WO2017030192A1 - Film de conversion électro-acoustique - Google Patents

Film de conversion électro-acoustique Download PDF

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Publication number
WO2017030192A1
WO2017030192A1 PCT/JP2016/074258 JP2016074258W WO2017030192A1 WO 2017030192 A1 WO2017030192 A1 WO 2017030192A1 JP 2016074258 W JP2016074258 W JP 2016074258W WO 2017030192 A1 WO2017030192 A1 WO 2017030192A1
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Prior art keywords
conversion film
polymer material
piezoelectric
electrode
viscoelastic
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PCT/JP2016/074258
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English (en)
Japanese (ja)
Inventor
井上　大輔
信 小澤
三好　哲
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富士フイルム株式会社
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Priority to JP2017535576A priority Critical patent/JP6505845B2/ja
Publication of WO2017030192A1 publication Critical patent/WO2017030192A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R17/00—Piezoelectric transducers; Electrostrictive transducers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/20—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/30—Piezoelectric or electrostrictive devices with mechanical input and electrical output, e.g. functioning as generators or sensors

Definitions

  • the present invention relates to an electroacoustic conversion film used for an acoustic device such as a speaker.
  • the speakers used in these thin displays are also required to be lighter and thinner.
  • the speaker used for this is also required to be flexible.
  • the shape of a conventional speaker is generally a funnel-shaped so-called cone type or a spherical dome shape.
  • the speaker cannot be sufficiently thinned, and the lightness and flexibility may be impaired.
  • carrying and the like are troublesome.
  • An electroacoustic conversion film disclosed in Patent Document 1 includes a polymer composite piezoelectric material (piezoelectric layer) in which piezoelectric particles are dispersed in a viscoelastic matrix made of a polymer material having viscoelasticity at room temperature, It has a thin film electrode formed on both surfaces of the molecular composite piezoelectric material and a protective layer formed on the surface of the thin film electrode.
  • the object of the present invention is to solve such problems of the prior art, and it is possible to improve the sound pressure level by increasing the conversion efficiency between electricity and sound, and in the frequency characteristics, the peak and dip of the sound pressure level are improved.
  • An object of the present invention is to provide an electroacoustic conversion film that has less unevenness and can have a wider band.
  • a polymer composite piezoelectric material obtained by dispersing piezoelectric particles in a viscoelastic matrix having a polymer material having a cyanoethyl group exhibiting viscoelasticity at room temperature. And two thin film electrodes laminated on both surfaces of the polymer composite piezoelectric material, and two protective layers laminated on the two thin film electrodes, respectively, and the viscoelastic matrix has a relative dielectric constant of 10 or more
  • the present inventors have found that the above-mentioned problems can be solved by containing an additive polymer material that is a polymer material of the present invention, and completed the present invention. That is, this invention provides the electroacoustic conversion film of the following structures.
  • a polymer composite piezoelectric material obtained by dispersing piezoelectric particles in a viscoelastic matrix containing a polymer material having a cyanoethyl group exhibiting viscoelasticity at room temperature; Two thin film electrodes laminated on both sides of a polymer composite piezoelectric material; Two protective layers stacked on each of the two thin-film electrodes,
  • the viscoelastic matrix is an electroacoustic conversion film containing an additive polymer material which is a polymer material having a relative dielectric constant of 10 or more.
  • the electroacoustic conversion film can improve the sound pressure level by increasing the conversion efficiency between electricity and sound, and can reduce the peak in the sound pressure level and the unevenness of the dip in the frequency characteristics, thereby increasing the bandwidth. Can be provided.
  • FIG. 1 It is sectional drawing which shows an example of the electroacoustic conversion film of this invention notionally. It is a conceptual diagram for demonstrating an example of the preparation methods of an electroacoustic conversion film. It is a conceptual diagram for demonstrating an example of the preparation methods of an electroacoustic conversion film. It is a conceptual diagram for demonstrating an example of the preparation methods of an electroacoustic conversion film. It is a conceptual diagram for demonstrating an example of the preparation methods of an electroacoustic conversion film. It is a conceptual diagram for demonstrating an example of the preparation methods of an electroacoustic conversion film. It is a top view which represents typically an example of the electroacoustic transducer using the electroacoustic conversion film of this invention. FIG.
  • 3B is a sectional view taken along line BB in FIG. 3A. It is sectional drawing for demonstrating another example of an electroacoustic transducer. It is sectional drawing for demonstrating another example of an electroacoustic transducer. It is sectional drawing for demonstrating another example of an electroacoustic transducer. It is sectional drawing which shows another example of an electroacoustic transducer.
  • FIG. 1 sectional drawing which represents typically an example of the electroacoustic conversion film of this invention is shown.
  • Such an electroacoustic conversion film is used as a diaphragm of an electroacoustic transducer, as will be described later.
  • the electroacoustic conversion film expands in the in-plane direction by applying a voltage to the electroacoustic conversion film, the electroacoustic conversion film absorbs the extension, and the electroacoustic conversion film moves upward (radiation direction of sound).
  • the electroacoustic conversion film contracts in the in-plane direction by applying a voltage to the electroacoustic conversion film
  • the electroacoustic conversion film is moved downward (case side) to absorb this contraction.
  • the electroacoustic transducer converts vibration (sound) and an electric signal by vibration caused by repeated expansion and contraction of the electroacoustic conversion film.
  • Such electroacoustic transducers are used as various acoustic devices such as full-range speakers, tweeters, squawkers, woofers, speakers, headphones, earphone speakers, noise cancellers, microphones, and pickups used in musical instruments such as guitars. It is used to input an electric signal to the electroacoustic conversion film and reproduce the sound by vibration according to the electric signal, or to convert the vibration of the electroacoustic conversion film by receiving the sound wave into an electric signal. It is what is done.
  • An electroacoustic conversion film (hereinafter also referred to as “conversion film”) 10 shown in FIG. 1 includes a piezoelectric layer 12 that is a sheet having piezoelectricity, a lower thin film electrode 14 provided on one surface of the piezoelectric layer 12, and The upper thin film electrode 16 provided on the other surface, the lower protective layer 18 provided on the surface of the lower thin film electrode 14, and the upper protective layer 20 provided on the surface of the upper thin film electrode 16 are configured.
  • the piezoelectric layer 12 is made of a polymer composite piezoelectric material.
  • the polymer composite piezoelectric material forming the piezoelectric layer 12 is obtained by dispersing piezoelectric particles 26 in a viscoelastic matrix 24 containing a polymer material having a cyanoethyl group. is there.
  • the viscoelastic matrix 24 constituting the polymer composite piezoelectric material contains an additive polymer material that is a polymer material having a relative dielectric constant of 10 or more.
  • the electroacoustic conversion film of the present invention can increase the conversion efficiency between electricity and sound and improve the sound pressure level.
  • the frequency characteristic has a peak in the sound pressure level, It is possible to increase the bandwidth by reducing the unevenness of the dip. This point will be described in detail later.
  • the piezoelectric layer 12 is polarized.
  • the conversion film 10 is suitably used for a flexible speaker such as a speaker for a flexible display.
  • the polymer composite piezoelectric body (piezoelectric layer 12) used for the flexible speaker preferably has the following requirements.
  • (I) Flexibility For example, when gripping in a loosely bent state like a newspaper or a magazine for portable use, it is constantly subject to a relatively slow and large bending deformation of several Hz or less from the outside. become. At this time, if the polymer composite piezoelectric material is hard, a large bending stress is generated, and a crack is generated at the interface between the polymer matrix and the piezoelectric particles, which may eventually lead to destruction. Accordingly, the polymer composite piezoelectric body is required to have an appropriate softness.
  • the loss tangent of the polymer composite piezoelectric material is appropriately large.
  • (Ii) Sound quality The speaker vibrates the piezoelectric particles at an audio band frequency of 20 Hz to 20 kHz, and the vibration plate (polymer composite piezoelectric material) vibrates as a whole by the vibration energy, so that sound is reproduced.
