WO2023048022A1 - 圧電素子および圧電スピーカー - Google Patents

圧電素子および圧電スピーカー Download PDF

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Publication number
WO2023048022A1
WO2023048022A1 PCT/JP2022/034230 JP2022034230W WO2023048022A1 WO 2023048022 A1 WO2023048022 A1 WO 2023048022A1 JP 2022034230 W JP2022034230 W JP 2022034230W WO 2023048022 A1 WO2023048022 A1 WO 2023048022A1
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Prior art keywords
piezoelectric
piezoelectric element
layer
film
thickness
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PCT/JP2022/034230
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English (en)
French (fr)
Japanese (ja)
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裕介 香川
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富士フイルム株式会社
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Priority to CN202280062540.5A priority Critical patent/CN117981356A/zh
Publication of WO2023048022A1 publication Critical patent/WO2023048022A1/ja

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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
    • H10N30/01—Manufacture or treatment
    • H10N30/07—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base
    • H10N30/072—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base by laminating or bonding of piezoelectric or electrostrictive bodies
    • 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

Definitions

  • the present invention relates to a piezoelectric element and a piezoelectric speaker using this piezoelectric element.
  • exciters which are attached to various articles in contact with them to vibrate the articles to produce sound, are used in various applications. For example, in an office, by attaching an exciter to a conference table, a whiteboard, a screen, or the like, sound can be output instead of a speaker during presentations, conference calls, and the like.
  • a vehicle such as an automobile
  • by attaching an exciter to the console, A-pillar, ceiling, or the like it is possible to produce guide sounds, warning sounds, music, and the like.
  • a vehicle approach notification sound can be emitted from the bumper or the like.
  • variable elements that generate vibration in such exciters, combinations of coils and magnets, vibration motors such as eccentric motors and linear resonance motors, and the like are known. These variable elements are difficult to thin.
  • vibration motors have drawbacks such as the need to increase the mass in order to increase the vibration force, difficulty in frequency modulation for adjusting the degree of vibration, and slow response speed.
  • speakers are also required to be flexible in response to the demand for flexible displays.
  • Patent Literature 1 describes a laminated piezoelectric element in which a plurality of piezoelectric films having a piezoelectric layer sandwiched between two thin film electrodes are laminated.
  • the piezoelectric films in this laminated piezoelectric element are polarized in the thickness direction, and the polarization directions of adjacent piezoelectric films are opposite to each other.
  • the piezoelectric film expands and contracts in the plane direction by energizing the piezoelectric film.
  • this laminated piezoelectric element to the diaphragm as an exciter, the expansion and contraction motion of the laminated piezoelectric film causes the diaphragm to flex and vibrate in a direction perpendicular to the plate surface, and the diaphragm outputs sound.
  • a piezoelectric speaker can be realized.
  • a piezoelectric film is folded in a bellows shape to stack a plurality of piezoelectric films.
  • a piezoelectric film is folded in a bellows shape to stack a plurality of piezoelectric films.
  • an external device such as a power supply for each individual piezoelectric film.
  • the piezoelectric film is folded to laminate a plurality of layers, since there is only one piezoelectric film, the connection between the electrode layer and an external device such as a power source can be made at one point.
  • the laminated piezoelectric element when used as an exciter, it is necessary to adhere the laminated piezoelectric element to the diaphragm as described above.
  • the lamination piezoelectric element and the diaphragm are adhered by, for example, pressing the lamination piezoelectric element against the diaphragm via an adhesive such as an adhesive.
  • the piezoelectric film in which the piezoelectric film is folded and laminated, surface pressure is applied to the piezoelectric film by pressing at this time.
  • this surface pressure is applied to the folded portion of the piezoelectric film, the piezoelectric film is burdened, and in some cases, the electrode layer and/or the piezoelectric layer may break at the folded portion.
  • the piezoelectric film uses, as a piezoelectric layer, a polymer composite piezoelectric body in which piezoelectric particles are dispersed in a polymer material, for example. Therefore, this laminated piezoelectric element has very good flexibility. Therefore, by attaching this laminated piezoelectric element to a flexible diaphragm, it is possible to realize a flexible piezoelectric speaker that can be bent and wound.
  • the laminated piezoelectric element is also wound together with the diaphragm. During this winding, surface pressure is applied to the piezoelectric film at the folded portion as before, and in some cases, , the electrode layer and/or the piezoelectric layer break.
  • An object of the present invention is to solve the problems of the prior art, and to provide a piezoelectric element in which piezoelectric films are folded and laminated, and when a pressure is applied, the electrode layer is bent at the folded portion of the piezoelectric film. It is an object of the present invention to provide a piezoelectric element capable of preventing breakage of a wire, etc., and a piezoelectric speaker using the piezoelectric element.
  • the present invention has the following configurations.
