JP5694877B2 - Polymer speaker - Google Patents

Description

  The present invention relates to a polymer speaker using an electrostrictive element as a vibration member.

  As a speaker that converts an electric signal into sound, a dynamic speaker unit is known. The dynamic speaker unit includes a permanent magnet, a voice coil, a diaphragm, and the like. According to the dynamic speaker unit, the sound phase is reversed between the front side and the rear side of the diaphragm. For this reason, when the sound emitted from the rear turns around to the front, the front sound and the rear sound cancel each other, resulting in a small sound. Therefore, the dynamic speaker unit is used in a state where it is incorporated in the enclosure in order to block the sound coming out from the rear from wrapping forward. In this case, it is necessary to prevent the movement of the diaphragm from being hindered by the air in the enclosure. Therefore, the enclosure tends to be large.

  On the other hand, Patent Documents 3 and 4 disclose transducers configured by arranging a pair of electrodes on both front and back surfaces of an elastomeric dielectric film. In this type of transducer, when the voltage applied between the electrodes is increased, the electrostatic attractive force between the electrodes is increased, and the dielectric film sandwiched between the electrodes is compressed in the thickness direction. Thereby, the thickness of the dielectric film is reduced. As the film thickness decreases, the dielectric film extends in the plane direction accordingly. On the other hand, when the voltage applied between the electrodes is reduced, the electrostatic attractive force between the electrodes is reduced, so that the compressive force on the dielectric film is reduced. For this reason, the film thickness of a dielectric film becomes thick. As the film thickness increases, the dielectric film shrinks in the surface direction accordingly. The transducer can be used as a speaker by utilizing the change in the thickness of the dielectric film with respect to voltage.

Japanese Utility Model Publication No. 60-111195 JP 2007-312094 A JP-T-2001-524278 JP 2011-72112 A

  According to the transducer, the dielectric film is vibrated by the change in film thickness, and sounds are generated from both the front and back surfaces of the dielectric film. The phase of the generated sound is the same on the front side and the back side of the dielectric film. For this reason, unlike the conventional dynamic speaker unit, even if the sound emitted from the back side wraps around to the front side, they do not cancel each other. Therefore, when the transducer is used as a speaker, an enclosure is not necessary.

  However, the transducer has the following problems. That is, when the transducer is used as a speaker, an alternating voltage as a sound electric signal is superimposed with a bias voltage applied to the dielectric film. When a bias voltage is applied, the thickness of the dielectric film decreases and the dielectric film extends in the surface direction. At this time, the dielectric film may be wrinkled as much as the dielectric film extends. When an AC voltage is superimposed in a state where wrinkles are generated, the dielectric film cannot vibrate uniformly, and divided vibration is likely to occur. When divided vibration occurs, the phase of the sound does not match between the front side and the back side of the dielectric film. And it becomes difficult to make a sound by canceling out the emitted sound waves.

  In this regard, for example, if the dielectric film is arranged in advance in the plane direction, generation of wrinkles due to application of a bias voltage can be suppressed. However, when the elastomer dielectric film is held in a stretched state, there is a problem that it is easy to sag. When the dielectric film falls, it cannot vibrate and the sound pressure decreases. Also, if the dielectric film is hardened, wrinkles are less likely to occur. However, if the dielectric film is hard, it is difficult to vibrate. For this reason, speaker performance falls. In this case, there is a possibility that sound in a high frequency region is difficult to be emitted.

  The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a polymer speaker that is not easily wrinkled even when a bias voltage is applied and has excellent durability.

  (1) In order to solve the above-described problem, a polymer speaker of the present invention includes a vibration member including a dielectric film made of an elastomer or a resin, and a plurality of electrodes arranged via the dielectric film, and the vibration member. It is characterized by comprising a foam layer disposed on both front and back surfaces and a frame for supporting a peripheral portion of the vibration member.