  • the polymer composite piezoelectric body is required to have an appropriate hardness.
  • the frequency characteristic of the speaker is smooth, the amount of change in the sound quality when the lowest resonance frequency f 0 with the change in the curvature is changed becomes small. Therefore, the loss tangent of the polymer composite piezoelectric material is required to be moderately large.
  • the polymer composite piezoelectric material used for a flexible speaker is required to be hard for vibrations of 20 Hz to 20 kHz and soft for vibrations of several Hz or less.
  • the loss tangent of the polymer composite piezoelectric body is required to be reasonably large with respect to vibrations of all frequencies of 20 kHz or less.
  • polymer solids have a viscoelastic relaxation mechanism, and as the temperature increases or the frequency decreases, large-scale molecular motion decreases (relaxes) the storage elastic modulus (Young's modulus) or maximizes the loss elastic modulus (absorption). As observed. Among them, the relaxation caused by the micro Brownian motion of the molecular chain in the amorphous region is called main dispersion, and a very large relaxation phenomenon is observed. The temperature at which this main dispersion occurs is the glass transition point (Tg), and the viscoelastic relaxation mechanism appears most remarkably.
  • Tg glass transition point
  • a polymer material having a glass transition point at room temperature in other words, a polymer material having viscoelasticity at room temperature is used as a matrix, so that vibrations of 20 Hz to 20 kHz can be prevented.
  • a polymer composite piezoelectric material that is hard and softly behaves with respect to slow vibrations of several Hz or less is realized.
  • a polymer material having a glass transition temperature at a frequency of 1 Hz at room temperature that is, 0 to 50 ° C.
  • “normal temperature” refers to a temperature range of about 0 to 50 ° C.
  • a material having a cyanoethyl group can be used as the polymer material having viscoelasticity at room temperature.
  • a polymer material having a maximum value of loss tangent Tan ⁇ at a frequency of 1 Hz in a dynamic viscoelasticity test at room temperature, that is, 0 to 50 ° C. is 0.5 or more.
  • the polymer material preferably has a storage elastic modulus (E ′) at a frequency of 1 Hz as measured by dynamic viscoelasticity of 100 MPa or more at 0 ° C. and 10 MPa or less at 50 ° C.
  • E ′ storage elastic modulus
  • the polymer material has a relative dielectric constant of 10 or more at 25 ° C.
  • the polymer material preferably has a relative dielectric constant of 10 or less at 25 ° C.
  • cyanoethylated polyvinyl alcohol (cyanoethylated PVA) is preferably exemplified.
  • vinylidene cyanide-vinyl acetate copolymer cyanoethyl cellulose, cyanoethyl hydroxy saccharose, cyanoethyl hydroxy cellulose, cyanoethyl hydroxy pullulan, cyanoethyl methacrylate, cyanoethyl acrylate, cyanoethyl hydroxyethyl cellulose, cyanoethyl amylose, cyanoethyl hydroxypropyl cellulose, Cyano groups such as cyanoethyl dihydroxypropyl cellulose, cyanoethyl hydroxypropyl amylose, cyanoethyl polyacrylamide, cyanoethyl polyacrylate, cyanoethyl pullulan, cyanoethyl
  • the polymeric material can be mentioned having a cyanoethyl group of synthetic rubbers such as nitrile rubber or chloroprene rubber. Of these, cyanoethylated PVA is preferably used. In addition, these polymeric materials may use only 1 type, and may use multiple types together (mixed).
  • the viscoelastic matrix 24 using such a polymer material having a cyanoethyl group may be used in combination with another polymer material having viscoelasticity at room temperature, if necessary.
  • examples of other polymer materials having viscoelasticity at room temperature include polyvinyl acetate, polyvinylidene chloride co-acrylonitrile, polystyrene-vinyl polyisoprene block copolymer, polyvinyl methyl ketone, and polybutyl methacrylate.
  • commercially available products such as Hibler 5127 (manufactured by Kuraray Co., Ltd.) can be suitably used.
  • a polymer material having a relative dielectric constant of 10 or more at 25 ° C. (hereinafter referred to as “added polymer material”) is applied to the viscoelastic matrix 24 mainly composed of such a polymer material having a cyanoethyl group. Is also added).
  • the applicant of the present application dispersed piezoelectric particles in a viscoelastic matrix made of a polymer material having viscoelasticity at room temperature as a thin piezoelectric film capable of stably reproducing high-quality sound.
  • An electroacoustic conversion film having a polymer composite piezoelectric body (piezoelectric layer) thus formed, a thin film electrode formed on both surfaces of the piezoelectric layer, and a protective layer formed on the surface of the thin film electrode has been proposed.
  • the electroacoustic conversion film using such a polymer composite piezoelectric material obtained by dispersing piezoelectric particles in a viscoelastic matrix made of a polymer material having viscoelasticity at room temperature as a piezoelectric layer Furthermore, investigations were carried out to improve the conversion efficiency, and to reduce the peak and dip irregularities in the sound pressure level in the frequency characteristics to widen the band.
  • an additive polymer material having a relative dielectric constant of 10 or more is added to the viscoelastic matrix 24 mainly composed of a polymer material having a cyanoethyl group exhibiting viscoelasticity at room temperature,
  • the dielectric constant of the viscoelastic matrix 24 is a maximum value of the sound pressure level in a graph representing the relationship between the frequency and the sound pressure level, and the dip is a minimum value adjacent to the maximum value. That is, the smaller the difference between the sound pressure level peak and the dip, the smoother the frequency characteristics and the wider the band.
  • the relative dielectric constant at 25 ° C. of the additive polymer material is preferably 15 or more, and more preferably 18 or more.
  • cyanoethyl pullulan As the additive polymer material having a relative dielectric constant of 10 or more, cyanoethyl pullulan, cyanoethyl cellulose, nitrile rubber, cyanoethyl hydroxycellulose, cyanoethyl hydroxyethyl cellulose, cyanoethyl amylose, cyanoethyl hydroxypropyl cellulose, cyanoethyl dihydroxypropyl cellulose, cyanoethyl polyhydroxymethylene, cyanoethyl Examples thereof include glycidol pullulan and cyanoethyl sorbidol.
  • the additive polymer material it is preferable to use a polymer material having a loss tangent of 0.05 or less at 25 ° C. and 20 Hz.
  • the smaller the loss tangent the greater the mechanical quality factor (Q value), which is an index of the sharpness of resonance characteristics (resonance strength), that is, the resonance becomes sharper.
  • Q value mechanical quality factor
  • resonance becomes sharp in a high frequency band (1 kHz or more). It has been found that sound pressure is improved by utilizing this resonance.
  • the frequency characteristics which are one of the indicators of acoustic performance, cause unevenness in the sound pressure level, and peaks and dips become obvious and become narrower. It has been found that, by adding, smooth frequency characteristics can be obtained without making peaks and dip appear, and a broad band can be obtained.
  • Examples of the additive polymer material having a loss tangent of 0.05 or less at 25 ° C. and 20 Hz include cyanoethyl pullulan and cyanoethyl cellulose.
  • the additive polymer material it is preferable to use a polymer material having a volume resistance of 1 ⁇ 10 12 ⁇ ⁇ cm or more.
  • a polymer material having a volume resistance of 1 ⁇ 10 12 ⁇ ⁇ cm or more as the additive polymer material, the withstand voltage of the piezoelectric layer 12 can be increased, and the electrode pair holding the piezoelectric layer 12 is sandwiched. Even when a high voltage is applied to (lower thin film electrode 14 and upper thin film electrode 16), dielectric breakdown of the piezoelectric layer 12 is less likely to occur, and sound can be reproduced appropriately.