  • [1] In a piezoelectric element in which a plurality of piezoelectric films are laminated by folding a flexible piezoelectric film, Having an adhesive layer for attaching the laminated and adjacent piezoelectric films, When the thickness of the adhesive layer at the thickest part of the piezoelectric element is t, and the shortest distance between the end of the folded part of the piezoelectric film and the thickest part of the piezoelectric element is L, "L ⁇ 50*t" is satisfied.
  • a piezoelectric element characterized by filling: [2] having a rectangular shape when viewed from the lamination direction of the piezoelectric film; The piezoelectric element according to [1], wherein the long sides of the rectangle are aligned with folding lines of the piezoelectric film. [3] The piezoelectric element according to [1] or [2], wherein the thickness of the thickest portion is 115% or more of the thickness of the folded portion of the piezoelectric film. [4] Any one of [1] to [3], wherein the piezoelectric film has a piezoelectric layer, electrode layers provided on both sides of the piezoelectric layer, and protective layers provided covering the electrode layers. The piezoelectric element according to .
  • the present invention it is possible to prevent the electrode layers and the like from being broken at the folded portion of the piezoelectric film when pressure is applied to the piezoelectric element in which the piezoelectric film is folded and laminated.
  • FIG. 1 is a diagram conceptually showing an example of the piezoelectric element of the present invention.
  • FIG. 2 is a conceptual diagram for explaining an example of the piezoelectric element of the present invention.
  • FIG. 3 is a conceptual diagram for explaining another example of the piezoelectric element of the present invention.
  • FIG. 4 is a diagram conceptually showing an example of a piezoelectric film used in the piezoelectric element of the present invention.
  • FIG. 5 is a conceptual diagram for explaining an example of a method for producing a piezoelectric film.
  • FIG. 6 is a conceptual diagram for explaining an example of a method for producing a piezoelectric film.
  • FIG. 7 is a conceptual diagram for explaining an example of a method for producing a piezoelectric film.
  • FIG. 1 is a diagram conceptually showing an example of the piezoelectric element of the present invention.
  • FIG. 2 is a conceptual diagram for explaining an example of the piezoelectric element of the present invention.
  • FIG. 3 is
  • FIG. 8 is a conceptual diagram for explaining the piezoelectric element of the present invention.
  • FIG. 9 is a conceptual diagram for explaining the piezoelectric element of the present invention.
  • FIG. 10 is a conceptual diagram for explaining an example of the method for manufacturing the piezoelectric element of the present invention.
  • FIG. 11 is a diagram conceptually showing another example of the piezoelectric element of the present invention.
  • FIG. 12 is a diagram conceptually showing an example of the piezoelectric speaker of the present invention.
  • a numerical range represented by "to” means a range including the numerical values before and after “to” as lower and upper limits.
  • the first and the second attached to the electrode layer, the protective layer, etc. are used to distinguish between two members that are basically the same, and to explain the piezoelectric element and piezoelectric speaker of the present invention. are attached for convenience. Therefore, the first and second parts of these members have no technical meaning, and are irrelevant to the actual usage conditions and mutual positional relationships.
  • FIG. 1 conceptually shows an example of the piezoelectric element of the present invention.
  • the upper part shows a front view of the piezoelectric element 10
  • the lower part shows a plan view.
  • the front view is a view of the piezoelectric element of the present invention as viewed in the surface direction of a piezoelectric film, which will be described later.
  • a plan view is a view of the piezoelectric element of the present invention as viewed from the lamination direction of the piezoelectric films, which will be described later.
  • the plan view is a view of the piezoelectric element viewed from a direction perpendicular to the main surface of the piezoelectric film 12 .
  • the principal surface is the largest surface of a sheet (film, plate, layer), and is usually both sides of the sheet in the thickness direction.
  • plan view the case where the piezoelectric element of the present invention is viewed from the same direction as the plan view is also referred to as "plan view” for convenience.
  • shape of the piezoelectric element of the present invention when viewed from above, that is, the shape of the piezoelectric element of the present invention in a plan view is also referred to as a "planar shape" for convenience.
  • a piezoelectric element 10 shown in FIG. 1 is obtained by laminating a plurality of piezoelectric films 12 by folding a flexible piezoelectric film 12 several times in a bellows shape.
  • the piezoelectric film 12 has a first electrode layer 28 on one surface of the piezoelectric layer 26 and a second electrode layer 30 on the other surface, and a first protective layer 32 on the surface of the first electrode layer 28 and a second electrode layer 28 .
  • a second protective layer 34 is provided on the surface of the layers 30, respectively.
  • the adjacent piezoelectric films 12 laminated by folding are attached by the adhesive layer 20 .
  • the illustrated piezoelectric element 10 is formed by laminating five layers of piezoelectric films 12 by folding a rectangular (rectangular) piezoelectric film 12 four times at regular intervals. Therefore, the planar shape of the piezoelectric element 10 is rectangular.
