an electrostatic electroacoustic transducer.

[12] The electrostatic electroacoustic transducer according to

[11] , having the dielectric layer, the conductive layer, the sealing layer, and the air permeability adjustment layer in this order.

[13] The electrostatic electroacoustic transducer according to

[11] or

[12] , wherein the basis weight of the air permeability adjustment layer is larger than the basis weight of the sealing layer.

[14] The basis weight of the sealing layer is 1 g / m ２ or more and 200 g / m ２ or less, and the basis weight of the air permeability adjustment layer is 50 g / m ２ or more and 700 g / m ２The electrostatic electroacoustic transducer according to any one of

[11] to

[13] below:

[15] The electrostatic electroacoustic transducer according to any one of

[11] to

[14] , wherein the sum of the basis weights of the sealing layer and the ventilation adjusting layer is greater than the sum of the basis weights of the dielectric layer and the conductive layer.

[16] The electrostatic electroacoustic transducer according to any one of

[11] to

[15] , wherein the degree of permeability of the ventilation adjusting layer is less than the degree of permeability of the conductive layer.

[17] The electrostatic electroacoustic transducer according to any one of

[11] to

[16] , wherein the thickness of the ventilation adjusting layer is greater than the thickness of the sealing layer.

[18] The electrostatic electroacoustic transducer according to any one of

[11] to

[17] , wherein the thickness of the sealing layer is 200 μm or less, and the thickness of the ventilation adjusting layer is 10 mm or less.

[19] The electrostatic electroacoustic transducer according to any one of

[11] to

[18] , wherein the ventilation adjustment layer and the sealing layer are bonded together, and the bonding area between each layer, based on the area where the ventilation adjustment layer and the sealing layer face each other, is greater than 0% and less than or equal to 70%.

[20] The electrostatic electroacoustic transducer according to any one of

[11] to

[19] , further comprising a buffer layer disposed on the surface of one or both of the opposing pair of conductive layers opposite to the dielectric layer.

[21] The electrostatic electroacoustic transducer according to any one of

[11] to

[20] , comprising the dielectric layer, the conductive layer, the buffer layer, the sealing layer, and the ventilation adjustment layer in this order.

[22] The electrostatic electroacoustic transducer according to any one of [1] to

[21] , wherein the rigidity of the sealing layer is 300 mm or less.

[23] The electrostatic electroacoustic transducer according to any one of [1] to

[22] , wherein the dielectric breakdown voltage of the sealing layer is 3 kV or more.

[24] The electrostatic electroacoustic transducer according to any one of [1] to

[23] , wherein the water resistance of the sealing layer is 200 mm or more.

[25] The moisture permeability of the sealing layer is 400 g / m ２ - An electrostatic electroacoustic transducer described in any of [1] to

[24] , wherein h is less than or equal to h.

[0007] One aspect of the present invention that belongs to the technical field is as follows: [1A] A flexible electrostatic electroacoustic transducer having a pair of opposing conductive layers and a dielectric layer disposed between the pair of opposing conductive layers, wherein the electrostatic electroacoustic transducer further comprises: a flexible buffer layer disposed on the surface of one or both of the pair of opposing conductive layers opposite to the dielectric layer; and a flexible sealing layer disposed on the surface of the buffer layer opposite to the conductive layer. [2A] The electrostatic electroacoustic transducer according to [1A], wherein the sealing layer and the buffer layer are joined, and the buffer layer and the conductive layer are joined. [3A] The electrostatic electroacoustic transducer according to [1A] or [2A], wherein the bonding area between each layer is less than 100% with respect to the area where the sealing layer and the buffer layer face each other. [4A] An electrostatic electroacoustic transducer according to any one of [1A] to [3A], wherein the bonding area between each layer is less than 100% based on the area where the buffer layer and the conductive layer face each other. [5A] An electrostatic electroacoustic transducer according to any one of [1A] to [4A], wherein the buffer layer and the sealing layer are arranged on both surfaces of the pair of opposing conductive layers, respectively. [6A] An electrostatic electroacoustic transducer according to any one of [1A] to [5A], wherein the rigidity of the buffer layer is 300 mm or less. [7A] The air permeability of the buffer layer is 30 cm ３ / cm ２ An electrostatic electroacoustic transducer according to any one of [1A] to [6A], wherein the compression load of the cushioning material layer is 40 gf / cm². [8A] ２ The electrostatic electroacoustic transducer according to any of [1A] to [7A] below: [9A] The electrostatic electroacoustic transducer according to any of [1A] to [8A] wherein the rigidity of the sealing layer is 300 mm or less. [10A] The electrostatic electroacoustic transducer according to any of [1A] to [9A] wherein the dielectric breakdown voltage of the sealing layer is 3 kV or more. [11A] The electrostatic electroacoustic transducer according to any of [1A] to [10A] wherein the water resistance of the sealing layer is 200 mm or more. [12A] The moisture permeability of the sealing layer is 400 g / m ２- An electrostatic electroacoustic transducer according to any one of [1A] to [11A], wherein the value is less than or equal to h. [13A] An electrostatic electroacoustic transducer according to any one of [1A] to [12A], wherein the buffer layer is formed on the conductive layer by coating.

[0008] Furthermore, a further embodiment belonging to the technical field of the present invention is as follows: [1B] A flexible electrostatic electroacoustic transducer having a pair of opposing conductive layers, a dielectric layer disposed between the pair of opposing conductive layers, a sealing layer, and a ventilation adjustment layer, wherein the sealing layer and the ventilation adjustment layer are disposed on the opposite side of one or both of the pair of opposing conductive layers from the dielectric layer, and the air permeability of the sealing layer is 0 cm ３ / cm ２ / sec or more 1cm ３ / cm ２ The value is less than / second, and the air permeability of the ventilation adjustment layer is 1 cm ３ / cm ２ / second over 40cm ３ / cm ２ [2B] An electrostatic electroacoustic transducer having a voltage of less than / second. [2B] The electrostatic electroacoustic transducer according to [1B], wherein the dielectric layer, the conductive layer, the sealing layer, and the ventilation adjustment layer are arranged in this order. [3B] The electrostatic electroacoustic transducer according to [1B] or [2B], wherein the basis weight of the ventilation adjustment layer is greater than the basis weight of the sealing layer. [4B] The basis weight of the sealing layer is 1 g / m ２ More than 200g / m ２ The electrostatic electroacoustic transducer described in any of the following [3B]: [5B] The basis weight of the ventilation adjustment layer is 50 g / m ２ 700g / m or more ２The electrostatic electroacoustic transducer according to [3B] or [4B], which is as follows: [6B] The electrostatic electroacoustic transducer according to any one of [3B] to [5B], wherein the sum of the basis weights of the sealing layer and the ventilation adjustment layer is greater than the sum of the basis weights of the dielectric layer and the conductive layer. [7B] The electrostatic electroacoustic transducer according to any one of [1B] to [6B], wherein the degree of permeability of the ventilation adjustment layer is less than the degree of permeability of the conductive layer. [8B] The electrostatic electroacoustic transducer according to any one of [1B] to [7B], wherein the thickness of the ventilation adjustment layer is greater than the thickness of the sealing layer. [9B] The electrostatic electroacoustic transducer according to [8B], wherein the thickness of the sealing layer is 200 μm or less. [10B] The electrostatic electroacoustic transducer according to [8B] or [9B], wherein the thickness of the ventilation adjustment layer is 10 mm or less. [11B] The electrostatic electroacoustic transducer according to any one of [1B] to [10B], wherein the ventilation adjustment layer and the sealing layer are bonded together, and the bonding area between each layer, based on the area where the ventilation adjustment layer and the sealing layer face each other, is greater than 0% and less than or equal to 70%. [12B] The electrostatic electroacoustic transducer according to any one of [1B] to [11B], wherein the dielectric breakdown voltage of the sealing layer is 3kV or more. [13B] The electrostatic electroacoustic transducer according to any one of [1B] to [12B], wherein the rigidity of the ventilation adjustment layer is 300 mm or less. [14B] The electrostatic electroacoustic transducer according to any one of [1B] to [13B], further comprising a buffer layer disposed on the surface of one or both of the opposing pair of conductive layers opposite to the dielectric layer. [15B] The electrostatic electroacoustic transducer according to [14B], wherein the dielectric layer, the conductive layer, the buffer layer, the sealing layer, and the ventilation adjustment layer are arranged in this order.

[0009] According to this disclosure, it is possible to provide a flexible electrostatic electroacoustic transducer that, while having a sealing layer for purposes such as water and insulation, can generate sound waves with high sound pressure, low noise generation, and excellent sound quality.

[0010] Figure 1 is a schematic diagram showing a preferred laminated structure of the electrostatic electroacoustic transducer of the present disclosure. Figure 2 is a schematic diagram showing the joint shape between the buffer layer and the conductive layer of the electrostatic electroacoustic transducer in Example 1A. Figure 3 is a schematic diagram showing the joint shape between the buffer layer and the sealing layer of the electrostatic electroacoustic transducer in Example 1A. Figure 4 is a schematic diagram showing a preferred laminated structure of the electrostatic electroacoustic transducer of the present disclosure.

[0011] The embodiments of this disclosure will be described in detail below, but this disclosure is not limited to the embodiments described below. The upper and lower limits in each numerical range of the embodiments described below can be arbitrarily combined to form any numerical range.

[0012] [First Embodiment] The electrostatic electroacoustic transducer of this disclosure is a flexible electrostatic electroacoustic transducer having a pair of opposing conductive layers and a dielectric layer disposed between the pair of opposing conductive layers. By applying a voltage to the pair of conductive layers, the dielectric layer becomes charged, and an electrostatic force (Coulomb force) can be generated between the dielectric layer and the conductive layer. Then, by applying an electrical signal to the pair of conductive layers, the attractive or repulsive force due to the electrostatic force changes, and the dielectric layer and the conductive layer vibrate together to generate sound waves. In this disclosure, "sound waves" are not limited to sounds that can be heard by humans, but include sound waves and ultrasound. The applications are not limited, but when the electrostatic electroacoustic transducer emits sound waves that can be heard by humans, it can be used for music / voice playback, communication, notification, and alarms, etc. When it generates ultrasound, it can be used for detection (sonar), measurement, diagnosis, treatment, and pest control (insect repellent), etc.