  • the piezoelectric layer 12 can be formed thinner, reducing the deflection due to its own weight, and by reducing the weight, the followability of the piezoelectric film with respect to the applied voltage is improved, and the sound is reduced. Pressure and sound quality can be improved. Moreover, flexibility can be imparted.
  • Examples of the additive polymer material having a volume resistance of 1 ⁇ 10 12 ⁇ ⁇ cm or more include cyanoethyl pullulan.
  • the amount of the added polymer material is not limited, but is preferably 60% by mass or less, more preferably 10% by mass or more and 30% by mass or less, as a proportion of the viscoelastic matrix 24. .
  • the ratio of the additive polymer material it is possible to improve the sound pressure, increase the bandwidth, and improve the withstand voltage.
  • the viscoelastic matrix 24 is a polymer material (viscoelastic material) that exhibits viscoelasticity at room temperature and has a cyanoethyl group for the purpose of adjusting dielectric properties and mechanical properties, etc., and a high dielectric constant of 10 or more. In addition to molecular materials, other polymer materials may be added as necessary.
  • polymer material that can be added examples include polyvinylidene fluoride, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, polyvinylidene fluoride-trifluoroethylene copolymer, and polyfluoride.
  • fluorine-based polymers such as vinylidene fluoride-tetrafluoroethylene copolymer
  • synthetic rubbers such as chloroprene rubber.
  • the polymer material added in addition to the material having viscoelasticity at room temperature is not limited to one type, and a plurality of types may be added. Also good.
  • thermoplastic resins such as vinyl chloride resin, polyethylene, polystyrene, methacrylic resin, polybutene, isobutylene, phenol resin, urea resin, melamine resin, alkyd resin, mica, etc.
  • a thermosetting resin may be added.
  • a tackifier such as rosin ester, rosin, terpene, terpene phenol, petroleum resin, etc. may be added.
  • the addition amount when adding a viscoelastic material such as cyanoethylated PVA and a polymer material other than an additive polymer material having a relative dielectric constant of 10 or more is particularly limited. However, it is preferably 30% by mass or less as a percentage of the viscoelastic matrix 24.
  • the polymer material means a material having a molecular weight of 10,000 or more.
  • dielectric particles may be added to the viscoelastic matrix 24 for the purpose of increasing the dielectric constant of the piezoelectric layer 12.
  • the dielectric particles are particles having a high relative dielectric constant of 80 or more at 25 ° C.
  • the dielectric particles include lead zirconate titanate (PZT), barium titanate (BaTiO 3 ), titanium oxide (TiO 2 ), strontium titanate (SrTiO 3 ), and lead lanthanum zirconate titanate (PLZT).
  • PZT lead zirconate titanate
  • BaTiO 3 barium titanate
  • TiO 2 titanium oxide
  • strontium titanate SrTiO 3
  • lead lanthanum zirconate titanate PZT
  • Examples thereof include zinc oxide (ZnO), solid solution (BFBT) of barium titanate and bismuth ferrite (BiFeO 3 ), and the like.
  • barium titanate (BaTiO 3 ) as the dielectric particles in terms
  • the dielectric particles preferably have an average particle size of 0.5 ⁇ m or less. Further, the volume fraction of the dielectric particles with respect to the total volume of the viscoelastic matrix and the dielectric particles is preferably 5 to 45%, more preferably 10 to 30%, and particularly preferably 20 to 30%.
  • the piezoelectric particles 26 are made of ceramic particles having a perovskite type or wurtzite type crystal structure.
  • ceramic particles constituting the piezoelectric particles 26 for example, lead zirconate titanate (PZT), lead lanthanum zirconate titanate (PLZT), barium titanate (BaTiO 3 ), zinc oxide (ZnO), and Examples thereof include a solid solution (BFBT) of barium titanate and bismuth ferrite (BiFe 3 ).
  • PZT lead zirconate titanate
  • PLAZT lead lanthanum zirconate titanate
  • BaTiO 3 barium titanate
  • ZnO zinc oxide
  • BFBT solid solution
  • these ceramic particles may use only 1 type, and may use multiple types together.
  • the particle size of the piezoelectric particles 26 may be appropriately selected according to the size and application of the conversion film 10, but is preferably 1 to 10 ⁇ m according to the study of the present inventors. By setting the particle diameter of the piezoelectric particles 26 within the above range, favorable results can be obtained in terms of achieving both high piezoelectric characteristics and flexibility and improving withstand voltage.
  • the piezoelectric particles 26 in the piezoelectric layer 12 are uniformly and regularly dispersed in the viscoelastic matrix 24, but the present invention is not limited to this. That is, the piezoelectric particles 26 in the piezoelectric layer 12 may be irregularly dispersed in the viscoelastic matrix 24 as long as it is preferably dispersed uniformly.
  • the quantity ratio between the viscoelastic matrix 24 and the piezoelectric particles 26 in the piezoelectric layer 12 is required for the size and thickness of the conversion film 10 in the surface direction, the use of the conversion film 10, and the conversion film 10. What is necessary is just to set suitably according to the characteristic etc. to be.
  • the volume fraction of the piezoelectric particles 26 in the piezoelectric layer 12 is preferably 30 to 70%, particularly preferably 50% or more. 70% is more preferable.
  • the thickness of the piezoelectric layer 12 is not particularly limited, and is appropriately set according to the size of the conversion film 10, the use of the conversion film 10, the characteristics required for the conversion film 10, and the like. do it.
  • the thickness of the piezoelectric layer 12 is reduced, and by reducing the thickness, the followability of the piezoelectric film with respect to the applied voltage is improved. Sound pressure and sound quality can be improved. Moreover, flexibility can be imparted.
  • the thickness of the piezoelectric layer 12 is too thin, a local short circuit may occur when a voltage is applied with a continuous rigidity or when a high voltage is applied.
  • the thickness of the piezoelectric layer 12 is preferably 5 ⁇ m to 100 ⁇ m, more preferably 8 ⁇ m to 50 ⁇ m, particularly preferably 10 to 40 ⁇ m, and particularly preferably 15 to 25 ⁇ m.
  • the piezoelectric layer 12 is preferably polarized (polled) as described above. The polarization process will be described in detail later.
  • the conversion film 10 of the present invention has a lower thin film electrode 14 formed on one surface of the piezoelectric layer 12 and a lower protective layer 18 formed on the lower thin film electrode 12.
  • the upper thin film electrode 16 is formed on the other surface, and the upper protective layer 20 is formed thereon.
  • the upper thin film electrode 16 and the lower thin film electrode 14 form an electrode pair.
  • the conversion film 10 covers, for example, the upper thin-film electrode 16 and an electrode lead-out portion that pulls out the electrode from the lower thin-film electrode 14 and a region where the piezoelectric layer 12 is exposed.
  • an insulating layer for preventing a short circuit or the like may be provided.
  • the thin-film electrode and the protective layer may be provided with a protruding portion outside the surface of the piezoelectric layer, or a part of the protective layer is removed to form a hole. Then, a conductive material such as a silver paste may be inserted into the hole portion to electrically connect the conductive material and the thin film electrode to form an electrode lead-out portion.
  • the number of electrode lead portions is not limited to one, and may include two or more electrode lead portions. In particular, in the case of a configuration in which a part of the protective layer is removed and a conductive material is inserted into the hole portion to form an electrode lead portion, it is necessary to have three or more electrode lead portions in order to ensure energization more reliably. preferable.
  • the conversion film 10 has both sides of the piezoelectric layer 12 sandwiched between electrode pairs, that is, the upper thin film electrode 16 and the lower thin film electrode 14, and the laminate is sandwiched between the upper protective layer 20 and the lower protective layer 18. It has the composition which becomes. Thus, the region held by the upper thin film electrode 16 and the lower thin film electrode 14 is driven according to the applied voltage.