  • the folding line formed by folding the piezoelectric film 12 is aligned with the longitudinal direction in the planar shape of the piezoelectric element 10, but You can match the direction.
  • the fold line formed by folding the piezoelectric film 12, that is, the line of the outer top of the end of the folded portion is also referred to as a "ridge line" for convenience.
  • the piezoelectric element 10 having a rectangular planar shape of 20 ⁇ 5 cm will be described.
  • the piezoelectric element 10 of the present invention is a 20 cm piezoelectric element having a ridgeline in the longitudinal direction, which is obtained by folding a rectangular piezoelectric film 12 of 20 cm by 25 cm by 5 cm in the direction of each side of 25 cm. 10 is fine.
  • the piezoelectric element 10 of the present invention is obtained by folding a rectangular piezoelectric film 12 of 100 cm by 5 cm by 20 cm in the direction of each side of 100 cm. may be used. 2 and 3, the thickest portion of the piezoelectric element 10, which will be described later, is omitted.
  • the piezoelectric element 10 of the present invention preferably has a rectangular planar shape and has a ridge line, that is, a folded end line (folded line) that coincides with the long side.
  • a folded end line folded line
  • Such a configuration is preferable in that the piezoelectric element 10 can be manufactured easily, the productivity can be increased, and the current density at the folded portion (bent portion) can be reduced.
  • the piezoelectric element 10 shown in FIGS. 1 to 3 preferably has a rectangular planar shape, which is produced by folding a rectangular piezoelectric film 12 .
  • the shape of the piezoelectric film 12 is not limited to rectangular, and various shapes can be used. Examples include circles, rounded rectangles (ovals), ellipses, and polygons such as hexagons.
  • the piezoelectric element 10 is obtained by laminating the piezoelectric film 12 by folding it multiple times.
  • five layers of the piezoelectric film 12 are laminated by folding the piezoelectric film 12 four times.
  • the laminated and adjacent piezoelectric films 12 are attached by the adhesive layer 20 .
  • the piezoelectric element 10 of the present invention by laminating a plurality of piezoelectric films 12 and adhering the adjacent piezoelectric films 12 in this manner, the piezoelectric element 10 can be manufactured as a piezoelectric element as compared with the case of using a single piezoelectric film. You can increase the elasticity.
  • a diaphragm which will be described later, can be bent with a large force to output sound with a high sound pressure.
  • t is the thickness of the adhesive layer 20 at the thickest portion M where the piezoelectric element is the thickest
  • t is the thickness of the adhesive layer 20
  • 'L ⁇ 50*t' is satisfied when L is the shortest distance of . Since the piezoelectric element 10 of the present invention has such a configuration, when the piezoelectric element is pressed in the stacking direction, such as when the piezoelectric element 10 is adhered to a diaphragm to be described later, the piezoelectric film 12 is folded back. At the part, the piezoelectric layer 26 and the electrode layer are prevented from breaking. This point will be described in detail later.
  • the number of layers of the piezoelectric film 12 in the piezoelectric element 10 is not limited to five layers in the illustrated example.
  • the piezoelectric element 10 of the present invention may be a laminate of four or less piezoelectric films 12 in which the piezoelectric film 12 is folded three times or less, or a laminate of six or more layers in which the piezoelectric film 12 is folded five times or more.
  • the piezoelectric film 12 may be laminated.
  • the number of layers of the piezoelectric film 12 is not limited, but preferably 2 to 10 layers, more preferably 3 to 7 layers.
  • the piezoelectric films 12 adjacent to each other in the lamination direction are adhered by the adhesion layer 20 .
  • the expansion and contraction of each piezoelectric film 12 can be directly transmitted, and the piezoelectric films 12 can be stacked as a laminate and driven without waste. becomes possible.
  • the sticking layer 20 may be a layer made of an adhesive (adhesive material), a layer made of an adhesive (adhesive material), or a layer made of a material having the characteristics of both an adhesive and an adhesive.
  • the adhesive is a sticking agent that has fluidity at the time of bonding and then becomes solid.
  • the pressure-sensitive adhesive is a gel-like (rubber-like) soft solid that is adhered to each other and does not change its gel-like state afterward.
  • the adhesive layer 20 may be formed by applying an adhesive having fluidity such as a liquid, or may be formed by using a sheet-like adhesive.
  • the piezoelectric element 10 is used as an exciter as an example.
  • the piezoelectric element 10 expands and contracts itself by expanding and contracting the laminated plural piezoelectric films 12, and for example, bends and vibrates the diaphragm 62 as described later to generate sound. Therefore, in the piezoelectric element 10, it is preferable that the expansion and contraction of each laminated piezoelectric film 12 is directly transmitted. If a viscous substance that relaxes vibration exists between the piezoelectric films 12, the efficiency of transmission of the energy of expansion and contraction of the piezoelectric films 12 is lowered, and the driving efficiency of the piezoelectric element 10 is lowered.