[0013] The electrostatic electroacoustic transducer of this disclosure is flexible. The degree of flexibility is not limited, but the rigidity of the electrostatic electroacoustic transducer as a whole, as measured in accordance with JIS L1096:2010, Method A (45° cantilever method), is preferably 300 mm or less.

[0014] By using relatively thin and flexible materials as the conductive layer, dielectric layer, cushioning layer, and sealing layer that constitute the electrostatic electroacoustic transducer, the electrostatic electroacoustic transducer as a whole can be made flexible. Because the electrostatic electroacoustic transducer is flexible, it can be made in a small space and conform to any shape, thus offering a very high degree of design freedom. Furthermore, the sound waves generated from a flexible electrostatic electroacoustic transducer are close to plane waves and have high directivity. For this reason, flexible electrostatic electroacoustic transducers can be suitably used, for example, on surfaces in spaces such as the interior of a vehicle and a room, as well as on clothing and accessories. More specifically, flexible electrostatic electroacoustic transducers can be attached to the flat and curved surfaces of various items, such as car seats, front pillars, dashboards, sun visors, ceilings, door panels, and floors; interior walls, floors, ceiling columns, and curtains; and clothing, such as the inside of a hood. The electrostatic electroacoustic transducer of this disclosure will be described below with reference to the drawings.

[0015] The electrostatic electroacoustic transducer 10 of the present disclosure is an electrostatic electroacoustic transducer that further comprises, as shown in Figure 1, a flexible buffer layer 3 disposed on the surface of one or both of a pair of opposing conductive layers 2 opposite to the dielectric layer 1, and a flexible sealing layer 4 disposed on the surface of the buffer layer 3 opposite to the conductive layer 2. In one embodiment, the electrostatic electroacoustic transducer 10 of the present disclosure is an electrostatic electroacoustic transducer in which the buffer layer 3 and the sealing layer 4 are disposed on both surfaces of a pair of opposing conductive layers 2, respectively, as shown in Figure 1.

[0016] <Dielectric Layer> The dielectric layer can be charged and vibrated by applying voltage and electrical signals, thereby generating sound waves. The dielectric layer is preferably a sheet or film of a non-conductive material.

[0017] The lower limit of the dielectric layer thickness is greater than 0 μm, for example, 1 μm or more, 5 μm or more, 10 μm or more, or 20 μm or more. The upper limit of the dielectric layer thickness, which can be arbitrarily combined with these lower limits, is 500 μm or less, preferably 400 μm or less, more preferably 300 μm or less, even more preferably 200 μm or less, or 100 μm or less.

[0018] Preferably, the conductive layer and the dielectric layer are made of different materials on the triboelectric series. In an electrostatic electroacoustic transducer, the dielectric layer becomes charged when a voltage is applied, and can vibrate due to the electrostatic force (Coulomb force) generated between the dielectric layer and the conductive layer. At this time, because the conductive layer and the dielectric layer are made of different materials on the triboelectric series, the amount of charge in the dielectric layer becomes larger due to triboelectric charging caused by the vibration of the dielectric layer, and an effect similar to that when a high potential is applied can be obtained, and the sound pressure can be increased.

[0019] The dielectric layer material is preferably at least one selected from the group consisting of silicone, fluororesin, polyolefin, and rubber, with fluororesin being preferred. Examples of fluororesins include tetrafluoroethylene resin (PTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and ethylene tetrafluoroethylene (ETFE). A commercially available fluororesin is Poaflon® membrane, manufactured by Sumitomo Electric Fine Polymer Co., Ltd., product number HP-010-30. Examples of polyolefins include polyolefins with 2 to 10 or 2 to 5 carbon atoms, substituted or unsubstituted, linear or branched chains, such as polyethylene, polypropylene, and polybutylene. Examples of rubbers include natural rubber or synthetic rubber, such as nitrile rubber, butadiene rubber, styrene rubber, chloroprene rubber, acrylic rubber, and urethane rubber. The dielectric layer material may be one of these materials used alone, or two or more may be used in combination.

[0020] <Conductive Layer> The conductive layer is not particularly limited as long as a voltage can be applied to the dielectric layer. For example, the conductive layer can be a fibrous structure containing conductive fibers, or a fibrous structure having a conductive material-containing layer arranged on one or both sides. Examples of fibrous structures include woven fabrics, knitted fabrics, and nonwoven fabrics, with nonwoven fabrics being preferred. Because the conductive layer is a nonwoven fabric, thread fraying (loosening) from the edges is less likely to occur, and short-circuit failures are suppressed. Examples of commercially available nonwoven fabrics that can be used as fibrous structures include Presize®, manufactured by M.A. Life Materials Co., Ltd., model number AC1050, etc.

[0021] When the conductive layer is a fibrous structure containing conductive fibers, examples of conductive fibers include metal fibers, metal-coated fibers, conductive polymer-containing fibers, and carbon fibers. Examples of metal components in metal fibers and metal-coated fibers include metals such as gold, platinum, silver, copper, nickel, chromium, iron, zinc, aluminum, tungsten, stainless steel, titanium, magnesium, tin, vanadium, cobalt, molybdenum, and tantalum, as well as their alloys. As conductive fibers, fibers in which a metal film mainly composed of silver is formed on a chemical fiber are preferred from the viewpoint of conductivity and flexibility. Here, "main component" means the component that accounts for the largest mass % of the components constituting the metal film. Examples of conductive polymers include polyacetylene and polythiophene. Examples of carbon fibers include polyacrylonitrile (PAN) carbon fibers, pitch carbon fibers, and carbon fibers spun from carbon nanotubes. Conductive fibers may be used individually or in combination of two or more. In addition, other fibers may be combined with the above conductive fibers.

[0022] When the conductive layer is a fibrous structure having a conductive material-containing layer, the fibers constituting the fibrous structure may be the conductive fibers listed above, other fibers, or a combination thereof. Examples of fibers include synthetic fibers and natural fibers, such as polyester, polyamide, polyvinyl alcohol, polyvinylidene chloride, polyvinyl chloride, polyacrylonitrile, polyethylene, polypropylene, polyurethane, aramid, cellulose, cotton, linen, wool, and silk. These fibers may be used individually or in combination of two or more.

[0023] Examples of conductive materials in the conductive material-containing layer include metals, conductive polymers, and carbon materials. Examples of metallic components include those similar to those in metal fibers and metal-coated fibers, and a conductive material-containing layer having at least one selected from the group consisting of copper, tin, nickel, aluminum, gold, silver, and zinc as the main component is preferred from the viewpoint of conductivity. Here, "main component" means the component that accounts for the largest mass % of the components constituting the conductive material-containing layer. Examples of conductive polymers include polyacetylene and polythiophene. Examples of carbon materials include carbon black, carbon nanotubes, and graphene. Conductive materials may be used individually or in combination of two or more.

[0024] The conductive material-containing layer can be formed on one or both sides of the fibrous structure. Methods for forming the conductive material-containing layer include coating, plating, sputtering, and vapor deposition.

[0025] Preferably, one or both of the pair of conductive layers and the dielectric layer are joined to each other at least in part. This allows the conductive and dielectric layers to adhere closely together, making it easier for electrostatic force (Coulomb force) to be generated, thus improving sound pressure. Furthermore, when the electrostatic electroacoustic transducer deforms or when frictional force is applied to the surface, the displacement of the conductive and dielectric layers in the planar direction is suppressed.

[0026] Examples of joining methods include sewing using non-conductive fibers and bonding using adhesives. The joining may consist of a single continuous joining region or a discrete joining that includes two or more discontinuous joining regions. An example of a continuous joining is to continuously join the outer periphery of a laminated conductive layer and dielectric layer, leaving the inner portion unjoined. A discrete joining may be a pattern of any shape, such as a dot pattern, a stripe pattern, a grid pattern, or a combination thereof.

[0027] The thickness of the conductive layer is not particularly limited, but from the viewpoint of flexibility and space saving, it may be, for example, 1 μm or more and 1000 μm or less. The lower limit of the thickness of the conductive layer is, for example, 1 μm or more, 5 μm or more, 10 μm or more, 50 μm or more, or 100 μm or more. The upper limit of the thickness of the conductive layer, which can be arbitrarily combined with these lower limits, is, for example, 1000 μm or less, 500 μm or less, 300 μm or less, 200 μm or less, or 100 μm or less.

[0028] <Buffer Layer> In addition to the conductive layer and dielectric layer described above, the electrostatic electroacoustic transducer has a buffer layer disposed on the surface opposite to the dielectric layer of one or both of the opposing pair of conductive layers. The buffer layer is flexible and isolates the dielectric layer from external people or other articles (or the sealing layer described later), and ensures the amplitude of the conductive layer and dielectric layer, thereby improving the sound pressure of the electrostatic electroacoustic transducer. The presence of a buffer layer in the electrostatic electroacoustic transducer prevents people or other articles from directly touching the conductive layer. It also prevents the sealing layer from directly touching the conductive layer and interfering with the vibration of the conductive layer and dielectric layer.

[0029] The cushioning layer is preferably made of a highly permeable material from the viewpoint of easily transmitting sound waves, and is preferably a fibrous structure. Examples of fibrous structures include woven fabrics, knitted fabrics, and nonwoven fabrics, and nonwoven fabrics are preferred from the viewpoint of permeability and adhesion between the cushioning layer and the conductive layer, and between the cushioning layer and the sealing layer.

[0030] From a safety standpoint, the fibrous structure of the cushioning layer is preferably composed of non-conductive fibers. Examples of non-conductive fibers include synthetic fibers and natural fibers, such as nylon, polyester (Pe), polyamide, polyvinyl alcohol, polyvinylidene chloride, polyvinyl chloride, polyacrylonitrile, polyethylene, polypropylene, polyurethane (Pu), aramid, cellulose, cotton, linen, wool, and silk. These fibers may be used individually or in combination of two or more. Examples of commercially available fibrous structures that can be used as cushioning layers include Free Cut Mesh, manufactured by Asahi Kasei Advance Corporation, product number AS255035G, "Fusion AKE64334" manufactured by Asahi Kasei Corporation, and 3D FINEX®, manufactured by Asahi Kasei Advance Corporation.