  • the upper protective layer 20 and the lower protective layer 18 cover the upper thin film electrode 16 and the lower thin film electrode 14, and play a role of imparting appropriate rigidity and mechanical strength to the piezoelectric layer 12. . That is, in the conversion film 10 of the present invention, the piezoelectric layer 12 composed of the viscoelastic matrix 24 and the piezoelectric particles 26 exhibits very excellent flexibility against slow bending deformation, Depending on the application, rigidity and mechanical strength may be insufficient.
  • the conversion film 10 is provided with an upper protective layer 20 and a lower protective layer 18 to supplement it. Note that the lower protective layer 18 and the upper protective layer 20 are different in arrangement position and have the same configuration. Therefore, in the following description, it is not necessary to distinguish the lower protective layer 18 and the upper protective layer 20 from each other. Are collectively referred to as a protective layer.
  • the upper protective layer 20 and the lower protective layer 18 are not particularly limited, and various sheet materials can be used.
  • various resin films are preferably exemplified.
  • PET polyethylene terephthalate
  • PP polypropylene
  • PS polystyrene
  • PC polycarbonate
  • PPS polyphenylene sulfite
  • PMMA polymethyl methacrylate
  • PEI Polyetherimide
  • PEI polyimide
  • PA polyamide
  • PEN polyethylene naphthalate
  • TAC triacetylcellulose
  • cyclic olefin resin are preferably used.
  • polyamide, polyimide, polyetherimide, polycarbonate, and triacetyl cellulose are preferably used from the viewpoint of exhibiting excellent heat resistance at a glass transition temperature Tg of 150 ° C. or higher. From these, appearance damage due to heat generation at the time of voltage application can be prevented, and a standing test and a driving test at a high temperature can be endured.
  • the thickness of the upper protective layer 20 and the lower protective layer 18 is not particularly limited.
  • the thicknesses of the upper protective layer 20 and the lower protective layer 18 are basically the same, but may be different.
  • the rigidity of the upper protective layer 20 and the lower protective layer 18 is too high, not only the expansion and contraction of the piezoelectric layer 12 is restricted, but also the flexibility is impaired, so that the mechanical strength and the sheet-like material are good.
  • the upper protective layer 20 and the lower protective layer 18 are more advantageous as they are thinner.
  • the thickness of the upper protective layer 20 and the lower protective layer 18 is not more than twice the thickness of the piezoelectric layer 12, it is possible to ensure both rigidity and appropriate flexibility. In this respect, preferable results can be obtained.
  • the thickness of the piezoelectric layer 12 is 20 ⁇ m and the upper protective layer 20 and the lower protective layer 18 are made of PET
  • the thickness of the upper protective layer 20 and the lower protective layer 18 is preferably 40 ⁇ m or less, more preferably 20 ⁇ m or less. In particular, the thickness is preferably 15 ⁇ m or less.
  • an upper thin film electrode (hereinafter also referred to as an upper electrode) 16 is provided between the piezoelectric layer 12 and the upper protective layer 20, and a lower thin film electrode is provided between the piezoelectric layer 12 and the lower protective layer 18. (Hereinafter also referred to as a lower electrode) 14 are formed.
  • the upper electrode 16 and the lower electrode 14 are provided for applying an electric field to the conversion film 10 (piezoelectric layer 12).
  • the lower electrode 14 and the upper electrode 16 are different in size and arrangement position, and have the same configuration. Therefore, in the following description, it is not necessary to distinguish the lower electrode 14 and the upper electrode 16 from each other. These members are collectively referred to as a thin film electrode.
  • the material for forming the upper electrode 16 and the lower electrode 14 is not particularly limited, and various conductors can be used. Specific examples include carbon, palladium, iron, tin, aluminum, nickel, platinum, gold, silver, copper, chromium and molybdenum, alloys thereof, indium tin oxide, and the like. Among them, any of copper, aluminum, gold, silver, platinum, and indium tin oxide is preferably exemplified.
  • the method for forming the upper electrode 16 and the lower electrode 14 is not particularly limited, and a vapor deposition method (vacuum film forming method) such as vacuum vapor deposition or sputtering, film formation by plating, or a foil formed of the above materials. Various known methods such as a method of sticking can be used.
  • a thin film of copper or aluminum formed by vacuum vapor deposition is preferably used as the upper electrode 16 and the lower electrode 14 because, for example, the flexibility of the conversion film 10 can be ensured.
  • a copper thin film formed by vacuum deposition is particularly preferably used.
  • the thicknesses of the upper electrode 16 and the lower electrode 14 are not particularly limited. The thicknesses of the upper electrode 16 and the lower electrode 14 are basically the same, but may be different.
  • the upper electrode 16 and the lower electrode 14 are more advantageous as they are thinner as long as the electric resistance is not excessively high.
  • the product of the thickness of the upper electrode 16 and the lower electrode 14 and the Young's modulus is less than the product of the thickness of the upper protective layer 20 and the lower protective layer 18 and the Young's modulus, This is preferable because flexibility is not greatly impaired.
  • the upper protective layer 20 and the lower protective layer 18 are PET (Young's modulus: about 6.2 GPa) and the upper electrode 16 and the lower electrode 14 are made of copper (Young's modulus: about 130 GPa)
  • the upper protective layer 20 Assuming that the thickness of the lower protective layer 18 is 25 ⁇ m, the thickness of the upper electrode 16 and the lower electrode 14 is preferably 1.2 ⁇ m or less, more preferably 0.3 ⁇ m or less, and particularly preferably 0.1 ⁇ m or less.
  • the thin film electrode is not necessarily formed corresponding to the entire surface of the piezoelectric layer 12 (the lower protective layer 18 and / or the upper protective layer 20). That is, at least one of the thin film electrodes may be smaller than the piezoelectric layer 12, for example, and the piezoelectric layer 12 and the protective layer may be in direct contact with each other at the periphery of the conversion film 10.
  • the protective layer having the thin film electrode formed on the entire surface does not need to be formed on the entire surface of the piezoelectric layer 12.
  • the second protective layer that is in direct contact with the piezoelectric layer 12 may be separately provided on the surface side of the protective layer.
  • a coating layer may be further provided between the thin film electrode and the piezoelectric layer 12 for the purpose of improving adhesion and flexibility.
  • the coating layer may be coated on the thin film electrode or on the piezoelectric layer 12.
  • a thermoplastic resin such as poly (meth) acryl, polyurethane, polyester polyolefin, PVA, or polystyrene, or a thermosetting resin such as phenol resin or melamine resin can be used as the polymer component.
  • a dielectric polymer is preferably used in order to improve acoustic performance.
  • the above-described polymers can be preferably used.
  • high dielectric particles, an antistatic agent, a surfactant, a thickener, a crosslinking agent, and the like may be added.
  • the layer structure of the conversion film 10 includes a piezoelectric layer 12, a lower thin film electrode 14 stacked on one surface of the piezoelectric layer 12, and a lower protective layer stacked on the lower thin film electrode 14. 18, the upper thin film electrode 16 laminated on the other surface of the piezoelectric layer 12, and the upper protective layer 20 laminated on the upper thin film electrode 16, but is not limited thereto.
  • an area where the piezoelectric layer 12 is exposed may be covered with an insulating layer for preventing a short circuit, a colored layer for covering the thin film electrode, and the like.
  • the layer configuration includes a piezoelectric layer 12, a lower thin film electrode 14 stacked on one surface of the piezoelectric layer 12, a lower colored layer stacked on the lower thin film electrode 14, A lower protective layer 18 laminated on the lower colored layer, an upper thin film electrode 16 laminated on the other surface of the piezoelectric layer 12, an upper colored layer laminated on the upper thin film electrode 16, and an upper colored layer
  • the upper protective layer 20 may be configured to be laminated.
  • the transmission density of the colored layer is preferably 0.3 or more, and more preferably 0.5 or more.
  • the transmission density is an optical density measured as a ratio of the transmitted light to the incident light.
  • the transmittance when the transmission density is 0.3 is about 50%, and the transmittance when the transmission density is 0.5. Is about 30%.