  • the sticking layer 20 is preferably an adhesive layer made of an adhesive that provides a solid and hard sticking layer 20 rather than a sticky layer made of an adhesive.
  • a more preferable adhesive layer 20 is an adhesive layer made of a thermoplastic type adhesive such as a polyester adhesive and a styrene-butadiene rubber (SBR) adhesive. Adhesion, unlike sticking, is useful in seeking high adhesion temperatures. Further, a thermoplastic type adhesive is suitable because it has "relatively low temperature, short time, and strong adhesion".
  • the thickness of the adhesive layer 20 is not limited, and a thickness capable of exhibiting sufficient adhesive force may be appropriately set according to the material forming the adhesive layer 20 .
  • the adhesive layer 20 is thick and rigid, it may restrict the expansion and contraction of the piezoelectric film 12 .
  • the adhesive layer 20 is preferably thinner than the piezoelectric layer 26 . That is, in the piezoelectric element 10, the adhesive layer 20 is preferably hard and thin.
  • the thickness of the adhesive layer 20 is preferably 0.1 to 50 ⁇ m, more preferably 0.1 to 30 ⁇ m, even more preferably 0.1 to 10 ⁇ m after being attached.
  • piezoelectric element of the present invention various known piezoelectric films 12 can be used as long as the piezoelectric film 12 is flexible enough to be bent and stretched.
  • having flexibility is synonymous with having flexibility in general interpretation, and indicates that it is possible to bend and bend, specifically , indicating that it can be bent and stretched without fracture and damage.
  • the piezoelectric film 12 preferably has electrode layers provided on both sides of the piezoelectric layer 26 and protective layers provided to cover the electrode layers.
  • FIG. 4 conceptually shows an example of the piezoelectric film 12 in a sectional view. In FIG. 4 and the like, hatching is omitted in order to simplify the drawing and clearly show the configuration.
  • cross section refers to a cross section in the thickness direction of the piezoelectric film. The thickness direction of the piezoelectric film is the stacking direction of the piezoelectric film.
  • the piezoelectric film 12 of the illustrated example includes a piezoelectric layer 26 , a first electrode layer 28 laminated on one surface of the piezoelectric layer 26 , and a first electrode layer 28 laminated on the first electrode layer 28 .
  • 1 protective layer 32 a second electrode layer 30 laminated on the other surface of the piezoelectric layer 26 , and a second protective layer 34 laminated on the second electrode layer 30 .
  • the piezoelectric films 12 are laminated by folding one piezoelectric film 12 . Therefore, although a plurality of piezoelectric films 12 are laminated, the electrodes for driving the piezoelectric elements 10, that is, the piezoelectric films 12, can be led out in one place for each electrode layer, which will be described later. As a result, the configuration of the piezoelectric element 10 and the wiring of the electrodes can be simplified, and productivity is also excellent. In addition, since one sheet of piezoelectric film 12 is folded and laminated, the electrode layers facing adjacent piezoelectric films due to lamination have the same polarity.
  • the piezoelectric layer 26 is preferably a polymer composite piezoelectric body containing piezoelectric particles 40 in a polymer matrix 38 containing a polymer material, as conceptually shown in FIG. .
  • the polymer composite piezoelectric body (piezoelectric layer 26) preferably satisfies the following requirements.
  • normal temperature is 0 to 50°C.
  • Flexibility For example, when gripping a loosely bent state like a document like a newspaper or magazine for portable use, it is constantly subjected 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 correspondingly large bending stress is generated, and cracks occur at the interface between the polymer matrix and the piezoelectric particles, which may eventually lead to destruction. Therefore, the polymer composite piezoelectric body is required to have appropriate softness.
  • the lowest resonance frequency f 0 of the speaker diaphragm is given by the following equation.
  • s is the stiffness of the vibration system and m is the mass.
  • the polymer composite piezoelectric body is required to behave hard against vibrations of 20 Hz to 20 kHz and softly against vibrations of several Hz or less. Also, the loss tangent of the polymer composite piezoelectric body is required to be moderately large with respect to vibrations of all frequencies of 20 kHz or less.
  • polymer solids have a viscoelastic relaxation mechanism, and as temperature rises or frequency falls, large-scale molecular motion causes a decrease (relaxation) in storage elastic modulus (Young's modulus) or a maximum loss elastic modulus (absorption). is observed as Among them, the relaxation caused by the micro-Brownian motion of the molecular chains in the amorphous region is called principal dispersion, and a very large relaxation phenomenon is observed.
  • the temperature at which this primary dispersion occurs is the glass transition point (Tg), and the viscoelastic relaxation mechanism appears most prominently.