[0031] From the viewpoint of flexibility, the rigidity of the buffer layer in the electrostatic electroacoustic transducer of this disclosure is preferably 300 mm or less, more preferably 200 mm or less, even more preferably 50 mm or less, and particularly preferably 10 mm or less. The rigidity of the buffer layer is measured by the method described in the examples.

[0032] From the viewpoint of improving sound pressure and suppressing noise, the lower limit of the air permeability of the buffer layer in the electrostatic electroacoustic transducer of this disclosure is preferably 30 cm. ３ / cm ２ More than 50 cm / second, comfortable ３ / cm ２ / second or more, more preferably 100 cm ３ / cm ２ / second or more, particularly preferably 200 cm ３ / cm ２ It is more than / second. The upper limit of the air permeability of the buffer layer is preferably 700 cm. ３ / cm ２ Less than 650 cm / second, more preferably 650 cm / second ３ / cm ２ It is less than / second. The air permeability of the cushioning material layer is measured by the method described in the examples.

[0033] From the viewpoint of improving sound pressure and suppressing noise, the upper limit of the compressive load of the buffer layer in the electrostatic electroacoustic transducer of this disclosure is preferably 40 gf / cm².２ More preferably, 30 gf / cm² ２ More preferably, 10 gf / cm² ２ The following is particularly preferable: 5 gf / cm² ２ Below, the most preferred is 0.5 gf / cm². ２ The following applies: The lower limit of the compressive load of the buffer layer in the electrostatic electroacoustic transducer of this disclosure is preferably 0.01 gf / cm². ２ More preferably 0.1 gf / cm² ２ That concludes the explanation. The compression load of the cushioning material layer is measured by the method described in the examples.

[0034] <Bonding of Conductive Layer and Buffer Layer> In the electrostatic electroacoustic transducer of this disclosure, it is preferable that a buffer layer is bonded to one or both of a pair of opposing conductive layers. When the conductive layer and the buffer layer are bonded, from the viewpoint of suppressing noise due to friction, the peel strength is preferably 0.15 N / cm or more, more preferably 0.3 N / cm or more, and even more preferably 0.5 N / cm or more. The peel strength when the conductive layer and the buffer layer are bonded in this disclosure is measured by the method described in the examples. The bonding method is not particularly limited, but includes "discrete" bonding or "continuous" bonding, and "discrete" bonding is preferred. Here, "discrete" bonding means bonding that includes two or more discontinuous bonding regions (hereinafter also referred to as "discrete bonding"), rather than bonding consisting of a single continuous bonding region (hereinafter also referred to as "continuous bonding"). Although not limited to theory, it is preferable to bond the conductive layer and the buffer layer to each other in order to suppress the displacement of the conductive layer and the buffer layer in the planar direction when the electrostatic electroacoustic transducer is deformed or when a frictional force is applied to its surface.

[0035] Examples of discrete joining methods include sewing using non-conductive fibers and bonding using adhesives.

[0036] Examples of threads (fibers) used for sewing include synthetic fibers and natural fibers such as polyester, polyamide, polyvinyl alcohol, polyvinylidene chloride, polyvinyl chloride, polyacrylonitrile, polyethylene, polypropylene, polyurethane, aramid, cellulose, cotton, linen, wool, and silk. These fibers may be used individually or in combination of two or more.

[0037] Examples of adhesives used for bonding include thermoplastic resins and thermosetting resins, such as acrylic, vinyl acetate, polyvinyl acetal, vinyl chloride, polyester, polyamide, cellulose, olefin, styrene, urethane, epoxy, and silicone adhesives. These adhesives may be used individually or in combination of two or more.

[0038] The shape of the discrete junction may be any pattern, such as dots, stripes, grids, or combinations thereof. The discrete junction may consist of a single pattern over the entire region where the conductive layer and the buffer layer face each other, or it may consist of a combination of multiple patterns.

[0039] From the viewpoint of improving sound pressure, it is preferable that the bonding area between each layer is less than 100%, more preferably 95% or less, and even more preferably 90% or less, based on the area where the conductive layer and the buffering layer face each other. Furthermore, it is preferable that the bonding area between each layer is greater than 0%, and more preferably 20% or more, based on the area where the conductive layer and the buffering layer face each other.

[0040] In the case of sewing, the shape of the joint corresponds to a linear shape with a constant width corresponding to the thread width when the surface of the electrostatic electroacoustic transducer is observed from the front. Therefore, discrete joints by sewing can be composed of a combination of two or more non-intersecting linear joints. The joint area is calculated as the percentage of the area where the linear joint exists within the area where the conductive layer and the buffer layer face each other.

[0041] In the case of bonding, the shape of the bond corresponds to the shape of the area where the adhesive exists (bonding area) when the surface of the electrostatic electroacoustic transducer is observed from the front (viewpoint indicated by the arrow 10 in the figure). Therefore, discrete bonding by adhesive can be composed of a combination of two or more discontinuous bonding areas. The bonding area is calculated as the percentage (%) of the total area of ​​the bonding area that occupies the area where the conductive layer and the buffer layer face each other.

[0042] One method of bonding is to apply an adhesive to the surface of the conductive layer using any method, and then bond the conductive layer and the buffer layer together. Methods for applying the adhesive include intaglio printing, spraying, casting, bar coating, and brushing. From the viewpoint of productivity, intaglio printing is preferred as the application method.

[0043] The buffer layer may be formed on the conductive layer by coating, and the coating method is not particularly limited. In one embodiment, the buffer layer may be formed by coating a molten resin (for example, polyurethane resin) onto the conductive layer by gravure printing or other intaglio printing.

[0044] <Sealing Layer> In addition to the conductive layer, dielectric layer, and buffer layer described above, the electrostatic electroacoustic transducer further includes a sealing layer disposed on the buffer layer. The sealing layer is flexible and electrically insulates the electrostatic electroacoustic transducer from the surrounding environment. The sealing layer can also prevent water, dust, etc. from entering the interior. The presence of a sealing layer in the electrostatic electroacoustic transducer improves safety and durability. From the viewpoint of waterproofing and dustproofing, it is preferable that the sealing layer does not have through holes, but depending on the embodiment, the sealing layer may have through holes.

[0045] The sealing layer is preferably a sheet or film of a non-conductive material from the viewpoint of electrical insulation, waterproofing, and dustproofing. Examples of non-conductive materials for the sealing layer include polyurethane, silicone, and rubber, with polyurethane being preferred from the viewpoint of flexibility, safety, durability, and adhesion. The sealing layer material may be one of these alone or two or more in combination. Examples of commercially available non-conductive materials that can be used as a sealing layer include ester-based polyurethane resin films (Mobilon®, manufactured by Nisshinbo Textile Co., Ltd., product numbers MF100T and MF200T, and Esmer® URS, manufactured by Nippon Matai Co., Ltd.).

[0046] From the viewpoint of flexibility, the rigidity / softness of the sealing layer of the electrostatic electroacoustic transducer of this disclosure is preferably 300 mm or less, more preferably 200 mm or less, even more preferably 50 mm or less, and particularly preferably 10 mm or less. The rigidity / softness of the sealing layer of this disclosure is measured by the method described in the examples.

[0047] The water resistance of the sealing layer of the electrostatic electroacoustic transducer of this disclosure is preferably 200 mm or more, more preferably 400 mm or more, even more preferably 600 mm or more, and particularly preferably 1000 mm or more. The water resistance of the sealing layer of this disclosure is measured by the method described in the examples.

[0048] The moisture permeability of the sealing layer of the electrostatic electroacoustic transducer of this disclosure is preferably 400 g / m². ２ - h or less, more preferably 300 g / m ２ - h or less, more preferably 200 g / m ２ - h or less, particularly preferably 100 g / m ２ - It is less than or equal to h. The moisture permeability of the sealing layer of this disclosure is measured by the method described in the examples.

[0049] The dielectric breakdown voltage of the sealing layer is preferably 3 kV or higher, more preferably 5 kV or higher. A higher dielectric breakdown voltage of the sealing layer is preferable because it means a wider tolerance range for the applied voltage. The upper limit of the dielectric breakdown voltage of the sealing layer, which can be arbitrarily combined with these lower limits, is not limited but may be 20 kV or less. The dielectric breakdown voltage of the sealing layer in this disclosure is measured by the method described in the examples.

[0050] The air permeability of the sealing layer in the electrostatic electroacoustic transducer of this disclosure is preferably 30 cm². ３ / cm ２ Less than or equal to 0 cm / second, more preferably 0 cm ３ / cm ２ It is less than / second. The air permeability of the sealing layer of this disclosure is measured by the method described in the examples.

[0051] <Bonding of the sealing layer and the buffering layer> In the electrostatic electroacoustic transducer of this disclosure, it is preferable that the buffering layer and the sealing layer are bonded together. When the sealing layer and the buffering layer are bonded together, the peel strength is preferably 0.15 N / cm or more, more preferably 0.3 N / cm or more, and even more preferably 0.5 N / cm or more. The bonding method is not particularly limited, but includes discrete bonding or continuous bonding, with discrete bonding being preferred. In the electrostatic electroacoustic transducer of this disclosure, it is preferable that the sealing layer and the buffering layer are bonded together, and that the buffering layer and the conductive layer are bonded together.

[0052] Examples of discrete joining methods include sewing and adhesives using non-conductive fibers, and bonding by high temperature and pressure.

[0053] Examples of threads (fibers) used for sewing include synthetic fibers and natural fibers such as polyester, polyamide, polyvinyl alcohol, polyvinylidene chloride, polyvinyl chloride, polyacrylonitrile, polyethylene, polypropylene, polyurethane, aramid, cellulose, cotton, linen, wool, and silk. These fibers may be used individually or in combination of two or more. In the case of sewing, it is preferable to perform post-processing (surface treatment, etc.) to fill the sewing holes on the surface of the sealing layer.

[0054] Examples of adhesives used for bonding include thermoplastic resins and thermosetting resins, such as acrylic, vinyl acetate, polyvinyl acetal, vinyl chloride, polyester, polyamide, cellulose, olefin, styrene, urethane, epoxy, and silicone adhesives. These adhesives may be used individually or in combination of two or more.