  • the thickness of the colored layer is preferably 1 ⁇ m or less, more preferably 100 nm or less, and particularly preferably 40 nm or less.
  • the colored layer preferably has a low electrical resistivity, and is preferably 1 ⁇ 10 ⁇ 7 ⁇ m or less.
  • the material for forming the colored layer is not particularly limited as long as it satisfies the above transmission density and does not change color due to rust or the like.
  • metals such as indium, nickel, titanium, aluminum, gold, platinum, and chromium, inorganic pigments such as carbon black (CB), titanium oxide, zinc oxide, and barium sulfate, quinacridone Examples thereof include organic, azo, benzimidazolone, phthalocyanine, and anthraquinone organic pigments, light scattering members having pores therein, and the like. From the viewpoints of the above-mentioned transmission density, thickness, and electrical resistivity, it is preferable to use a metal as the colored layer forming material, and among these, nickel is more preferable.
  • a vapor deposition method such as vacuum evaporation or sputtering, film formation by plating, or a foil formed of the above material is attached. Methods etc. are available. It is more preferable to form by vacuum deposition from the point that it can be formed thinner.
  • a coating method, printing, or the like can be used. A method of transferring a colored layer formed in advance can also be used.
  • the conversion film 10 includes the piezoelectric layer 12 in which the piezoelectric particles 26 are dispersed in the viscoelastic matrix 24 containing a polymer material having a cyanoethyl group that exhibits viscoelasticity at room temperature. It has a configuration in which it is sandwiched by the lower electrode 14 and further the upper protective layer 20 and the lower protective layer 18 are sandwiched.
  • Such a conversion film 10 preferably has a maximum value at room temperature at which the loss tangent (Tan ⁇ ) at a frequency of 1 Hz as measured by dynamic viscoelasticity measurement is 0.1 or more.
  • the strain energy can be effectively diffused to the outside as heat, so that the polymer matrix and the piezoelectric particles It is possible to prevent cracks from occurring at the interface.
  • the conversion film 10 preferably has a storage elastic modulus (E ′) at a frequency of 1 Hz as measured by dynamic viscoelasticity of 10 to 30 GPa at 0 ° C. and 1 to 10 GPa at 50 ° C.
  • the conversion film 10 can have a large frequency dispersion in the storage elastic modulus (E ′) at room temperature. That is, it can behave hard for vibrations of 20 Hz to 20 kHz and soft for vibrations of several Hz or less.
  • the conversion film 10 can be equipped with moderate rigidity and mechanical strength.
  • the conversion film 10 preferably has a loss tangent (Tan ⁇ ) at 25 ° C. and a frequency of 1 kHz in a master curve obtained from dynamic viscoelasticity measurement of 0.05 or more.
  • Ton ⁇ loss tangent
  • the conversion frequency characteristic of the loudspeaker using the film 10 becomes smooth, can vary the amount of sound is also small when the lowest resonance frequency f 0 with the change in the curvature of the speaker has changed.
  • the conversion film 10 has a layer structure in which the piezoelectric layer 12, the lower thin film electrode 14 stacked on one surface of the piezoelectric layer 12, and the lower thin film electrode 14 are stacked.
  • the lower protective layer 18, the upper thin film electrode 16 stacked on the other surface of the piezoelectric layer 12, and the upper protective layer 20 stacked on the upper thin film electrode 16 are provided, the present invention is not limited thereto.
  • the thin film electrode is visible from the outside between the protective layer and the thin film electrode, for example, covering the region where the piezoelectric layer 12 is exposed and preventing a short circuit or the like. You may have the coloring layer etc. which prevent.
  • a sheet-like object 11a in which the lower electrode 14 is formed on the lower protective layer 18 is prepared.
  • the sheet-like material 11a may be produced by forming a copper thin film or the like as the lower electrode 14 on the surface of the lower protective layer 18 by vacuum deposition, sputtering, plating, or the like.
  • the lower protective layer 18 with a separator temporary support
  • PET or the like having a thickness of 25 to 100 ⁇ m can be used.
  • what is necessary is just to remove a separator just before forming a side surface insulating layer, a 2nd protective layer, etc. after thermocompression bonding of a thin film electrode and a protective layer.
  • a polymer material having a cyanoethyl group such as cyanoethylated PVA (hereinafter also referred to as viscoelastic material) and an additive polymer material having a relative dielectric constant of 10 or more such as cyanoethyl pullulan are dissolved in an organic solvent, Furthermore, a piezoelectric material particle 26 such as PZT particles is added, and a paint obtained by stirring and dispersing is prepared.
  • the organic solvent is not particularly limited, and various organic solvents such as dimethylformamide (DMF), methyl ethyl ketone, and cyclohexanone can be used.
  • the coating casting method is not particularly limited, and all known methods (coating apparatuses) such as a slide coater and a doctor knife can be used.
  • the viscoelastic material is a material that can be heated and melted, such as cyanoethylated PVA
  • the melt obtained by heating and melting the viscoelastic material and adding / dispersing the added polymer material and piezoelectric particles 26 thereto. 2B is extruded on the sheet-like material 11a shown in FIG. 2A by cooling, and cooled to have the lower electrode 14 on the lower protective layer 18 as shown in FIG. 2B.
  • a laminated body 11b formed by forming the piezoelectric layer 12 on the lower electrode 14 may be manufactured.
  • the method of preparing the coating material that becomes the piezoelectric layer 12 and after dissolving the polymer material having a cyanoethyl group, adding the added polymer material and stirring, further adding the piezoelectric particles 26.
  • the paint may be prepared by stirring.
  • a polymer piezoelectric material such as PVDF is added to the viscoelastic matrix 24 in addition to a viscoelastic material such as cyanoethylated PVA and an additive polymer material such as cyanoethyl pullulan. May be.
  • the polymer piezoelectric material added to the paint may be dissolved.
  • the polymer piezoelectric material to be added may be added to the heat-melted viscoelastic material and heat-melted. If the laminated body 11b which has the lower electrode 14 on the lower protective layer 18 and forms the piezoelectric layer 12 on the lower electrode 14 is manufactured, it is preferable to perform polarization treatment (polling) of the piezoelectric layer 12. Do.
  • the method for polarization treatment of the piezoelectric layer 12 is not particularly limited, and a known method can be used. As a preferable method of polarization treatment, the method shown in FIGS. 2C and 2D is exemplified.
  • a bar-like or wire-like shape that is movable along the upper surface 12a with a gap g of, for example, 1 mm on the upper surface 12a of the piezoelectric layer 12 of the multilayer body 11b.
  • Corona electrode 30 is provided.
  • the corona electrode 30 and the lower electrode 14 are connected to a DC power source 32.
  • a heating means for heating and holding the stacked body 11b, for example, a hot plate is prepared.
  • the piezoelectric layer 12 is heated and held at, for example, a temperature of 100 ° C. by a heating means, and a direct current of several kV, for example, 6 kV, is connected between the lower electrode 14 and the corona electrode 30 from the DC power source 32. A voltage is applied to cause corona discharge. Further, the corona electrode 30 is moved (scanned) along the upper surface 12a of the piezoelectric layer 12 while maintaining the gap g, and the piezoelectric layer 12 is polarized.
  • a direct current of several kV for example, 6 kV
  • the corona electrode 30 may be moved by using a known rod-like moving means.
  • the method for moving the corona electrode 30 is not limited. That is, the corona electrode 30 may be fixed and a moving mechanism for moving the stacked body 11b may be provided, and the stacked body 11b may be moved to perform the polarization treatment.
  • the laminate 11b may be moved by using a known sheet moving means.
  • the number of corona electrodes 30 is not limited to one, and a plurality of corona electrodes 30 may be used to perform corona poling treatment.
  • the polarization process is not limited to the corona polling process, and normal electric field poling in which a direct current electric field is directly applied to a target to be polarized can also be used.