  • the polymer composite piezoelectric body (piezoelectric layer 26), by using a polymer material having a glass transition point at room temperature, in other words, a polymer material having viscoelasticity at room temperature, as a matrix, vibration of 20 Hz to 20 kHz is suppressed.
  • a polymer composite piezoelectric material that is hard at first and behaves softly with respect to slow vibrations of several Hz or less.
  • the polymer material that forms the polymer matrix 38 preferably has a maximum loss tangent Tan ⁇ of 0.5 or more at a frequency of 1 Hz in a dynamic viscoelasticity test at room temperature.
  • the storage elastic modulus (E') at a frequency of 1 Hz measured by dynamic viscoelasticity measurement of the polymer material forming the polymer matrix 38 is 100 MPa or more at 0°C and 10 MPa or less at 50°C.
  • the polymer material that forms the polymer matrix 38 has a dielectric constant of 10 or more at 25°C.
  • a voltage is applied to the polymer composite piezoelectric material, a higher electric field is applied to the piezoelectric particles in the polymer matrix, so a large amount of deformation can be expected.
  • the polymer material in consideration of ensuring good moisture resistance and the like, it is also suitable for the polymer material to have a dielectric constant of 10 or less at 25°C.
  • Polymer materials that satisfy these conditions include cyanoethylated polyvinyl alcohol (cyanoethylated PVA), polyvinyl acetate, polyvinylidene chloride core acrylonitrile, polystyrene-vinylpolyisoprene block copolymer, polyvinylmethylketone, and polybutyl. Methacrylate and the like are preferably exemplified. Commercially available products such as Hybler 5127 (manufactured by Kuraray Co., Ltd.) can also be suitably used as these polymer materials.
  • Hybler 5127 manufactured by Kuraray Co., Ltd.
  • the piezoelectric layer 26 preferably uses a polymer material having a cyanoethyl group as the polymer matrix 38, and more preferably uses cyanoethylated PVA.
  • the above-mentioned polymeric materials represented by cyanoethylated PVA are collectively referred to as "polymeric materials having viscoelasticity at room temperature".
  • These polymer materials having viscoelasticity at room temperature may be used alone or in combination (mixed).
  • the polymer matrix 38 of the piezoelectric layer 26 may be made of a combination of multiple polymer materials, if necessary. That is, for the polymer matrix 38 constituting the polymer composite piezoelectric body, in addition to the above-described polymer material having viscoelasticity at room temperature, other materials may be used as necessary for the purpose of adjusting dielectric properties and mechanical properties. dielectric polymer material may be added.
  • dielectric polymer materials examples include polyvinylidene fluoride, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, and polyvinylidene fluoride-trifluoroethylene copolymer.
  • fluorine-based polymers such as polyvinylidene fluoride-tetrafluoroethylene copolymer, vinylidene cyanide-vinyl acetate copolymer, cyanoethylcellulose, cyanoethylhydroxysaccharose, cyanoethylhydroxycellulose, cyanoethylhydroxypullulan, cyanoethylmethacrylate, cyanoethylacrylate, cyanoethyl Cyano groups such as hydroxyethylcellulose, cyanoethylamylose, cyanoethylhydroxypropylcellulose, cyanoethyldihydroxypropylcellulose, cyanoethylhydroxypropylamylose, cyanoethylpolyacrylamide, cyanoethylpolyacrylate, cyanoethylpullulan, cyanoethylpolyhydroxymethylene, cyanoethylglycidolpullul
  • polymers having cyanoethyl groups and synthetic rubbers such as nitrile rubbers and chloroprene rubbers are exemplified.
  • polymer materials having cyanoethyl groups are preferably used.
  • these dielectric polymer materials are not limited to one type, and a plurality of types may be added.
  • thermoplastic resins such as vinyl chloride resins, polyethylene, polystyrene, methacrylic resins, polybutene and isobutylene, and phenolic resins are used for the purpose of adjusting the glass transition point Tg of the polymer matrix 38.
  • thermosetting resins such as urea resins, melamine resins, alkyd resins and mica may be added.
  • a tackifier such as rosin ester, rosin, terpene, terpene phenol, and petroleum resin may be added for the purpose of improving adhesiveness.
  • the addition amount of the polymer material other than the polymer material having viscoelasticity at room temperature is not limited, but the proportion of the polymer matrix 38 is 30% by mass. It is preferable to: As a result, the characteristics of the polymer material to be added can be expressed without impairing the viscoelastic relaxation mechanism in the polymer matrix 38, so that the dielectric constant can be increased, the heat resistance can be improved, and the adhesion with the piezoelectric particles 40 and the electrode layer can be improved. Favorable results can be obtained in terms of improvement and the like.
  • the polymer composite piezoelectric material that forms the piezoelectric layer 26 contains piezoelectric particles 40 in such a polymer matrix.