[0055] Bonding may be performed by hot pressing using high temperature and pressure. Hot pressing can be performed at temperatures ranging from 75°C to 150°C and pressures ranging from 0.02 MPa to 3 MPa. The hot pressing time is 3 seconds to 2 minutes.

[0056] The shape of the discrete joint may be any pattern, such as dots, stripes, grids, or combinations thereof. The discrete joint may consist of a single pattern over the entire region where the buffer layer and the sealing layer face each other, or it may consist of a combination of multiple patterns.

[0057] Based on the area where the sealing layer and the cushioning layer face each other, the bonding area between each layer is preferably less than 100%, more preferably 95% or less, and even more preferably 90% or less. Furthermore, based on the area where the sealing layer and the cushioning layer face each other, the bonding area between each layer is preferably greater than 0%, and more preferably 20% or more.

[0058] In the case of sewing, the shape of the joint corresponds to a linear shape with a constant width corresponding to the thread width when the surface of the electrostatic electroacoustic transducer is observed from the front (viewpoint of arrow 10 in the figure). Therefore, discrete joints by sewing can be composed of a combination of two or more non-intersecting linear joints. The joint area is calculated as the percentage of the area where the linear joint exists within the area where the sealing layer and the cushioning layer face each other.

[0059] In the case of bonding, the shape of the joint corresponds to the shape of the area where the adhesive exists (bonding area) when the surface of the electrostatic electroacoustic transducer is observed from the front (viewpoint indicated by the arrow 10 in the figure). Therefore, discrete bonding by adhesive can be composed of a combination of two or more discontinuous bonding areas. The bonding area is calculated as the percentage (%) of the total area of ​​the bonding area that occupies the area where the sealing layer and the buffer layer face each other.

[0060] One method of bonding is to apply an adhesive to the surface of the sealing layer using any method, and then bond the sealing layer and the cushioning layer together. Methods for applying the adhesive include intaglio printing, spraying, casting, bar coating, and brushing. From the viewpoint of productivity, intaglio printing is preferred as the application method. In a preferred embodiment, the sealing layer is in the form of a sheet or film, and the cushioning layer is a fibrous structure. Therefore, if the adhesive is applied to the cushioning layer first, the adhesive may penetrate the fibrous structure, making it difficult to bond with the sealing layer. For this reason, it is preferable to apply the adhesive to the sealing layer first, and then bond it with the cushioning layer.

[0061] [Second Embodiment] A second embodiment of the present invention will be described below. This embodiment may be implemented in combination with the first embodiment described above, and some of the constituent elements of this embodiment may be implemented in combination with the first embodiment described above.

[0062] [Background Art Related to the Second Embodiment] Conventionally, a flexible electrostatic electroacoustic transducer is known as one type of acoustic device. A flexible electrostatic electroacoustic transducer generally has a dielectric layer and a pair of conductive layers arranged opposite each other on both sides of the dielectric layer. By applying an electrical signal to the pair of conductive layers, the dielectric layer and the conductive layers vibrate together to generate sound waves. By using thin, flexible materials as the dielectric layer and the conductive layer, the electrostatic electroacoustic transducer as a whole can be made flexible.

[0063] For example, Patent Document 1 describes an electrostatic speaker characterized by comprising: a vibrating membrane made of a thin film member; a conductive, acoustically transparent planar electrode positioned opposite the vibrating membrane; and a buffer member positioned between the vibrating membrane and the planar electrode, formed by including a material that is at least opposite the vibrating membrane in the triboelectric series.

[0064] [Problems related to the second embodiment] The technology described in Patent Document 1 aims to obtain an electrostatic speaker that requires a lower applied voltage to be applied to the diaphragm in order to generate sound. However, in a flexible electroacoustic transducer, the frequency balance of the sound pressure obtained when a certain voltage is applied is not always good. For example, when trying to obtain the desired sound pressure in the low-frequency to medium-frequency range, there is a problem that the sound pressure in the high-frequency range becomes excessive.

[0065] The problem related to the second embodiment is to solve the above problem and provide a flexible electrostatic electroacoustic transducer that can obtain a desired sound pressure and has an excellent balance of sound quality between high and low frequencies.

[0066] [Effects related to the second embodiment] The flexible electrostatic electroacoustic transducer related to the second embodiment can obtain the desired sound pressure and has an excellent balance of sound quality between high and low frequencies.

[0067] [Specific Configuration of the Second Embodiment] This embodiment will now be described in detail. This embodiment is a flexible electrostatic electroacoustic transducer having a pair of opposing conductive layers and a dielectric layer disposed between the pair of opposing conductive layers. By applying a voltage to the pair of conductive layers, the dielectric layer becomes charged, and an electrostatic force (Coulomb force) can be generated between the dielectric layer and the conductive layer. Then, by applying an electrical signal to the pair of conductive layers, the attractive or repulsive force due to the electrostatic force changes, and the dielectric layer and the conductive layer vibrate together to generate sound waves. In this disclosure, "sound waves" are not limited to sounds that can be heard by humans, but include sound waves and ultrasound. The applications are not limited, but when the electrostatic electroacoustic transducer emits sound waves that can be heard by humans, it can be used for music / voice playback, communication, notification, and alarms, etc. When it generates ultrasound, it can be used for detection (sonar), measurement, diagnosis, treatment, and pest control (insect repellent), etc.

[0068] The electrostatic electroacoustic transducer of this disclosure is flexible. The degree of flexibility is not limited, but the rigidity of the electrostatic electroacoustic transducer as a whole, as measured in accordance with JIS L1096:2010, Method A (45° cantilever method), is preferably 300 mm or less.

[0069] By using relatively thin and flexible materials for the conductive layer, dielectric layer, ventilation adjustment layer, and sealing layer that constitute the electrostatic electroacoustic transducer, the electrostatic electroacoustic transducer as a whole can be made flexible. Because the electrostatic electroacoustic transducer is flexible, it can be made in a small space and conform to any shape, thus offering a very high degree of design freedom. Furthermore, the sound waves generated from a flexible electrostatic electroacoustic transducer are close to plane waves and have high directivity. Therefore, flexible electrostatic electroacoustic transducers can be suitably used, for example, on surfaces in spaces such as the interior of a vehicle and a room, as well as on clothing and accessories. More specifically, flexible electrostatic electroacoustic transducers can be attached to the flat and curved surfaces of various items, such as car seats, front pillars, dashboards, sun visors, ceilings, door panels, and floors; interior walls, floors, ceiling columns, and curtains; and clothing, such as the inside of a hood. The electrostatic electroacoustic transducer of this disclosure will be described below with reference to the drawings.

[0070] The electrostatic electroacoustic transducer 10 of the present disclosure is an electrostatic electroacoustic transducer having a pair of opposing conductive layers 2, a dielectric layer 1 disposed between the pair of opposing conductive layers 2, a sealing layer 4, and a ventilation adjustment layer 7, as shown in Figure 4. In one embodiment, the electrostatic electroacoustic transducer 10 of the present disclosure is an electrostatic electroacoustic transducer having a dielectric layer 1, a conductive layer 2, a sealing layer 4, and a ventilation adjustment layer 7 in this order, as shown in Figure 4. In one embodiment, the electrostatic electroacoustic transducer 10 of the present disclosure is an electrostatic electroacoustic transducer having a buffer layer 3 on the surface opposite to the dielectric layer 1 of one or both of the pair of opposing conductive layers 2, as shown in Figure 4. In one embodiment, the electrostatic electroacoustic transducer 10 of the present disclosure is an electrostatic electroacoustic transducer having a dielectric layer 1, a conductive layer 2, a buffer layer 3, a sealing layer 4, and a ventilation adjustment layer 7 in this order, as shown in Figure 4.

[0071] Preferred embodiments of the dielectric layer and conductive layer according to the second embodiment are the same as preferred embodiments of the electrostatic electroacoustic transducer according to the first embodiment described above.

[0072] <Sealing Layer> The electrostatic electroacoustic transducer of this disclosure has a sealing layer in addition to the conductive layer and dielectric layer described above. The sealing layer of this disclosure is disposed on one or both of the opposing pair of conductive layers, on the side opposite to the dielectric layer. The sealing layer is flexible and electrically insulates the electrostatic electroacoustic transducer from the surrounding environment. The sealing layer can also prevent water, dust, etc. from entering the interior. By having a sealing layer in the electrostatic electroacoustic transducer, safety and durability can be improved. From the viewpoint of waterproofing and dustproofing, it is preferable that the sealing layer does not have through holes, but depending on the embodiment, the sealing layer may have through holes.

[0073] The sealing layer is preferably a sheet or film of a non-conductive material from the viewpoint of electrical insulation, waterproofing, and dustproofing. Examples of non-conductive materials for the sealing layer include polyurethane, silicone, and rubber, with polyurethane being preferred from the viewpoint of flexibility, safety, durability, and adhesion. The sealing layer material may be one of these alone or two or more in combination. Examples of commercially available non-conductive materials that can be used as a sealing layer include ester-based polyurethane resin films (Mobilon®, manufactured by Nisshinbo Textile Co., Ltd., product numbers MF100T and MF200T, and Esmer® URS, manufactured by Nippon Matai Co., Ltd.).

[0074] The basis weight of the sealing layer (or the basis weight of each conductive layer if it is provided on both sides) of the electrostatic electroacoustic transducer of this disclosure is preferably 1 g / m². ２ More than 200g / m ２ The following is more preferable: 10 g / m ２ 150g / m or more ２ The following applies. From the viewpoint of obtaining good functionality as a sealing layer, the basis weight is preferably above the lower limit, and from the viewpoint of sound pressure (i.e., from the viewpoint of easily obtaining high sound pressure), it is preferably below the upper limit. The basis weight of the sealing layer of this disclosure is measured by the method described in the examples.

[0075] The dielectric breakdown voltage of the sealing layer in the electrostatic electroacoustic transducer of this disclosure is preferably 3 kV or higher, more preferably 5 kV or higher. A higher dielectric breakdown voltage of the sealing layer is preferable because it means a wider tolerance range for the applied voltage. The upper limit of the dielectric breakdown voltage of the sealing layer, which can be arbitrarily combined with these lower limits, is not limited but may be 20 kV or less. The dielectric breakdown voltage of the sealing layer in this disclosure is measured by the method described in the examples.