  In the polymer speaker of the present invention, when an alternating voltage as an electric signal of sound is applied between the electrodes, the thickness of the dielectric film changes according to the electrostatic attractive force between the electrodes. When the dielectric film vibrates due to the change in film thickness, sound is generated from both the front and back surfaces of the vibration member. Here, foam layers are disposed on both the front and back surfaces of the vibration member. The foam layer restricts deformation in the surface direction of the vibration member. And the rigidity in the surface direction of a vibration member becomes large. Thereby, generation | occurrence | production of the wrinkle of the dielectric film at the time of bias voltage application is suppressed. On the other hand, the foam layer is flexible. Therefore, it is difficult to inhibit deformation of the vibration member in the thickness direction (front and back direction). That is, the vibration of the vibration member for generating sound is not easily inhibited. As described above, according to the polymer speaker of the present invention, it is possible to suppress the generation of wrinkles of the dielectric film when the bias voltage is applied while ensuring the original function of the vibration member. As a result, the divided vibration is suppressed, and a wide frequency range sound can be generated.

  The vibration member includes an elastomer or resin dielectric film and an electrode. For this reason, the polymer speaker of the present invention is thinner and lighter than a conventional dynamic speaker unit having a permanent magnet or a voice coil. Moreover, it can be manufactured at a relatively low cost. Furthermore, the polymer speaker of the present invention does not require an enclosure. Therefore, the polymer speaker of the present invention is lightweight, easy to miniaturize, and relatively inexpensive. “Elastomer or resin” means that the base material of the dielectric film is an elastomer or a resin. Therefore, in addition to the elastomer or the resin component, other components such as additives may be included. Elastomers include rubber and thermoplastic elastomers.

  (2) Preferably, in the configuration of (1) above, the foam layer is preferably an open cell structure.

  A large number of bubbles are present inside the foam layer. For example, when individual bubbles are independent (that is, when the foam layer is a closed cell), the foam layer may function as an air spring by acting like an elastic body. In this case, the foam layer may hinder the movement of the vibration member, and the speaker performance may be reduced. This phenomenon becomes remarkable in vibrations in a high frequency region. On the other hand, the foam layer of this structure is an open-cell body. That is, the individual bubbles are connected to each other. For this reason, the gas in a foam layer tends to escape. Therefore, the foam layer is less likely to be an air spring, and the movement of the vibration member is less likely to be hindered. Therefore, the speaker performance is unlikely to deteriorate. The foam layer of the open cell body may be manufactured by adjusting the raw material composition or by performing a communication treatment such as air crushing after foam molding. Moreover, you may adjust the communication form of a bubble, such as making a bubble communicate in a thickness direction.

  (3) Preferably, in the configuration of (2) above, the foam layer may have a ventilation rate of 1000 ml / min or more.

  In this configuration, the bubbles in the foam layer are sufficiently communicated. Therefore, the gas in the foam layer is easy to escape. Therefore, the foam layer is less likely to be an air spring, and the movement of the vibration member is less likely to be hindered.

  As the air flow rate, a value measured by the following method is adopted. That is, first, a flat vent jig is prepared. A ventilation hole with a diameter of 60 mm is provided at the center of the ventilation jig. Next, one surface of the sample of the foam layer (length 75 mm × width 75 mm × thickness 10 mm) is pressed with a ventilation jig. In this state, the other surface opposite to one surface of the sample is sucked under reduced pressure by an intake pump. At this time, the differential pressure on both sides is set to 98 Pa. Then, the flow rate of the air guided to the intake pump is measured with a flow meter.

  (4) Preferably, in any one of the constitutions (1) to (3), the foam layer is preferably composed of urethane foam.

  In the case of urethane foam, desired physical properties are easily realized by adjusting the raw material composition and manufacturing conditions. Also, it is easy to manufacture and relatively inexpensive. Therefore, according to this configuration, the polymer speaker of the present invention is easily put into practical use.