  • the piezoelectric particles 40 are dispersed in a polymer matrix, preferably uniformly (substantially uniformly).
  • the piezoelectric particles 40 are preferably ceramic particles having a perovskite or wurtzite crystal structure. Examples of ceramic particles constituting the piezoelectric particles 40 include lead zirconate titanate (PZT), lead zirconate lanthanate titanate (PLZT), barium titanate (BaTiO 3 ), zinc oxide (ZnO), and A solid solution (BFBT) of barium titanate and bismuth ferrite (BiFe 3 ) is exemplified.
  • the particle size of the piezoelectric particles 40 may be appropriately selected according to the size and application of the piezoelectric film 12 .
  • the particle size of the piezoelectric particles 40 is preferably 1 to 10 ⁇ m.
  • the quantitative ratio of the polymer matrix 38 and the piezoelectric particles 40 in the piezoelectric layer 26 is required for the size and thickness of the piezoelectric film 12 in the plane direction, the application of the piezoelectric film 12, and the piezoelectric film 12. It may be set as appropriate according to the characteristics of the device.
  • the volume fraction of the piezoelectric particles 40 in the piezoelectric layer 26 is preferably 30-80%, more preferably 50-80%.
  • the thickness of the piezoelectric layer 26 is not limited, and can be appropriately set according to the size of the piezoelectric film 12, the application of the piezoelectric film 12, the properties required of the piezoelectric film 12, and the like. good.
  • the thickness of the piezoelectric layer 26 is preferably 8-300 ⁇ m, more preferably 8-200 ⁇ m, still more preferably 10-150 ⁇ m, particularly preferably 15-100 ⁇ m.
  • the piezoelectric layer 26 is preferably polarized (poled) in the thickness direction.
  • the polarization treatment will be detailed later.
  • the piezoelectric layer 26 is a polymer composite containing piezoelectric particles 40 in a polymer matrix 38 made of a polymer material having viscoelasticity at room temperature, such as cyanoethylated PVA, as described above.
  • a polymer material having viscoelasticity at room temperature such as cyanoethylated PVA
  • piezoelectric bodies there is no limitation to piezoelectric bodies. That is, in the piezoelectric film 12, various known piezoelectric layers can be used for the piezoelectric layer.
  • a high-performance dielectric material containing similar piezoelectric particles 40 in a matrix containing a dielectric polymer material such as the polyvinylidene fluoride, vinylidene fluoride-tetrafluoroethylene copolymer, and vinylidene fluoride-trifluoroethylene copolymer described above may be used.
  • Molecular composite piezoelectric material, piezoelectric layer made of polyvinylidene fluoride, piezoelectric layer made of fluorine resin other than polyvinylidene fluoride, and piezoelectric layer made by laminating a film made of poly-L-lactic acid and a film made of poly-D-lactic acid, etc. is also available.
  • the piezoelectric film 12 shown in FIG. 4 has the second electrode layer 30 on one surface of the piezoelectric layer 26, the second protective layer 34 on the surface of the second electrode layer 30, and the piezoelectric layer 26 has a first electrode layer 28 on the other surface thereof, and has a first protective layer 32 on the surface of the first electrode layer 28 .
  • the first electrode layer 28 and the second electrode layer 30 form an electrode pair.
  • both surfaces of the piezoelectric layer 26 are sandwiched between electrode pairs, that is, the first electrode layer 28 and the second electrode layer 30, and the first protective layer 32 and the second electrode layer 30 are sandwiched between the electrode pairs. It has a configuration sandwiched between protective layers 34 .
  • the regions sandwiched by the first electrode layer 28 and the second electrode layer 30 are driven according to the applied voltage.
  • the piezoelectric film 12 includes, for example, an adhesive layer for attaching the electrode layer and the piezoelectric layer 26 and an adhesive layer for attaching the electrode layer and the protective layer. may have.
  • the adhesive may be an adhesive or an adhesive.
  • a polymer material obtained by removing the piezoelectric particles 40 from the piezoelectric layer 26, ie, the same material as the polymer matrix 38, can be suitably used.
  • the adhesive layer may be provided on both the first electrode layer 28 side and the second electrode layer 30 side, or may be provided on only one of the first electrode layer 28 side and the second electrode layer 30 side. good.
  • the first protective layer 32 and the second protective layer 34 cover the first electrode layer 28 and the second electrode layer 30, and provide the piezoelectric layer 26 with appropriate rigidity and mechanical strength. is responsible for That is, in the piezoelectric film 12, the piezoelectric layer 26 containing the polymer matrix 38 and the piezoelectric particles 40 exhibits excellent flexibility against slow bending deformation, but depending on the application, the piezoelectric layer 26 exhibits excellent flexibility. , rigidity and mechanical strength may be insufficient.
  • the piezoelectric film 12 is provided with a first protective layer 32 and a second protective layer 34 to compensate.