[0076] The air permeability of the sealing layer of the electrostatic electroacoustic transducer of this disclosure is 0 cm ３ / cm ２ / sec or more 1cm ３ / cm ２ It is less than / second. From the viewpoint of obtaining good functionality as a sealing layer, a lower air permeability is preferable. From this viewpoint, the upper limit of the air permeability of the sealing layer in this disclosure is preferably 0.9 cm. ３ / cm ２ Less than or equal to one second, more preferably 0.7 cm ３ / cm ２ It is less than / second. The air permeability of the sealing layer is 0 cm ３ / cm ２ It is acceptable if it is more than / second, but from the viewpoint of breathability, in one embodiment, 0.3 cm ３ / cm ２ / second or more, or 0.5 cm ３ / cm ２ The rate may be greater than or equal to one second. The air permeability of the sealing layer of this disclosure is measured by the method described in the examples.

[0077] The thickness of the sealing layer is not particularly limited, but from the viewpoint of obtaining good functionality as a sealing layer, it may be, for example, 10 μm or more, and from the viewpoint of flexibility and sound pressure, it may be, for example, 200 μm or less. The lower limit of the sealing layer thickness is, for example, 20 μm or more, 30 μm or more, 40 μm or more, or 50 μm or more. The upper limit of the sealing layer thickness, which can be arbitrarily combined with these lower limits, is, for example, 200 μm or less, 150 μm or less, or 100 μm or less. The thickness of the sealing layer in this disclosure is measured by the method described in the examples.

[0078] <Ventilation Adjustment Layer> The electrostatic electroacoustic transducer of this disclosure has a ventilation adjustment layer in addition to the conductive layer, dielectric layer and sealing layer described above. The ventilation adjustment layer of this disclosure is preferably placed on the sealing layer of this disclosure from the viewpoint of adjusting the frequency balance without attenuating sound pressure. In one embodiment, the ventilation adjustment layer of this disclosure may be placed below the sealing layer. Conventionally, in flexible electrostatic electroacoustic transducers, when trying to obtain a desired sound pressure from the low frequency region (e.g., the region including a frequency of 500 Hz) to the medium frequency region (e.g., the region including a frequency of 1000 Hz), there is a problem that the sound pressure in the high frequency region (e.g., the region including a frequency of 5000 Hz) becomes excessive. The ventilation adjustment layer of this disclosure has the ability to selectively absorb high frequencies by having a specific degree of ventilation in the subsequent stage. By including the ventilation adjustment layer, the electrostatic electroacoustic transducer of this disclosure can obtain a desired sound pressure while also having an excellent balance of sound quality between high and low frequencies, even though it is an electrostatic type.

[0079] The breathability adjustment layer of this disclosure is preferably a fibrous structure whose breathability is controlled within a predetermined range from the viewpoint of high-frequency cut. Examples of fibrous structures include woven fabrics, knitted fabrics, and nonwoven fabrics, and is preferably a nonwoven fabric (for example, artificial leather). Examples of commercially available nonwoven fabrics that can be used as fibrous structures include Presize®, model number C5210, manufactured by Asahi Kasei Corporation. Examples of commercially available artificial leathers that can be used as fibrous structures include Dinamica, manufactured by Asahi Kasei Corporation.

[0080] Examples of fiber materials suitable for a fibrous structure in a ventilation adjustment layer include polyester. The material for the ventilation adjustment layer may be one of these materials alone, or two or more may be used in combination.

[0081] The air permeability of the ventilation adjustment layer in the electrostatic electroacoustic transducer of this disclosure is 1 cm ３ / cm ２ / second over 40cm ３ / cm ２ It is less than / second. The lower limit of the air permeability of the ventilation adjustment layer of this disclosure is preferably 5 cm from the viewpoint of sound pressure. ３ / cm ２ More than 10 cm / second, more preferably 10 cm３ / cm ２ / second or more. From the perspective of high-frequency cut, the upper limit value of the air permeability of the ventilation adjustment layer of the present disclosure is preferably 35 cm ３ / cm ２ / second or less, more preferably 30 cm ３ / cm ２ / second or less. Note that the air permeability of the ventilation adjustment layer of the present disclosure is measured by the method described in the examples. It is preferable that the air permeability of the ventilation adjustment layer of the present disclosure is smaller than that of the conductive layer of the present disclosure. The conductive layer is a site that generates sound waves, and it is preferable that the air permeability is high in terms of obtaining a high sound pressure. If the air permeability of the ventilation adjustment layer arranged outside the conductive layer is smaller than that of the conductive layer, while the conductive layer contributes to a high sound pressure, the ventilation adjustment layer arranged outside the conductive layer cuts excessive high frequencies and contributes to the balance between high frequencies and low frequencies.

[0082] It is preferable that the basis weight of the ventilation adjustment layer of the present disclosure is larger than that of the sealing layer of the present disclosure. Although the sealing layer may have some high-frequency cutting ability due to its low air permeability, it tends to reduce the sound pressure. If the basis weight of the ventilation adjustment layer of the present disclosure is larger than that of the sealing layer, the influence of the sound pressure reduction by the sealing layer can be suppressed low, and the high-frequency cutting effect by the ventilation adjustment layer can be obtained well. The basis weight of the ventilation adjustment layer of the electrostatic type electroacoustic transducer of the present disclosure (when arranged on both sides of the conductive layer, the basis weight of each) is preferably 50 g / m ２ or more and 700 g / m ２ or less, more preferably 70 g / m ２ or more and 500 g / m ２ or less, and even more preferably 100 g / m ２ or more and 300 g / m ２ or less. From the perspective of sound pressure, it is preferable that the basis weight of the ventilation adjustment layer of the electrostatic type electroacoustic transducer of the present disclosure is above the above lower limit, and from the perspective of improving the sound quality balance by high-frequency cut, it is preferable that it is below the above upper limit. Note that the basis weights of the dielectric layer, conductive layer, sealing layer, and ventilation adjustment layer of the present disclosure are measured by the method described in the examples.

[0083] The electrostatic type electroacoustic transducer of the present disclosure has a sealing layer with a basis weight of 1 g / m ２ or more and 200 g / m２ as follows, and the basis weight of the ventilation adjustment layer is 50 g / m ２ or more and 700 g / m ２ or less, which is preferable.

[0084] It is preferable that the total basis weight of the sealing layer and the ventilation adjustment layer is greater than the total basis weight of the dielectric layer and the conductive layer. When the total basis weight of the sealing layer and the ventilation adjustment layer is greater than the total basis weight of the dielectric layer and the conductive layer, the effect of cutting high frequencies and shifting the sound quality to low frequencies is even better.

[0085] From the perspective of flexibility, the stiffness of the ventilation adjustment layer of the electrostatic electroacoustic transducer of the present disclosure is preferably 300 mm or less, more preferably 200 mm or less, still more preferably 100 mm or less, and particularly preferably 50 mm or less. From the perspective of ease of manufacturing or obtaining the ventilation adjustment layer, in one aspect, it may be 1 mm or more. The stiffness of the ventilation adjustment layer of the present disclosure is measured by the method described in the examples.

[0086] The thickness of the ventilation adjustment layer is not particularly limited, but may be, for example, 0.1 mm or more and 10 mm or less. The lower limit value of the thickness of the ventilation adjustment layer is, from the perspective of high-frequency cutting, for example, 0.5 mm or more, 0.8 mm or more, 1 mm or more, or 1.5 mm or more. The upper limit value of the thickness of the ventilation adjustment layer, which can be arbitrarily combined with these lower limit values, is, from the perspective of flexibility, for example, 7 mm or less, 5 mm or less, or 3 mm or less. The thickness of the ventilation adjustment layer of the present disclosure is measured by the method described in the examples. The thickness of the ventilation adjustment layer of the present disclosure is preferably greater than the thickness of the sealing layer of the present disclosure. When the thickness of the ventilation adjustment layer of the present disclosure is greater than the thickness of the sealing layer, the high-frequency cutting effect is even better.

[0087] In the electrostatic electroacoustic transducer of the present disclosure, it is preferable that the thickness of the sealing layer is 200 μm or less and the thickness of the ventilation adjustment layer is 10 mm or less.

[0088] <Buffer Layer> In addition to the conductive layer, dielectric layer, sealing layer, and ventilation adjustment layer described above, the electrostatic electroacoustic transducer may also have a buffer layer disposed on the surface opposite to the dielectric layer of one or both of the opposing pair of conductive layers. Typically, the buffer layer is disposed between the sealing layer and the conductive layer. The buffer layer is flexible and isolates the conductive layer from external people or other articles (or the sealing layer described later), while also ensuring the amplitude of the conductive and dielectric layers, thereby improving the sound pressure of the electrostatic electroacoustic transducer. The presence of a buffer layer in the electrostatic electroacoustic transducer prevents people or other articles from directly touching the conductive layer. Furthermore, when the buffer layer is present between the sealing layer and the conductive layer, it prevents the sealing layer from directly touching the conductive layer and interfering with the vibration of the conductive and dielectric layers, thus reducing noise.

[0089] The buffer layer is preferably made of a highly permeable material from the viewpoint of easily transmitting sound waves, and is preferably a fibrous structure. Examples of fibrous structures include woven fabrics, knitted fabrics, and nonwoven fabrics, and is preferably a nonwoven fabric from the viewpoint of permeability and adhesion to other layers (e.g., conductive layer or sealing layer).

[0090] From a safety standpoint, the fibrous structure of the cushioning layer is preferably composed of non-conductive fibers. Examples of non-conductive fibers include synthetic fibers and natural fibers, such as nylon, polyester (Pe), polyamide, polyvinyl alcohol, polyvinylidene chloride, polyvinyl chloride, polyacrylonitrile, polyethylene, polypropylene, polyurethane (Pu), aramid, cellulose, cotton, linen, wool, and silk. These fibers may be used individually or in combination of two or more. Examples of commercially available fibrous structures that can be used as cushioning layers include Free Cut Mesh, manufactured by Asahi Kasei Advance Corporation, product number AS255035G, "Fusion AKE64334" manufactured by Asahi Kasei Corporation, and 3D FINEX®, manufactured by Asahi Kasei Advance Corporation.