  (5) Preferably, in any one of the constitutions (1) to (4), the dielectric film is made of an elastomer.

  If the vibration member is inflexible, it is difficult to vibrate against the applied voltage in the low frequency region. Therefore, there is a risk that it is difficult to produce sound in the low frequency region. In this respect, the elastomer is flexible and excellent in elasticity. Therefore, according to this configuration, the vibrating member easily vibrates even with an applied voltage in a low frequency region. Therefore, it is possible to generate a sound in a low frequency region. The elastomer is flexible and easily deformed. For this reason, when the dielectric film is made of an elastomer, divided vibration is likely to occur with respect to an applied voltage in a high frequency region. However, as described above, the foam layers are disposed on both the front and back surfaces of the vibration member. Therefore, the rigidity in the surface direction of the vibration member is large. Thereby, even if the dielectric film is made of an elastomer, the divided vibration in the high frequency region can be suppressed.

  (6) Preferably, in any one of the configurations (1) to (5), the electrode is preferably made of a flexible conductive material including an elastomer and a conductive material.

  The electrodes are arranged on both the front and back surfaces of the dielectric film. An electrode formed of a flexible conductive material including an elastomer is flexible and can expand and contract integrally with a dielectric film. For this reason, it is difficult to inhibit the movement of the dielectric film. In addition, when the dielectric film is made of an elastomer, both the dielectric film and the electrode are flexible, so that it is easier to generate sound in the low frequency region. Further, even if the vibration is repeated, the electrode is difficult to peel from the dielectric film. Therefore, the vibration member of this configuration is excellent in durability.

  (7) Preferably, in any one of the configurations (1) to (6), the vibration member includes a plurality of the dielectric films, and the dielectric films and the electrodes are alternately stacked. Is better.

  The number of dielectric films and electrodes constituting the vibrating member is not particularly limited. For example, electrodes may be arranged on both surfaces of one dielectric film. According to this configuration, the vibration member has a plurality of dielectric films. Thereby, the deformation amount of the vibration member with respect to the applied voltage is increased, and the output sound pressure can be increased.

It is a perspective view of the polymer speaker of an embodiment. It is II-II sectional drawing of FIG.

  Hereinafter, embodiments of the polymer speaker of the present invention will be described.

[Configuration of polymer speaker]
First, the configuration of the polymer speaker of this embodiment will be described. FIG. 1 shows a perspective view of the polymer speaker of the present embodiment. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. In FIG. 1, the foam layer on the front side (front side) is shown through. As shown in FIGS. 1 and 2, the polymer speaker 1 includes a vibration member 10, a front side foam layer 20a, a back side foam layer 20b, a front side frame 30a, and a back side frame 30b.

  The front side frame 30a and the back side frame 30b are each made of resin and have a ring shape. The front side frame 30a and the back side frame 30b are disposed to face each other with the peripheral portions of the vibration member 10, the front side foam layer 20a, and the back side foam layer 20b interposed therebetween. The front side frame 30 a and the back side frame 30 b are fixed by eight bolts 31 and eight nuts 32. The set of “bolts 31 and nuts 32” are arranged at predetermined intervals in the circumferential direction of the polymer speaker 1. The bolt 31 penetrates from the front surface of the front frame 30a to the rear surface of the back frame 30b. The nut 32 is screwed to the penetrating end of the bolt 31. The front side frame 30a and the back side frame 30b are included in the frame in the present invention.

  The front-side foam layer 20a is made of polyurethane foam and has a circular plate shape. The polyurethane foam is an open cell body with an air flow rate of 1200 ml / min. The front-side foam layer 20 a is disposed so as to cover the front surface (surface) of the vibration member 10. The back side foam layer 20b is also made of a polyurethane foam similar to the front side foam layer 20a, and has a circular plate shape. The back side foam layer 20b is disposed so as to cover the rear surface (back surface) of the vibration member 10. The front side foam layer 20a and the back side foam layer 20b are included in the foam layer in the present invention.