  • the first protective layer 32 and the second protective layer 34 have the same configuration, except for the arrangement position. Therefore, in the following description, when there is no need to distinguish between the first protective layer 32 and the second protective layer 34, both members are collectively referred to as protective layers.
  • the protective layer there are no restrictions on the protective layer, and various sheet-like materials can be used, and various resin films are suitable examples. Among them, polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), polycarbonate (PC), polyphenylene sulfite (PPS), polymethyl methacrylate (PMMA), due to their excellent mechanical properties and heat resistance. ), polyetherimide (PEI), polyimide (PI), polyamide (PA), polyethylene naphthalate (PEN), triacetyl cellulose (TAC), and resin films made of cyclic olefin resins are preferably used. .
  • the thickness of the protective layer is also not limited. Also, the thicknesses of the first protective layer 32 and the second protective layer 34 are basically the same, but may be different. If the rigidity of the protective layer is too high, it not only restricts expansion and contraction of the piezoelectric layer 26, but also impairs its flexibility. Therefore, the thinner the protective layer, the better, except when mechanical strength and good handling properties as a sheet are required.
  • the thickness of each of the first protective layer 32 and the second protective layer 34 is not more than twice the thickness of the piezoelectric layer 26, favorable results can be achieved in terms of ensuring both rigidity and appropriate flexibility. is obtained.
  • the thickness of the piezoelectric layer 26 is 50 ⁇ m and the first protective layer 32 and the second protective layer 34 are made of PET, the thicknesses of the first protective layer 32 and the second protective layer 34 are each preferably 100 ⁇ m or less. , 50 ⁇ m or less, and even more preferably 25 ⁇ m or less.
  • the piezoelectric film 12 may have only the first protective layer 32, only the second protective layer 34, or no protective layer.
  • the piezoelectric film preferably has at least one protective layer. More preferably, it has two protective layers.
  • a first electrode layer 28 is provided between the piezoelectric layer 26 and the first protective layer 32, and a second electrode layer 30 is provided between the piezoelectric layer 26 and the second protective layer 34. be provided.
  • the first electrode layer 28 and the second electrode layer 30 are for applying voltage to the piezoelectric layer 26 .
  • the application of voltage from the electrode layer to the piezoelectric layer 26 causes the piezoelectric film 12 to expand and contract.
  • the first electrode layer 28 and the second electrode layer 30 are basically the same except for their positions. Therefore, in the following description, when there is no need to distinguish between the first electrode layer 28 and the second electrode layer 30, both members are collectively referred to as electrode layers.
  • the material for forming the electrode layer is not limited, and various conductors can be used. Specifically, carbon, palladium, iron, tin, aluminum, nickel, platinum, gold, silver, copper, chromium, molybdenum, alloys thereof, indium tin oxide, and PEDOT/PPS (polyethylenedioxythiophene-polystyrenesulfone acid) and other conductive polymers are exemplified. Among them, copper, aluminum, gold, silver, platinum, and indium tin oxide are preferred. Among them, copper is more preferable from the viewpoint of conductivity, cost, flexibility, and the like.
  • the method of forming the electrode layer is not limited, and a vapor phase deposition method (vacuum film formation method) such as vacuum deposition and sputtering, a method of forming a film by plating, a method of attaching a foil formed of the above materials, a coating method, or the like.
  • a vapor phase deposition method vacuum film formation method
  • a method of forming a film by plating a method of attaching a foil formed of the above materials, a coating method, or the like.
  • a thin film of copper or aluminum formed by vacuum deposition is preferably used as the electrode layer because the flexibility of the piezoelectric film 12 can be ensured.
  • a copper thin film formed by vacuum deposition is particularly preferably used.
  • the thicknesses of the first electrode layer 28 and the second electrode layer 30 are not limited. Also, the thicknesses of the first electrode layer 28 and the second electrode layer 30 are basically the same, but may be different.
  • the protective layer described above if the rigidity of the electrode layer is too high, not only will the expansion and contraction of the piezoelectric layer 26 be restricted, but also the flexibility will be impaired. Therefore, the thinner the electrode layer, the better, as long as the electrical resistance does not become too high.
  • the first protective layer 32 and the second protective layer 34 are made of PET, and the first electrode layer 28 and the second electrode layer 30 are made of copper.
  • the Young's modulus of PET is about 6.2 GPa and the Young's modulus of copper is about 130 GPa. Therefore, if the thickness of the protective layer is 25 ⁇ m, the thickness of the electrode layer is preferably 1.2 ⁇ m or less, more preferably 0.3 ⁇ m or less, and most preferably 0.1 ⁇ m or less.
  • the piezoelectric film 12 has a structure in which a piezoelectric layer 26 is sandwiched between a first electrode layer 28 and a second electrode layer 30, and this laminated body is sandwiched between a first protective layer 32 and a second protective layer .