[0091] From the viewpoint of improving sound pressure and suppressing noise, the lower limit of the air permeability of the buffer layer in the electrostatic electroacoustic transducer of this disclosure is preferably 50 cm.３ / cm ２ More than 100 cm / second, more preferably 100 cm ３ / cm ２ / second or more, particularly preferably 200 cm ３ / cm ２ It is more than / second. The upper limit of the air permeability of the buffer layer is preferably 700 cm. ３ / cm ２ Less than 650 cm / second, more preferably 650 cm / second ３ / cm ２ It is less than / second. The air permeability of the buffer layer in this disclosure is measured in accordance with JIS-L-1096, 1018 air permeability test method (Method A air volume). In the measurement, the air permeability of a flexible electrostatic electroacoustic transducer is measured using the FX3300 Lab Air IV air permeability tester manufactured by Takayama Reed Co., Ltd.

[0092] <Interlayer Bonding> In the electrostatic electroacoustic transducer of this disclosure, it is preferable that at least one of the layers is bonded. The combination of layers to be bonded depends on the arrangement order of the layers in the electrostatic electroacoustic transducer. In one embodiment, it is preferable that the conductive layer and the dielectric layer are bonded. In one embodiment, it is preferable that the conductive layer and the sealing layer are bonded. In one embodiment, it is preferable that one or both of a pair of opposing conductive layers are bonded to the buffer layer. In one embodiment, it is preferable that the ventilation adjustment layer and the sealing layer are bonded. The bonding method is not particularly limited, but includes discrete bonding or continuous bonding, and discrete bonding is preferred. Here, discrete bonding means bonding that includes two or more discontinuous bonding regions (hereinafter also referred to as discrete bonding), rather than bonding consisting of a single continuous bonding region (hereinafter also referred to as continuous bonding). Although not limited to theory, it is preferable to join the ventilation adjustment layer and the sealing layer to each other in order to suppress the displacement of the ventilation adjustment layer and the sealing layer in the planar direction when the electrostatic electroacoustic transducer is deformed or when a frictional force is applied to its surface.

[0093] Examples of discrete joining methods include sewing and adhesives using non-conductive fibers, and bonding by high temperature and pressure.

[0094] Examples of threads (fibers) used for sewing include synthetic fibers and natural fibers such as polyester, polyamide, polyvinyl alcohol, polyvinylidene chloride, polyvinyl chloride, polyacrylonitrile, polyethylene, polypropylene, polyurethane, aramid, cellulose, cotton, linen, wool, and silk. These fibers may be used individually or in combination of two or more. In the case of sewing a sealing layer, it is preferable to perform post-processing (such as surface treatment) to fill the sewing holes on the surface of the sealing layer.

[0095] Examples of adhesives used for bonding include thermoplastic resins and thermosetting resins, such as acrylic, vinyl acetate, polyvinyl acetal, vinyl chloride, polyester, polyamide, cellulose, olefin, styrene, urethane, epoxy, and silicone adhesives. These adhesives may be used individually or in combination of two or more.

[0096] Bonding may be performed by hot pressing using high temperature and pressure. Hot pressing can be performed at temperatures ranging from 75°C to 150°C and pressures ranging from 0.02 MPa to 3 MPa. The hot pressing time is 3 seconds to 2 minutes.

[0097] The shape of the discrete junction may be any pattern, such as a dot pattern, stripe pattern, grid pattern, or a combination thereof. The discrete junction may consist of a single pattern across the entire region where layers face each other, or it may consist of a combination of multiple patterns.

[0098] One method of bonding is to apply an adhesive to the surface of one layer using any method, and then bond the other layer to it. Methods of applying the adhesive include intaglio printing, spraying, casting, bar coating, and application by brush. From the viewpoint of productivity, intaglio printing is preferred as the application method.

[0099] In the case of sewing, the shape of the joint corresponds to a linear shape with a constant width corresponding to the thread width when the surface of the electrostatic electroacoustic transducer is observed from the front. Therefore, discrete joints by sewing can be composed of a combination of two or more non-intersecting linear joints. The bonding area is calculated as the percentage of the area where the linear joint exists within the area where the layers face each other.

[0100] In the case of bonding, the shape of the joint corresponds to the shape of the area where the adhesive exists (the bonding area) when the surface of the electrostatic electroacoustic transducer is observed from the front. Therefore, discrete bonding by adhesive can consist of a combination of two or more discontinuous bonding areas. The bonding area is calculated as the percentage (%) of the total area of ​​the bonding area that occupies the area where the layers face each other.

[0101] In one embodiment, from the viewpoint of improving sound pressure, it is preferable that the bonding area between each layer is more than 0% and 70% or less, based on the area where the layers face each other, and more preferably 10% or more and 70% or less. In one embodiment, the ventilation adjustment layer and the sealing layer are bonded together, and it is preferable that the bonding area between each layer is more than 0% and 70% or less, based on the area where the ventilation adjustment layer and the sealing layer face each other.

[0102] Examples and comparative examples of the present disclosure are described below, but the present disclosure is not limited to the following examples and comparative examples.

[0103] <First Embodiment> <Measurement and Evaluation Method>

[0104] <Rigidity and Softness> The rigidity and softness of the buffer layer and sealing layer of the examples and comparative examples were measured in accordance with JIS-L-1096:2010, Method A (45° cantilever method). A 45° cantilever type testing machine was used for the measurements. Here, if the rigidity and softness of the samples in each example were high, measurements were taken by extending the sample while maintaining the inclination angle of the inclined surface and by extending the sample on the horizontal surface.

[0105] <Air Permeability> The air permeability of the buffer layer and sealing layer of the examples and comparative examples was measured in accordance with JIS-L-1096, 1018 air permeability test method (Method A: air volume). In the measurement, the air permeability transmitted through a flexible electrostatic electroacoustic transducer was measured using the FX3300 Lab Air IV air permeability tester manufactured by Takayama Reed Co., Ltd.

[0106] <5% Compression Load> The cushioning material layers of the examples and comparative examples were compressed at a speed of 5 mm / second using a φ3.5 circular compressor on a KES-G5 compression testing machine manufactured by Kato Tech Co., Ltd. The compression load was measured when 5% of the total thickness, which is the shortest side of the cushioning material layer, was compressed.

[0107] <Dielectric Breakdown Voltage> The sealing layer (5 cm x 5 cm) of the examples and comparative examples was measured in accordance with JIS C 2110-1. A DC voltage was applied using a dielectric strength tester (TOS5101, manufactured by Kikusui Electronics Co., Ltd.), the current was checked after 20 seconds, and the voltage was gradually increased to measure the voltage at which breakdown occurred.

[0108] <Water Resistance> Water resistance tests were conducted on each sealing layer of the examples and comparative examples in accordance with JIS L 1092 A method (low water pressure method).

[0109] <Moisture Permeability> Moisture permeability tests were conducted on each sealing layer of the examples and comparative examples in accordance with JIS L 1099.

[0110] <Peel Strength> In the cushioning layer and conductive layer of the examples and comparative examples, peel adhesion strength tests were conducted in accordance with JIS L 1086.

[0111] <Sound Pressure> In a room measuring 4m x 4m x 2m (25°C, 40% RH), a pure tone of 2000 Hz was reproduced from an electrostatic electroacoustic transducer (10cm x 10cm) suspended at a height of 1m, and the sound pressure was measured at a distance of 1m from the electrostatic electroacoustic transducer. The sound pressure of the electrostatic electroacoustic transducer of Comparative Example 1 (P ０ For (dB), the sound pressure (P) of each electrostatic electroacoustic transducer １ ) (dB) difference (=P １ -P ０ The (dB) level was measured.

[0112] <Noise> In a room measuring 4m x 4m x 2m (25°C, 40% RH), an electrostatic electroacoustic transducer (10cm x 10cm) was suspended at a height of 1m and a pure tone of 2000Hz was reproduced. At this time, monitors seated 1m away from the electrostatic electroacoustic transducer were asked to subjectively evaluate the clarity of the sound on the following five-point scale, and the average value was used as the evaluation result. There were eight monitors. 5: A considerable noise reduction effect is felt. 4: A noise reduction effect is felt. 3: A slight noise reduction effect is felt. 2: A slight noise reduction effect is felt. 1: No noise reduction effect is felt.

[0113] <Sound Generation After Friction Test> For each electrostatic electroacoustic transducer in the examples and comparative examples, a test specimen measuring 70 mm in width and 300 mm in length was prepared. The test specimen was placed on the flat abrasion table of the testing machine (flat abrasion machine, Daiei Kagaku Seiki Seisakusho, product number PA-300A), with the surface of the test specimen facing upwards and without wrinkles, and secured with a clamp. Next, a friction element fitted with JIS L 3102 (cotton canvas) No. 6 cotton canvas was placed on top of the test specimen. A test was performed for 1000 reciprocations with a pressing load of 9.81 N {1 kgf} including the friction element, a stroke of 140 mm, and a speed of 60 ± 10 reciprocations / min. After the test, when a 2000 Hz pure tone was reproduced through the wiring of the electrostatic electroacoustic transducer, it was judged as "○" if sound was generated and "×" if no sound was generated.