  • normal electric field poling it is necessary to form the upper electrode 16 before the polarization treatment.
  • the sheet-like object 11c in which the upper electrode 16 was formed on the upper protective layer 20 is prepared.
  • the sheet-like material 11c may be manufactured by forming a copper thin film or the like as the upper electrode 16 on the surface of the upper protective layer 20 by vacuum deposition, sputtering, plating, or the like.
  • the upper electrode 16 is directed toward the piezoelectric layer 12, and the sheet-like material 11 c is stacked on the stacked body 11 b that has finished the polarization treatment of the piezoelectric layer 12.
  • the laminated body of the laminated body 11b and the sheet-like material 11c is subjected to thermocompression bonding with a heating press device, a pair of heating rollers or the like so as to sandwich the upper protective layer 20 and the lower protective layer 18, and the conversion film 10 Is made.
  • the conversion film 10 may be manufactured using the cut sheet-like sheet-like material or may be rolled to roll (hereinafter also referred to as RtoR).
  • RtoR is a raw material that has been processed by performing various processes such as film formation and surface treatment while pulling out the raw material from a roll formed by winding a long raw material and transporting it in the longitudinal direction. Is a manufacturing method in which the material is wound into a roll again.
  • FIG. 3A is a top view schematically showing an example of the electroacoustic transducer of the present invention
  • FIG. 3B is a sectional view taken along line BB of FIG. 3A.
  • the electroacoustic transducer 40 shown in FIGS. 3A and 3B uses the conversion film 10 as a diaphragm.
  • the electroacoustic transducer 40 is a flat speaker, and the vertical direction in FIG. 3B is the vibration direction of the conversion film 10, that is, the sound emission direction.
  • FIG. 3A is a view as seen from the vibration direction of the conversion film 10.
  • the electroacoustic transducer 40 includes the conversion film 10, a case 42, a viscoelastic support 46, and a pressing member 48.
  • the case 42 is a holding member that holds the conversion film 10 and the viscoelastic support 46 together with the pressing member 48.
  • the case 42 is a box-shaped housing that is made of plastic, metal, wood, or the like and that is open on one side.
  • the case 42 has a thin hexahedral shape, and one of the maximum surfaces is an open surface.
  • the open part has a regular square shape.
  • the case 42 accommodates a viscoelastic support 46 inside.
  • the shape of the case 42 (that is, the shape of the electroacoustic transducer) is not limited to a rectangular tube shape, and may be various shapes such as a cylindrical shape or a rectangular tube shape having a rectangular bottom surface. Can be used.
  • the viscoelastic support 46 has appropriate viscosity and elasticity, holds the conversion film 10 in a curved state, and gives a constant mechanical bias anywhere on the conversion film 10, thereby expanding and contracting the conversion film 10. This is for converting the movement into a back-and-forth movement (movement in a direction perpendicular to the surface of the conversion film) without waste.
  • the viscoelastic support 46 has a quadrangular prism shape having a bottom shape substantially the same as the bottom surface of the case 42. The height of the viscoelastic support 46 is greater than the depth of the case 42.
  • the material of the viscoelastic support 46 is not particularly limited as long as it has an appropriate viscosity and elasticity and does not hinder the vibration of the piezoelectric film and can be suitably deformed.
  • Examples include wool felt, non-woven fabric such as wool felt containing rayon and PET, foam material (foamed plastic) such as glass wool or polyurethane, polyester wool, multiple layers of paper, magnetic fluid, paint, etc. Illustrated.
  • the specific gravity of the viscoelastic support 46 is not particularly limited, and may be appropriately selected according to the type of the viscoelastic support.
  • the specific gravity is preferably 50 ⁇ 500kg / m 3, more preferably 100 ⁇ 300kg / m 3.
  • the specific gravity is preferably 10 to 100 kg / m 3 .
  • the pressing member 48 is for supporting the conversion film 10 while being pressed against the viscoelastic support 46, and is formed of a plastic, metal, wood, or the like, and is a square plate having an opening in the center. It is a shaped member.
  • the pressing member 48 has the same shape as the open surface of the case 42, and the shape of the opening is a regular square shape similar to the open portion of the case 42.
  • the viscoelastic support 46 is accommodated in the case 42, the case 42 and the viscoelastic support 46 are covered with the conversion film 10, and the case 42 is surrounded by the pressing member 48 around the conversion film 10.
  • the pressing member 48 is fixed to the case 42 while being in contact with the open surface.
  • the method for fixing the pressing member 48 to the case 42 is not particularly limited, and various known methods such as a method using screws and bolts and nuts and a method using a fixing jig can be used.
  • the viscoelastic support 46 is thicker (thickness) than the height of the inner surface of the case 42. That is, before the conversion film 10 and the pressing member 48 are fixed, the viscoelastic support 46 protrudes from the upper surface of the case 42. Therefore, in the electroacoustic transducer 40, the closer to the periphery of the viscoelastic support body 46, the lower the viscoelastic support body 46 is pressed by the conversion film 10 and the thickness thereof is reduced. That is, at least a part of the main surface of the conversion film 10 is held in a curved state. Thereby, a curved part is formed in at least a part of the conversion film 10.
  • the curved portion becomes a vibration surface.
  • the curved portion is also referred to as a vibration surface.
  • the viscoelastic support 46 is compressed in the thickness direction as it approaches the pressing member 48.
  • the static viscoelastic effect stress relaxation
  • any location of the conversion film 10 is obtained.
  • the mechanical bias can be kept constant. Thereby, since the expansion / contraction motion of the conversion film 10 is converted into the back-and-forth motion without waste, it is possible to obtain a flat electroacoustic transducer 40 that is thin and has sufficient sound volume and excellent acoustic characteristics.
  • a region of the conversion film 10 corresponding to the opening of the pressing member 48 is a curved portion that actually vibrates. That is, the pressing member 48 is a part that defines the bending portion.
  • the electroacoustic conversion unit using a conversion film having piezoelectricity is easy to increase the relative size of the diaphragm with respect to the overall size of the unit as compared with a cone speaker whose diaphragm is generally circular. Is easy. From the above viewpoint, the width of the edge of the pressing member 48 is preferably 20 mm or less, and preferably 1 mm to 10 mm.
  • the surface of the electroacoustic transducer 40 on the conversion film 10 side is similar to the curved portion. That is, the outer shape of the pressing member 48 and the shape of the opening are preferably similar.
  • the pressing force of the viscoelastic support 46 by the conversion film 10 is not particularly limited, but is 0.005 to 1.0 MPa, particularly 0.02 in terms of surface pressure at a position where the surface pressure is low.
  • the pressure is preferably about 0.2 MPa.
  • the thickness of the viscoelastic support 46 is not particularly limited, but the thickness before pressing is preferably 1 to 100 mm, particularly 10 to 50 mm.
  • the viscoelastic support 46 having viscoelasticity is used.
  • the present invention is not limited to this, and any structure that uses at least an elastic support having elasticity may be used.
  • it is good also as a structure which replaces with the viscoelastic support body 46 and has an elastic support body which has elasticity.
  • the elastic support include natural rubber and various synthetic rubbers.
  • the electroacoustic transducer 40 shown to FIG. 3A is pressing the whole periphery of the conversion film 10 against the case 42 with the press member 48
  • this invention is not limited to this. That is, the electroacoustic transducer using the conversion film 10 does not have the pressing member 48, and the conversion film 10 is attached to the case 42 by screws, bolts, nuts, jigs, etc. at four corners of the case 42.
  • a configuration formed by pressing / fixing to the upper surface can also be used.
  • an O-ring or the like may be interposed between the case 42 and the conversion film 10.
  • the electroacoustic transducer using the conversion film 10 may not have the case 42 that houses the viscoelastic support 46.
  • a viscoelastic support is placed on a rigid support plate, the conversion film 10 is placed so as to cover the viscoelastic support, and a pressing member similar to the above is placed on the periphery.