  The vibration member 10 is interposed between the front side frame 30a and the back side frame 30b via the front side foam layer 20a and the back side foam layer 20b. The vibration member 10 includes three dielectric films 11a to 11c and four electrodes 12a to 12d. In the vibration member 10, the dielectric films 11a to 11c and the electrodes 12a to 12d are alternately stacked.

  The dielectric films 11a to 11c are all made of hydrogenated nitrile rubber (H-NBR) and have a circular thin film shape. Each of the electrodes 12a to 12d is made of a flexible conductive material in which silver powder is filled in silicone rubber. Each of the electrodes 12a to 12d has a circular thin film shape having a smaller diameter than the dielectric films 11a to 11c. The electrodes 12a to 12d are disposed substantially concentrically with the dielectric films 11a to 11c, respectively. The electrodes 12a to 12d have terminal portions 120a to 120d, respectively. The terminal portions 120a to 120d protrude from the outer peripheral edge above the electrodes 12a to 12d in the diameter increasing direction, respectively. Each of the terminal portions 120a to 120d has a strip shape. A voltage is applied to the terminal portions 120a to 120d from the outside via wiring (not shown).

[Method of manufacturing polymer speaker]
Next, the manufacturing method of the polymer speaker of this embodiment is demonstrated. First, the dielectric films 11a to 11c are prepared. Next, a coating material containing a flexible conductive material is printed on both the front and back surfaces of the dielectric film 11a to form the electrodes 12a and 12b. Similarly, a paint containing a flexible conductive material is printed on both the front and back surfaces of the dielectric film 11c to form the electrodes 12c and 12d. Then, the dielectric film 11a on which the electrodes 12a and 12b are formed, the dielectric film 11b, and the dielectric film 11c on which the electrodes 12c and 12d are formed are laminated to produce the vibration member 10.

  Next, the front-side foam layer 20a is attached to the surface of the vibration member 10, and the back-side foam layer 20b is attached to the back surface with an adhesive. And the peripheral part of the produced laminated body is clamped by the front side frame 30a and the back side frame 30b. In this state, the front side frame 30 a and the back side frame 30 b are fixed by the eight bolts 31 and the eight nuts 32. In this way, the polymer speaker 1 is manufactured.

[Polymer speaker movement]
Next, the movement of the polymer speaker of this embodiment will be described. In an initial state, a predetermined bias voltage is applied to the electrodes 12a to 12d via a wiring (not shown). In this state, an alternating voltage as a sound electric signal is applied to the electrodes 12a to 12d. Then, the vibration member 10 vibrates in the front-rear direction as indicated by the white arrow in FIG. 2 due to the change in the film thickness of the dielectric films 11a to 11c. Thereby, air vibrates and a sound is generated.

[Function and effect]
Next, the effect of the polymer speaker of this embodiment is demonstrated. In the polymer speaker 1 of the present embodiment, the front foam layer 20a and the back foam layer 20b are disposed on the front and rear surfaces of the vibration member 10. Deformation in the surface direction of the vibration member 10 is regulated by the front-side foam layer 20a and the back-side foam layer 20b. And the rigidity in the surface direction of the vibration member 10 becomes large. Therefore, it is difficult for wrinkles to occur in the dielectric films 11a to 11c when a bias voltage is applied. Thereby, division vibration can be suppressed. As a result, the polymer speaker 1 can generate sound in a wide frequency range.

  The front side foam layer 20a and the back side foam layer 20b are made of polyurethane foam. Polyurethane foam is flexible. For this reason, the front-back foam layer 20a and the back-side foam layer 20b are unlikely to hinder the movement of the vibration member 10 in the front-rear direction. The polyurethane foam is an open cell body with an air flow rate of 1200 ml / min. That is, the bubbles of the polyurethane foam are sufficiently communicated. For this reason, the gas in the polyurethane foam tends to escape. Therefore, the front-side foam layer 20a and the back-side foam layer 20b are unlikely to become air springs, and the movement of the vibration member 10 in the front-rear direction is hardly hindered. Therefore, in the polymer speaker 1, the speaker performance is unlikely to deteriorate.