[0114] Examples and Comparative Examples <Example 1A> Nonwoven fabric as the fiber structure (Presize®, manufactured by M.A. Life Materials Co., Ltd., model number AC1050, basis weight 50 g / m²) ２Using a ) material, aluminum was deposited on one side as a conductive material-containing layer of the conductive layer to obtain a conductive layer. A pair of conductive layers were placed facing each other with the sides without the conductive material-containing layer facing inward, and a 30 μm thick, 120 mm square electret film made of a fluoropolymer (Poreflon® Mebren, manufactured by Sumitomo Electric Fine Polymer Co., Ltd., product number HP-010-30) was sandwiched between them as a dielectric layer so as to be in contact with the conductive layer. At this time, an acrylic adhesive was applied in a stripe pattern to the surface of the dielectric layer, and then the conductive layer was bonded to it to obtain a conductive layer-dielectric layer-conductive layer laminate. The conductive layer-dielectric layer-conductive layer laminate was punched out to a 100 mm square, and wiring was connected to the conductive material-containing layer of each pair of conductive layers. Acrylic adhesive was applied in a dot pattern to the conductive layer surface, sandwiching the pair of buffer layers (Free Cut Mesh, manufactured by Asahi Kasei Advance Co., Ltd., part number AS255035G) so that they could be placed on the surfaces of both conductive layers opposite to the dielectric layer. Next, a pair of encapsulating layers (ester-based polyurethane resin film, manufactured by Nisshinbo Textile Co., Ltd., Mobilon Film MF100T) were placed on the surface of the buffer layer opposite to the conductive layer and bonded by hot pressing (temperature 120°C, pressure 0.02 MPa and time 20 seconds) to obtain a flexible electrostatic electroacoustic transducer consisting of an encapsulating layer-buffering layer-conductor layer-dielectric layer-conductor layer-buffering layer-encapsulating layer laminate (see Figure 1).

[0115] The joint between the buffer layer and the conductive layer was bonded in a dot shape using adhesive, and the bonding area between each layer was made to be 50% based on the area where the conductive layer and the buffer layer face each other. That is, as schematically shown in Figure 2, a dot-shaped adhesive with a diameter of Φ16 mm was applied in a 5x5 grid pattern. Starting from both ends of the electrostatic electroacoustic transducer, 4 mm was left unbonded, and the bonding was carried out in a 5x5 grid pattern of bonded Φ16 mm - unbonded 3 mm. In Figure 2, arrow 20 indicates the transport direction in the manufacturing process of the electrostatic electroacoustic transducer 10, with the colorless area indicating the unbonded area 5 and the gray area indicating the bonded area 6. The same applies to Figure 3. The joint between the buffer layer and the sealing layer was bonded in a stripe shape using a hot press. As schematically shown in Figure 3, the starting point of the hot press was bonded from both ends of the electrostatic electroacoustic transducer in a pattern of bonded 10 mm - unbonded 12.5 mm to the end. Based on the area where the sealing layer and the buffer layer face each other, the product was manufactured so that the bonding area between each layer was 50%.

[0116] <Example 2A> A flexible electrostatic electroacoustic transducer was obtained in the same manner as in Example 1, except that a buffer layer was formed by coating a mesh-like material made from molten polyurethane resin onto the conductive layer using intaglio printing, the bonding area between each layer was 80% based on the area where the conductive layer and the buffer layer face each other, and the bonding area between each layer was 80% based on the area where the sealing layer and the buffer layer face each other.

[0117] <Example 3A> A flexible electrostatic electroacoustic transducer was obtained in the same manner as in Example 1, except that the cushioning layer was changed to a three-dimensional knitted fabric (Fusion AKE64334 manufactured by Asahi Kasei Corporation).

[0118] <Example 4A> The cushioning layer is made of three-dimensional knitted fabric (3D FINEX®, manufactured by Asahi Kasei Advance Co., Ltd., weight 330 g / m²) ２ A flexible electrostatic electroacoustic transducer was obtained in the same manner as in Example 1, except that the material was changed to 62% polyester (Pe) and 38% polyurethane (Pu).

[0119] <Example 5A> A flexible electrostatic electroacoustic transducer was obtained in the same manner as in Example 1, except that the sealing layer was changed to an ester-based polyurethane resin film (Mobilon Film MF50T-1470, manufactured by Nisshinbo Textile Co., Ltd.).

[0120] <Example 6A> A flexible electrostatic electroacoustic transducer was obtained in the same manner as in Example 1, except that the sealing layer was changed to natural rubber (ultra-thin amber rubber sheet (amber crepe), manufactured by Fuso Rubber Industry Co., Ltd., product number 12986-0005-7).

[0121] <Example 7A> A flexible electrostatic electroacoustic transducer was obtained in the same manner as in Example 3, except that the sealing layer was processed with a needle punch to create holes, the bonding area between each layer was made to be 30% based on the area where the conductive layer and the buffering layer face each other, and the bonding area between each layer was made to be 30% based on the area where the sealing layer and the buffering layer face each other.

[0122] <Example 8A> A flexible electrostatic electroacoustic transducer was obtained in the same manner as in Example 1, except that a silicone coating was applied to the conductive layer side of the buffering material layer, and the peel strength between the buffering material layer and the conductive layer was set to 0.11 N / cm.

[0123] <Comparative Example 1A> A flexible electrostatic electroacoustic transducer was obtained in the same manner as in Example 1, except that it did not contain a buffering layer.

[0124] <Comparative Example 2A> A flexible electrostatic electroacoustic transducer was obtained in the same manner as in Example 1, except that the cushioning layer was changed to a polypropylene (PP) board (polypropylene plate, AS ONE Corporation, product number 64-6378-83).

[0125] <Comparative Example 3A> A flexible electrostatic electroacoustic transducer was obtained in the same manner as in Example 1, except that the sealing layer was changed to a polypropylene (PP) board (polypropylene plate, AS ONE Corporation, product number 64-6378-83).

[0126]

[0127] ≪Second Embodiment≫ 《Measurement and Evaluation Method》 〈Rigidity〉 The rigidity of the ventilation adjustment layers of the examples and comparative examples was measured in accordance with JIS-L-1096:2010, Method A (45° cantilever method). A 45° cantilever type testing machine was used for the measurement. Here, if the rigidity of the samples of each example was high, the measurement was taken by extending the inclined surface while maintaining the inclination angle, and by extending the horizontal surface.

[0128] <Air Permeability> The air permeability of the permeability adjustment layer and sealing layer of the examples and comparative examples was measured in accordance with JIS-L-1096, 1018 air permeability test method (Method A: air volume). In the measurement, the air permeability transmitted through a flexible electrostatic electroacoustic transducer was measured using the Takayama Reed Co., Ltd. air permeability tester FX3300 Lab Air IV.

[0129] <Basis Weight> The basis weight of the dielectric layer, conductive layer, sealing layer, and ventilation adjustment layer of the examples and comparative examples was measured in accordance with JIS L 1913.

[0130] <Thickness> The dielectric layer, conductive layer, sealing layer, and ventilation adjustment layer of the examples and comparative examples were measured in accordance with JIS L1913 Method B. The thickness (μm) was measured at three or more locations at a pressure of 0.02 kPa, and the average value was calculated.

[0131] <Dielectric Breakdown Voltage> The sealing layer (5 cm x 5 cm) of the examples and comparative examples was measured in accordance with JIS C 2110-1. A DC voltage was applied using a dielectric strength tester (TOS5101, manufactured by Kikusui Electronics Co., Ltd.), the current was checked after 20 seconds, and the voltage was gradually increased to measure the voltage at which breakdown occurred.

[0132] <Sound pressure> Conductive layer: Copper-plated fabric (U5001W, manufactured by Urase Co., Ltd., weight 75 g / m) ２ Air permeability 40 cc / cm ２A dielectric (P) was used. Between a pair of conductive layers, a 50 μm thick, 120 mm square silicone film (Maxell Kureha Co., Ltd.: SC50NNK) made of silicone polymer was sandwiched as a dielectric layer so as to be in contact with the conductive layers. At this time, an acrylic adhesive was applied in a stripe pattern to the surface of the dielectric layer, and then the conductive layer was bonded to it to obtain a conductive layer-dielectric layer-conductive layer laminate. The conductive layer-dielectric layer-conductive layer laminate was punched out to a 100 mm square, and wiring was connected to each of the two conductive layers to obtain a flexible electrostatic electroacoustic transducer to be used as a measurement reference. In a room measuring 4 m x 4 m x 2 m (25°C, 40% RH), a pure tone of 1000 Hz was reproduced from an electrostatic electroacoustic transducer (10 cm x 10 cm) suspended at a height of 1 m, and the sound pressure was measured at a distance of 1 m from the electrostatic electroacoustic transducer. The sound pressure (P) of the electrostatic electroacoustic transducer that served as the measurement reference was measured. ０ For (dB), the sound pressure (P) of each electrostatic electroacoustic transducer １ ) (dB) difference (=P ０ -P １ The sound pressure was measured in dB. The following standards were used for sound pressure: E (Excellent): P ０ -P １ ≦5dB, G (acceptable): 5dB<P ０ -P １ ≦10dB, P (not allowed): P ０ -P １ >Evaluated at 10dB.

[0133] <Frequency Balance> In a room measuring 4m x 4m x 2m (25°C, 40% RH), a pure tone of 5000 Hz was reproduced from an electrostatic electroacoustic transducer (10cm x 10cm) suspended at a height of 1m, and the sound pressure was measured at a distance of 1m from the electrostatic electroacoustic transducer. Furthermore, the sound pressure was measured at a distance of 1m from the electrostatic electroacoustic transducer under the same conditions as above, except that a pure tone of 500 Hz was reproduced. The sound pressure (P) of the electrostatic electroacoustic transducer that served as the measurement standard in the above <Sound Pressure> test was measured. ０’ For (dB), the sound pressure (P) of each electrostatic electroacoustic transducer １’ ) (dB) difference (=P ０’ -P １’ The sound pressure was measured in dB. The following standard was used for the P in the 500 Hz band. ０’ -P １’The noise level is 5 dB or less, and in the 5000 Hz band, 10 dB ≤ P ０’ -P １’ <30dB is E (Excellent), P in the 500Hz band ０’ -P １’ The noise level is 5 dB or less, and in the 5000 Hz band, 5 dB ≤ P ０’ -P １’ <If it is 10 dB, it is G (acceptable), and in the 5000 Hz band, P ０’ -P １’ A level of 5 dB was evaluated as P (unacceptable).