  • a configuration in which the viscoelastic support is pressed together with the pressing member by fixing the pressing member to the support plate with a screw or the like can also be used.
  • the size of the support plate may be larger than that of the viscoelastic support, and the material of the support plate is an electroacoustic transducer by using various vibration plates such as polystyrene, foamed PET, or carbon fiber. The effect of further amplifying the vibration can be expected.
  • the electroacoustic transducer is not limited to the configuration of pressing the periphery, and for example, a configuration in which the center of the laminated body of the viscoelastic support 46 and the conversion film 10 is pressed by some means can be used. is there. That is, as long as the electroacoustic transducer is configured to be held in a curved state of the conversion film 10, various configurations can be used. Or it is good also as a structure which affixes the tension
  • case 42 It is good also as a structure which fixes the edge part of a conversion film on the back surface side of the case 42 using the conversion film 10 larger than the opening surface. That is, the case 42 and the viscoelastic support 46 arranged in the case 42 are covered with the conversion film 10 larger than the opening surface of the case 42, and the end of the conversion film 10 is pulled to the back side of the case 42.
  • the conversion film 10 may be pressed against the viscoelastic support 46 to apply a tension to bend, and the end of the conversion film may be fixed on the back side of the case 42.
  • an airtight case is used, the open end of the case is covered and closed with a conversion film, gas is introduced into the case, pressure is applied to the conversion film, and the structure is held in an inflated shape. It is good.
  • the electroacoustic transducer 56 shown in FIG. 4C is illustrated.
  • an airtight material is used as a similar case 42, and a pipe 42a for introducing air into the case 42 is provided.
  • An O-ring 57 is provided on the upper surface of the open end of the case 42, and the case 42 is covered with the conversion film 10 so as to close the open surface.
  • a frame-shaped holding lid 58 having a substantially L-shaped cross section having an inner periphery substantially the same as the outer periphery of the case 42 is fitted to the outer periphery of the case 42 (FIG. 4B).
  • the O-ring 57 is omitted).
  • air is introduced from the pipe 42a into the case 42 (closed space by the case 42 and the conversion film 10), pressure is applied to the conversion film 10, and the state is expanded in a convex shape.
  • the electroacoustic transducer 56 is held.
  • the pipe 42a may be fixed or detachable. When removing the pipe 42a, it is natural that the attaching / detaching portion of the pipe is hermetically closed.
  • FIG. 4C a pressure is applied in the case to hold it in a bulged state, but as shown in FIG. 4D, a case having the same airtightness as FIG. 4C is used.
  • the open end may be covered and closed with a conversion film, the inside of the case may be evacuated, negative pressure is applied to the conversion film, and the concave shape may be retained.
  • the conversion film 10 was pressed by the viscoelastic support body 46, it was set as the structure hold
  • the configuration for holding the conversion film 10 in a curved state there is no particular limitation on the configuration for holding the conversion film 10 in a curved state.
  • a formation method of a convex part The processing method of various well-known resin films can be utilized.
  • the convex portion can be formed by a forming method such as a vacuum pressure molding method or embossing.
  • the electroacoustic conversion film of the present invention can be suitably used as a speaker in combination with a flexible display such as an organic EL display. Moreover, you may combine the electroacoustic conversion film of this invention with the screen for projectors.
  • the designability and entertainment of a conversion film can be improved.
  • the conversion film as a speaker with a screen or a flexible display, it is possible to reproduce sound from the direction in which the image is displayed, and to improve the sense of reality.
  • the projector screen since the projector screen is flexible, it can have a curvature. By giving the curvature to the image display surface, the distance from the observer to the screen can be made substantially uniform at the center and the end of the screen, and the sense of reality can be improved.
  • the curvature is given to the image display surface in this way, the projected image is distorted. Therefore, it is preferable to perform image processing on the image data to be projected so as to reduce distortion in accordance with the curvature of the image display surface.
  • Example 1 The conversion film 10 shown in FIG. 1 was produced by the method shown in FIGS. 2A to 2E.
  • cyanoethylated PVA CR-V manufactured by Shin-Etsu Chemical Co., Ltd.
  • cyanoethyl pullulan C-S manufactured by Shin-Etsu Chemical Co., Ltd.
  • MEK methyl ethyl ketone
  • cyclohexanone 50 wt% each
  • PZT particles as piezoelectric particles were added to the solution at the following composition ratio and dispersed with a propeller mixer (rotation speed: 2000 rpm) to prepare a coating material for forming the piezoelectric layer 12.
  • sheet-like materials 11a and 11c were prepared by vacuum-depositing a 0.1 ⁇ m thick copper thin film on a 4 ⁇ m thick PET film. That is, in this example, the upper electrode 16 and the lower electrode 14 are copper-deposited thin films having a thickness of 0.1 m, and the upper protective layer 20 and the lower protective layer 18 are PET films having a thickness of 4 ⁇ m. In addition, in order to obtain good handling during the process, a PET film with a 50 ⁇ m thick separator (temporary support PET) was used, and after the thermocompression bonding of the thin film electrode and the protective layer, the separator of each protective layer was removed. Removed.
  • temporary support PET temporary support PET
  • the laminated body 11b which has the lower electrode 14 made of copper on the lower protective layer 18 made of PET, and formed the piezoelectric layer 12 (piezoelectric layer) having a thickness of 20 ⁇ m thereon was produced. .
  • the piezoelectric layer 12 of the laminate 11b was polarized by the above-described corona poling shown in FIGS. 2C and 2D.
  • the polarization treatment was performed by setting the temperature of the piezoelectric layer 12 to 100 ° C. and applying a DC voltage of 6 kV between the lower electrode 14 and the corona electrode 30 to cause corona discharge.
  • a mixture of cyanoethylated pullulan and cyanoethylated PVA (CR-M manufactured by Shin-Etsu Chemical Co., Ltd.) is applied to the upper layer 16b (copper thin film side) to a thickness of 0.3 ⁇ m on the laminate 11b subjected to polarization treatment.
  • the sheet 11c was laminated with the coated surface of the film directed toward the piezoelectric layer 12.
  • the laminated body of the laminated body 11b and the sheet-like material 11c is thermocompression-bonded at 120 ° C. using a laminator device, so that the piezoelectric body layer 12 and the upper electrode 16 and the lower electrode 14 are bonded to make a flat conversion.
  • Film 10 was produced.
  • Example 2 An electroacoustic conversion film 10 was produced in the same manner as in Example 1 except that the ratio of the additive polymer material (cyanoethyl pullulan) in the viscoelastic matrix 24 was changed as shown in Table 2 below.
  • Example 7 An electroacoustic conversion film 10 was produced in the same manner as in Example 1 except that cyanoethylcellulose was used as the additive polymer material and the ratio of the additive polymer material (cyanoethylcellulose) in the viscoelastic matrix 24 was 20% by mass. .
  • Example 8 As the sheet-like materials 11a and 11c, a nickel thin film having a thickness of 20 nm was formed on a PET film having a thickness of 4 ⁇ m by vacuum deposition, and a copper thin film having a thickness of 0.1 ⁇ m was further vacuum deposited on the nickel thin film.
  • An electroacoustic conversion film 10 was produced in the same manner as in Example 6 (the ratio of the additive polymer material of 20% by mass) except that the material was used.
  • Example 9 As the sheet-like materials 11a and 11c, a chromium thin film having a thickness of 20 nm was formed on a PET film having a thickness of 4 ⁇ m by vacuum deposition, and a copper thin film having a thickness of 0.1 ⁇ m was further vacuum deposited on the chromium thin film.
  • An electroacoustic conversion film 10 was produced in the same manner as in Example 6 except that a material was used.
  • Example 10 An electroacoustic conversion film 10 was produced in the same manner as in Example 6 except that an aramid film having a thickness of 4 ⁇ m was used as the protective layer.