  The vibration member 10 includes dielectric films 11a to 11c made of elastomer and electrodes 12a to 12d printed on the surface thereof. For this reason, the polymer speaker 1 is thinner and lighter than a conventional dynamic speaker unit having a permanent magnet or a voice coil. Moreover, it can be manufactured at a relatively low cost. Furthermore, the polymer speaker 1 does not require an enclosure. Therefore, the polymer speaker 1 is lightweight, easy to miniaturize, and relatively inexpensive.

  The dielectric films 11a to 11c are made of H-NBR. For this reason, the dielectric films 11a to 11c are flexible and excellent in stretchability. The electrodes 12a to 12d are made of a flexible conductive material in which silicone powder is filled with silicone powder. For this reason, the electrodes 12a to 12d are also flexible and can expand and contract integrally with the dielectric films 11a to 11c. That is, the electrodes 12a to 12d are unlikely to hinder the movement of the dielectric films 11a to 11c. Therefore, the vibration member 10 is likely to vibrate even with an applied voltage in a low frequency region. As a result, the polymer speaker 1 can also generate sound in a low frequency region. Further, even if the vibration is repeated, the electrodes 12a to 12d are hardly peeled off from the dielectric films 11a to 11c. Therefore, the vibration member 10 is excellent in durability.

  The vibrating member 10 is composed of a plurality of dielectric films 11a to 11c stacked via electrodes 12a to 12d. Therefore, as compared with a configuration in which electrodes are arranged on both surfaces of one dielectric film, the deformation amount of the vibrating member 10 with respect to the applied voltage is increased, and the output sound pressure is increased.

[Others]
The embodiment of the polymer speaker of the present invention has been described above. However, the embodiment of the polymer speaker of the present invention is not limited to the above embodiment. Various modifications and improvements that can be made by those skilled in the art are also possible.

  For example, in the above embodiment, a dielectric film made of H-NBR is used. However, the material of the dielectric film is not particularly limited as long as it is an elastomer or a resin. For example, it is desirable to use an elastomer having a high relative dielectric constant. Specifically, an elastomer having a relative dielectric constant (100 Hz) at room temperature of 2 or more, further 5 or more is desirable. For example, an elastomer having a polar functional group such as an ester group, a carboxyl group, a hydroxyl group, a halogen group, an amide group, a sulfone group, a urethane group, or a nitrile group, or an elastomer added with a polar low molecular weight compound having these polar functional groups Should be adopted. Suitable elastomers other than H-NBR include silicone rubber, acrylonitrile-butadiene rubber (NBR), ethylene-propylene-diene rubber (EPDM), acrylic rubber, urethane rubber, epichlorohydrin rubber, chlorosulfonated polyethylene, and chlorinated polyethylene. Etc. Suitable resins include polyethylene, polypropylene, polyurethane, polystyrene (including cross-linked expanded polystyrene), polyvinyl chloride, vinylidene chloride copolymer, ethylene-vinyl acetate copolymer, and the like.

  In the above embodiment, the electrode is formed from a flexible conductive material. However, the material of the electrode is not particularly limited. For example, you may form from a metal and a carbon material. From the viewpoint of imparting stretchability, for example, an electrode can be formed by knitting metal or the like into a mesh shape. Moreover, you may form from electroconductive polymers, such as polyethylenedioxythiophene (PEDOT). When a flexible conductive material including a binder and a conductive material is employed, it is desirable to use an elastomer for the binder. Suitable examples of the elastomer include silicone rubber, NBR, EPDM, natural rubber, styrene-butadiene rubber (SBR), acrylic rubber, urethane rubber, epichlorohydrin rubber, chlorosulfonated polyethylene, and chlorinated polyethylene. In addition, as the conductive material, carbon materials such as carbon black, carbon nanotube, and graphite, metal materials such as silver, gold, copper, nickel, rhodium, palladium, chromium, titanium, platinum, iron, and alloys thereof, indium oxide What is necessary is just to select suitably from electroconductive oxides, such as what doped other metals, such as tin (ITO), titanium oxide, and zinc oxide, aluminum, antimony. A conductive material may be used individually by 1 type, and 2 or more types may be mixed and used for it.