[0134] Examples and Comparative Examples Example 1: Copper-plated fabric (U5001W, manufactured by Urase Co., Ltd., basis weight 75 g / m) as the conductive layer. ２ Using a pair of conductive layers, a 50 μm thick, 120 mm square silicone film (Maxell Kureha Corporation: SC50NNK, basis weight 75 g / m²) made of silicone polymer is placed between the conductive layers as a dielectric layer so as to be in contact with the conductive layers. ２ A conductive layer and a dielectric layer were sandwiched together. At this time, acrylic adhesive was applied in a striped pattern between the conductive layer and the dielectric layer to bond them, resulting in a weight (total basis weight of dielectric and conductive layers) of 225 g / m². ２ A laminate of conductive layer-dielectric layer-conductive layer was obtained. The laminate of conductive layer-dielectric layer-conductive layer was punched out into 100 mm squares, and wiring was connected to the conductive material-containing layers of each pair of conductive layers. Furthermore, acrylic adhesive was applied in a striped pattern to both sides of the pair of conductive layers opposite to the dielectric layer so that the generated sound pressure could pass through, and a 150 mm square polyurethane film (Mobilon®, manufactured by Nisshinbo Textile Co., Ltd., product number MF100T, 100 μm thick) was bonded as a sealing layer. Next, acrylic adhesive was applied in a striped pattern to one side of the pair of sealing layers opposite to the dielectric layer so that the adhesive area was 70%, and a 150 mm square artificial leather (Dinamica®, manufactured by Asahi Kasei Corporation, basis weight: 290 g / m²) was bonded as a breathability adjustment layer. ２ By bonding these together, a flexible electrostatic electroacoustic transducer was obtained.

[0135] The sealing layer and the ventilation adjustment layer were bonded together using an adhesive to create a striped pattern. The bonding started from both ends of the electrostatic electroacoustic transducer, with a pattern of 7 mm bonded - 3 mm unbonded, extending to the end. Based on the area where the sealing layer and the ventilation adjustment layer face each other, the bonding area between each layer was fabricated to be 70%.

[0136] <Example 2> Polyester knitted fabric as a breathability adjustment layer (prototype, weight 314 g / m) ２ A flexible electrostatic electroacoustic transducer was obtained in the same manner as in Example 1, except that 100% Pe was used.

[0137] <Example 3> Plain weave polyester fabric as a breathability adjustment layer (prototype, weight 298 g / m²) ２ A flexible electrostatic electroacoustic transducer was obtained in the same manner as in Example 1, except that 100% Pe was used.

[0138] <Example 4> A polyurethane film (ESMAR® URS, manufactured by Nippon Matai Co., Ltd., 50 μm thick) was used as the sealing layer, and a spunbond-meltblown-spunbond (SMS) type nonwoven fabric (Presize®, manufactured by Asahi Kasei Corporation, model number C5210, basis weight 70.5 g / m²) was used as the breathability adjustment layer. ２ A flexible electrostatic electroacoustic transducer was obtained in the same manner as in Example 1, except that a material with a thickness of 0.23 mm was used, and the bonding area between the sealing layer and the ventilation adjustment layer was 10%, and the acrylic adhesive was applied in a stripe pattern from both ends of the electrostatic electroacoustic transducer to the end in a pattern of 1 mm bonded - 9 mm unbonded.

[0139] <Example 5> A flexible electrostatic electroacoustic transducer was obtained in the same manner as in Example 3, except that a polyurethane film (Mobilon®, manufactured by Nisshinbo Textile Co., Ltd., product number MF200T, 200 μm thick) was used as the sealing layer.

[0140] <Example 6> As a breathability adjustment layer, an SMS type nonwoven fabric (Presize®, manufactured by Asahi Kasei Corporation, model number A1120, basis weight 20 g / m²) was used. ２ A flexible electrostatic electroacoustic transducer was obtained in the same manner as in Example 1, except that a material with a thickness of 0.14 mm was used.

[0141] <Example 7> A flexible electrostatic electroacoustic transducer was obtained in the same manner as in Example 3, except that a pair of buffer material layers (Free Cut Mesh, manufactured by Asahi Kasei Advance Corporation, part number AS255035G) were placed on the surfaces of both conductive layers opposite to the dielectric layer, and that the pair of buffer material layers were bonded by sandwiching them between acrylic adhesive applied in a dot pattern on the surface of the conductive layer. The electrostatic electroacoustic transducer of Example 7 is a laminate (see Figure 4) having the following arrangement in this order: ventilation adjustment layer - sealing layer - buffer material layer - conductive layer - dielectric layer - conductive layer - buffer material layer - sealing layer - ventilation adjustment layer.

[0142] <Comparative Example 1> Plain weave polyester fabric as a breathability adjustment layer (prototype, weight 149 g / m²) ２ A flexible electrostatic electroacoustic transducer was obtained in the same manner as in Example 1, except that 100% Pe was used.

[0143] <Comparative Example 2> A flexible electrostatic electroacoustic transducer was obtained in the same manner as in Example 3, except that an SMS-type nonwoven fabric (Presize®, manufactured by Asahi Kasei Corporation, model number C5210, basis weight 70.5 g / m2, thickness 0.23 mm) was used as the sealing layer. The dielectric breakdown voltage of Comparative Example 2 was 3 kV or less, so it was not sufficient as a measure against electric shock when high voltage was applied to the electrostatic electroacoustic transducer.

[0144]

[0145] 1. Dielectric layer 2. Conductive layer 3. Cushioning layer 4. Sealing layer 5. Non-bonding region 6. Bonding region 7. Ventilation adjustment layer 10. Electrostatic electroacoustic transducer 20. Conveying direction

Claims

1. A flexible electrostatic electroacoustic transducer having a pair of opposing conductive layers and a dielectric layer disposed between the pair of opposing conductive layers, wherein the electrostatic electroacoustic transducer further comprises: a flexible buffer layer disposed on the surface of one or both of the pair of opposing conductive layers opposite to the dielectric layer; and a flexible sealing layer disposed on the surface of the buffer layer opposite to the conductive layer.

2. The electrostatic electroacoustic transducer according to claim 1, wherein the buffer layer and the conductive layer are bonded together, and the peel strength between the buffer layer and the conductive layer is 0.15 N / cm or more.

3. The electrostatic electroacoustic transducer according to claim 1 or 2, wherein the sealing layer and the cushioning layer are joined together.

4. The electrostatic electroacoustic transducer according to claim 1 or 2, wherein the bonding area between each layer is less than 100% based on the area where the sealing layer and the cushioning material layer face each other.

5. The electrostatic electroacoustic transducer according to claim 1 or 2, wherein the bonding area between each layer is less than 100% based on the area where the buffer layer and the conductive layer face each other.

6. The electrostatic electroacoustic transducer according to claim 1 or 2, wherein the buffer layer and the sealing layer are disposed on both surfaces of the pair of opposing conductive layers, respectively.

7. The electrostatic electroacoustic transducer according to claim 1 or 2, wherein the rigidity of the cushioning layer is 300 mm or less.

8. The air permeability of the cushioning layer is 30 cm ３ / cm ２ The electrostatic electroacoustic transducer according to claim 1 or 2, wherein the frequency is 1 / second or more.

9. The compression load of the cushioning material layer is 40 gf / cm². ２ The electrostatic electroacoustic transducer according to claim 1 or 2, which is as follows:

10. The electrostatic electroacoustic transducer according to claim 1 or 2, wherein the buffer layer is formed on the conductive layer by coating.

11. A flexible electrostatic electroacoustic transducer having a pair of opposing conductive layers, a dielectric layer disposed between the pair of opposing conductive layers, a sealing layer, and a ventilation adjustment layer, wherein the sealing layer and the ventilation adjustment layer are disposed on one or both of the pair of opposing conductive layers on the side opposite to the dielectric layer, and the air permeability of the sealing layer is 0 cm ３ / cm ２ / second or more and 1 cm ３ / cm ２ / second or less, and the air permeability of the ventilation adjustment layer is more than 1 cm ３ / cm ２ / second and 40 cm ３ / cm ２ / second or less, the electrostatic electroacoustic transducer.

12. The electrostatic electroacoustic transducer according to claim 11, comprising the dielectric layer, the conductive layer, the sealing layer, and the ventilation adjustment layer in this order.

13. The electrostatic electroacoustic transducer according to claim 11 or 12, wherein the basis weight of the ventilation adjustment layer is greater than the basis weight of the sealing layer.

14. The basis weight of the sealing layer is 1 g / m². ２ More than 200g / m ２ The following conditions apply, and the basis weight of the ventilation adjustment layer is 50 g / m². ２ 700g / m or more ２ The electrostatic electroacoustic transducer according to claim 11, which is as follows:

15. The electrostatic electroacoustic converter according to claim 13, wherein the sum of the basis weights of the sealing layer and the ventilation adjustment layer is greater than the sum of the basis weights of the dielectric layer and the conductive layer.

16. The electrostatic electroacoustic transducer according to claim 11 or 12, wherein the degree of permeability of the permeability adjustment layer is less than the degree of permeability of the conductive layer.

17. The electrostatic electroacoustic transducer according to claim 11 or 12, wherein the thickness of the ventilation adjustment layer is greater than the thickness of the sealing layer.

18. The electrostatic electroacoustic transducer according to claim 16, wherein the thickness of the sealing layer is 200 μm or less, and the thickness of the ventilation adjustment layer is 10 mm or less.

19. The electrostatic electroacoustic transducer according to claim 11 or 12, wherein the ventilation adjustment layer and the sealing layer are bonded together, and the bonding area between each layer, based on the area where the ventilation adjustment layer and the sealing layer face each other, is greater than 0% and less than or equal to 70%.

20. The electrostatic electroacoustic transducer according to claim 11, further comprising a buffer layer disposed on the surface of one or both of the opposing pair of conductive layers opposite to the dielectric layer.

21. The electrostatic electroacoustic transducer according to claim 20, comprising the dielectric layer, the conductive layer, the buffer layer, the sealing layer, and the ventilation adjustment layer in this order.

22. The electrostatic electroacoustic transducer according to claim 1 or 11, wherein the rigidity of the sealing layer is 300 mm or less.

23. The electrostatic electroacoustic converter according to claim 1 or 11, wherein the dielectric breakdown voltage of the sealing layer is 3 kV or more.

24. The electrostatic electroacoustic transducer according to claim 1 or 11, wherein the water resistance of the sealing layer is 200 mm or more.

25. The moisture permeability of the sealing layer is 400 g / m². ２ - An electrostatic electroacoustic transducer according to claim 1 or 11, wherein h is less than or equal to h.

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