  • Example 11 An electroacoustic conversion film 10 was produced in the same manner as in Example 4 except that BaTiO 3 particles were added as dielectric particles to the coating material for forming the piezoelectric layer 12.
  • BaTiO 3 particles As the BaTiO 3 particles, BT-05 (manufactured by Sakai Chemical Co., Ltd., average particle size 0.5 ⁇ m) was used. The volume fraction of the piezoelectric particles in the piezoelectric layer was 15%.
  • Example 12 An electroacoustic conversion film 10 was produced in the same manner as in Example 1 except that nitrile rubber was used as the additive polymer material, and the ratio of the additive polymer material (nitrile rubber) in the viscoelastic matrix 24 was 20% by mass. .
  • the electroacoustic conversion film 10 is the same as in Example 1 except that polyvinylidene fluoride is used as the additive polymer material, and the ratio of the additive polymer material (polyvinylidene fluoride) in the viscoelastic matrix 24 is 20% by mass. Was made.
  • Example 8 The electroacoustic conversion film 10 is produced in the same manner as in Example 1 except that chloroprene rubber is used as the additive polymer material and the ratio of the additive polymer material (chloroprene rubber) in the viscoelastic matrix 24 is 20% by mass. did.
  • Table 1 shows the relative dielectric constant, loss tangent and volume resistance at 25 ° C. and 20 Hz of the additive polymer material used in each example and comparative example.
  • the sound pressure level of the produced electroacoustic transducer was measured to determine the sound pressure sensitivity. Specifically, a microphone is arranged at a position 0.1 m away from the center of the conversion film 10 of the electroacoustic transducer 56b, and 1 kHz, 10 V op is provided between the upper electrode and the lower electrode of the electroacoustic transducer. The sound pressure level was measured by inputting a sine wave. Based on the difference from the sound pressure level of Comparative Example 1, evaluation was performed as follows. A case where the difference in sound pressure level from Comparative Example 1 is +2 dB or more is “A”.
  • the difference in sound pressure level from Comparative Example 1 is “B” when the difference is not less than +1 dB and less than +2 dB.
  • a case where the difference in sound pressure level from Comparative Example 1 is not less than ⁇ 1 dB and less than +1 dB is “C”.
  • D when the sound pressure level difference from Comparative Example 1 is less than ⁇ 1 dB. It was evaluated.
  • ⁇ Frequency band> The sound pressure level-frequency characteristics of the produced electroacoustic transducer were measured by sine wave sweep measurement using a constant current type power amplifier. Note that the measurement microphone was placed 10 cm above the center of the speaker. The frequency was measured between 20 Hz and 20 kHz. From the measurement result of this sound pressure level-frequency characteristic, the local maximum value (peak) of the sound pressure level and the local minimum value (dip) immediately adjacent to the high frequency side of the peak are read, and the difference between these peaks and dip is obtained. Based on the following evaluations. “A” when the difference between the peak and the dip is 20 dB or less “B” when the difference between the peak and dip is more than 20 dB and less than 25 dB “C” when the difference between the peak and the dip exceeds 25 dB
  • the withstand voltage of the conversion film was measured using the produced electroacoustic transducer.
  • An AC voltage was applied to the upper thin film electrode and the lower thin film electrode of the conversion film incorporated in the electroacoustic transducer, and the frequency measured as the withstand voltage value of the AC effective voltage when an abnormality occurred in the appearance of the film was 10 kHz. It was. Based on the measured withstand voltage value, it evaluated as follows. The case where the difference in withstand voltage value from Comparative Example 1 is 10 V or more is “A”. A case where the difference in withstand voltage value from Comparative Example 1 is 5 V or more and less than 10 V is “B”.
  • the examples of the electroacoustic conversion film of the present invention have higher evaluations of sound pressure and frequency band than the comparative examples. Further, from the comparison with Examples 1 to 6, it can be seen that the proportion of the added polymer material is preferably 10% to 30%, more preferably 15% to 20%. In addition, it can be seen from the comparison between Examples 4, 7, and 12 that the use of an additive polymer material having a loss tangent at 25 ° C. and 20 Hz of 0.05 or less improves the sound pressure. In addition, it can be seen that it is preferable that the volume resistance of the additive polymer material is 1 ⁇ 10 12 ⁇ ⁇ cm or more because the withstand voltage is improved.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Piezo-Electric Transducers For Audible Bands (AREA)

Abstract

L'invention concerne un film de conversion électro-acoustique qui permet d'améliorer des niveaux de pression acoustique en augmentant l'efficacité de conversion entre l'électricité et le son, et d'augmenter la bande passante en réduisant des irrégularités de pic et de creux dans le niveau de pression acoustique de la caractéristique de fréquence. Le film de conversion électro-acoustique selon l'invention comprend : un corps piézo-électrique composite polymère formé en dispersant des particules piézo-électriques dans une matrice viscoélastique contenant un matériau polymère ayant un groupe cyanoéthyle et une caractéristique viscoélastique à température ambiante ; deux électrodes à film mince stratifiées sur les deux surfaces du corps piézo-électrique composite polymère ; et deux couches de protection stratifiées sur chacune des deux électrodes à film mince, la matrice viscoélastique contenant un additif polymère qui est un matériau polymère dont la constante diélectrique relative est au moins égale à 10.
PCT/JP2016/074258 2015-08-20 2016-08-19 Film de conversion électro-acoustique WO2017030192A1 (fr)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20210258693A1 (en) * 2018-11-06 2021-08-19 Yamaha Corporation Speaker Diaphragm
WO2021200455A1 (fr) * 2020-03-31 2021-10-07 富士フイルム株式会社 Élément piézoélectrique en couches et transducteur électroacoustique
KR20220004188A (ko) * 2019-06-28 2022-01-11 후지필름 가부시키가이샤 고분자 복합 압전체, 압전 필름, 압전 스피커, 플렉시블 디스플레이
KR20220007125A (ko) * 2019-06-28 2022-01-18 후지필름 가부시키가이샤 고분자 복합 압전체, 압전 필름, 압전 스피커, 플렉시블 디스플레이
US11765518B2 (en) 2020-11-25 2023-09-19 Lg Display Co., Ltd. Sound apparatus and display apparatus including the same

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Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20210258693A1 (en) * 2018-11-06 2021-08-19 Yamaha Corporation Speaker Diaphragm
US11974110B2 (en) * 2018-11-06 2024-04-30 Yamaha Corporation Speaker diaphragm
KR20220004188A (ko) * 2019-06-28 2022-01-11 후지필름 가부시키가이샤 고분자 복합 압전체, 압전 필름, 압전 스피커, 플렉시블 디스플레이
KR20220007125A (ko) * 2019-06-28 2022-01-18 후지필름 가부시키가이샤 고분자 복합 압전체, 압전 필름, 압전 스피커, 플렉시블 디스플레이
KR102600732B1 (ko) 2019-06-28 2023-11-09 후지필름 가부시키가이샤 고분자 복합 압전체, 압전 필름, 압전 스피커, 플렉시블 디스플레이
KR102612144B1 (ko) 2019-06-28 2023-12-08 후지필름 가부시키가이샤 고분자 복합 압전체, 압전 필름, 압전 스피커, 플렉시블 디스플레이
WO2021200455A1 (fr) * 2020-03-31 2021-10-07 富士フイルム株式会社 Élément piézoélectrique en couches et transducteur électroacoustique
JPWO2021200455A1 (fr) * 2020-03-31 2021-10-07
JP7386324B2 (ja) 2020-03-31 2023-11-24 富士フイルム株式会社 積層圧電素子および電気音響変換器
US11765518B2 (en) 2020-11-25 2023-09-19 Lg Display Co., Ltd. Sound apparatus and display apparatus including the same
US12022257B2 (en) 2020-11-25 2024-06-25 Lg Display Co., Ltd. Sound apparatus and display apparatus including the same

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