  In the above embodiment, the vibration member is configured by laminating three layers of dielectric films via the electrodes. However, the number of dielectric films constituting the vibration member is not particularly limited. For example, electrodes may be arranged on both surfaces of one dielectric film. Further, the dielectric film may be fixed to the frame while being stretched in the plane direction. The size and shape of the electrodes are not particularly limited as long as a voltage can be applied to the dielectric film. For example, you may arrange | position so that the whole surface of a dielectric film may be covered.

  The material of the frame is not particularly limited as long as it can support the vibration member and has an insulating property. The shape of the frame may be an elliptical frame shape or a rectangular frame shape.

  The material of the foam layer is not particularly limited. In addition to urethane foam, foamed polyethylene and the like can be mentioned. Moreover, in order to make the foam layer into an open cell body, it is desirable to adjust the raw material composition. Alternatively, it is desirable to perform communication processing such as air crushing after foam molding. Moreover, you may adjust the communication form of a bubble, such as making a bubble communicate in a thickness direction.

  In the said embodiment, the front side foam layer and back side foam layer which were shape | molded previously were affixed on the front and back both surfaces of the vibration member. However, the front-side foam layer and the back-side foam layer and the vibration member may be integrally formed. In this case, the foamed resin raw material may be injected and foam-molded in a state where the vibration member is disposed in the cavity of the mold.

  The polymer speaker of the present invention can be used as, for example, an automobile headrest speaker, seat speaker, ceiling speaker, floor speaker, instrument panel speaker, door speaker and the like. Of course, you may arrange | position other than a vehicle. Moreover, the polymer speaker of the present invention may be used not only to reproduce sound but also as an active noise canceller.

1: Polymer speaker 10: Vibration member 11a-11c: Dielectric film 12a-12d: Electrode 120a-120d: Terminal part 20a: Front side foam layer 20b: Back side foam layer 30a: Front side frame 30b: Back side frame 31: Bolt 32 :nut

Claims (7)

A vibration member comprising a dielectric film made of an elastomer or a resin, and a plurality of electrodes disposed via the dielectric film;
A foam layer disposed on both front and back surfaces of the vibration member;
A frame that supports a peripheral portion of the vibration member;
Equipped with a,
The foam layer is adhered to the vibration member with an adhesive, or is integrally formed with the vibration member,
The frame includes a front frame disposed on the front surface side of the vibration member and a back frame disposed on the back surface side of the vibration member. The front frame and the back frame are front and back surfaces of the vibration member. A polymer speaker characterized in that the vibration member is arranged so as to face each other without covering a directional side surface, and a peripheral portion of the vibration member is sandwiched between the front frame and the back frame . The polymer speaker according to claim 1, wherein the dielectric film is made of hydrogenated nitrile rubber . The polymer speaker according to claim 1, wherein the foam layer is an open cell body. The polymer speaker according to claim 3 , wherein the air flow rate of the foam layer is 1000 ml / min or more. The polymer speaker according to any one of claims 1 to 4 , wherein the foam layer is made of urethane foam.   The polymer speaker according to claim 1, wherein the electrode is made of a flexible conductive material including an elastomer and a conductive material.   The polymer speaker according to claim 1, wherein the vibration member includes a plurality of the dielectric films, and the dielectric films and the electrodes are alternately stacked.

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