  • the loss tangent (Tan[delta]) at a frequency of 1 Hz by dynamic viscoelasticity measurement has a maximum value of 0.1 or more at room temperature.
  • the piezoelectric film 12 preferably has a storage elastic modulus (E') at a frequency of 1 Hz measured by dynamic viscoelasticity measurement of 10 to 30 GPa at 0°C and 1 to 10 GPa at 50°C. Accordingly, the piezoelectric film 12 can have a large frequency dispersion in the storage elastic modulus (E') at room temperature. That is, it can act hard against vibrations of 20 Hz to 20 kHz and soft against vibrations of several Hz or less.
  • E' storage elastic modulus
  • the piezoelectric film 12 has a product of thickness and storage elastic modulus (E′) at a frequency of 1 Hz determined by dynamic viscoelasticity measurement of 1.0 ⁇ 10 6 to 2.0 ⁇ 10 6 N/m at 0° C. , 1.0 ⁇ 10 5 to 1.0 ⁇ 10 6 N/m at 50°C.
  • E′ thickness and storage elastic modulus
  • the piezoelectric film 12 preferably has a loss tangent (Tan ⁇ ) of 0.05 or more at 25°C and a frequency of 1 kHz in a master curve obtained from dynamic viscoelasticity measurement.
  • FIG. 5 a sheet 42b conceptually shown in FIG. 5 is prepared in which the second electrode layer 30 is formed on the surface of the second protective layer 34 . Further, a sheet-like material 42a conceptually shown in FIG. 7 is prepared, in which the first electrode layer 28 is formed on the surface of the first protective layer 32. Next, as shown in FIG.
  • the sheet-like material 42b may be produced by forming a copper thin film or the like as the second electrode layer 30 on the surface of the second protective layer 34 by vacuum deposition, sputtering, plating, or the like.
  • the sheet 42a may be produced by forming a copper thin film or the like as the first electrode layer 28 on the surface of the first protective layer 32 by vacuum deposition, sputtering, plating, or the like.
  • a commercially available sheet having a copper thin film or the like formed on a protective layer may be used as the sheet 42b and/or the sheet 42a.
  • the sheet 42b and the sheet 42a may be the same or different.
  • a protective layer with a separator temporary support
  • PET or the like having a thickness of 25 to 100 ⁇ m can be used as the separator.
  • the separator may be removed after the electrode layer and protective layer are thermocompression bonded.
  • the piezoelectric layer 26 is formed on the second electrode layer 30 of the sheet 42b, and the laminate 46 obtained by laminating the sheet 42b and the piezoelectric layer 26 is obtained. to make.
  • the piezoelectric layer 26 may be formed by a known method suitable for the piezoelectric layer 26 .
  • a piezoelectric layer (polymer composite piezoelectric layer) in which piezoelectric particles 40 are dispersed in a polymer matrix 38 shown in FIG. 4 is manufactured as follows. First, a polymer material such as cyanoethylated PVA is dissolved in an organic solvent, and piezoelectric particles 40 such as PZT particles are added and stirred to prepare a paint.
  • Organic solvents are not limited, and various organic solvents such as dimethylformamide (DMF), methyl ethyl ketone, and cyclohexanone can be used.
  • the coating material there are no restrictions on the method of casting the coating material, and known methods (coating equipment) such as bar coaters, slide coaters and doctor knives can all be used.
  • coating equipment such as bar coaters, slide coaters and doctor knives can all be used.
  • the polymer material is heat-meltable, the polymer material is heat-melted and the piezoelectric particles 40 are added to prepare a melt, which is then extruded into a sheet shown in FIG.
  • a laminate 46 as shown in FIG. 6 may be produced by extruding a sheet onto the shaped material 42b and cooling.
  • the polymer matrix 38 may be added with a polymer piezoelectric material such as PVDF in addition to the polymer material having viscoelasticity at room temperature.
  • a polymer piezoelectric material such as PVDF
  • the polymeric piezoelectric materials to be added to the paint may be dissolved.
  • the polymer piezoelectric material to be added may be added to a polymer material that has been melted by heating and has viscoelasticity at room temperature, and then melted by heating.
  • the piezoelectric layer 26 After the piezoelectric layer 26 is formed, it may be calendered, if desired. Calendering may be performed once or multiple times. As is well known, calendering is a process in which a surface to be treated is heated and pressed by a heating press, a heating roller, a pair of heating rollers, or the like to flatten the surface.
  • the piezoelectric layer 26 of the laminate 46 having the second electrode layer 30 on the second protective layer 34 and the piezoelectric layer 26 formed on the second electrode layer 30 is subjected to polarization treatment (poling). )I do.
  • the method of polarization treatment of the piezoelectric layer 26 is not limited, and known methods can be used.
  • electric field poling in which a DC electric field is directly applied to an object to be polarized, is exemplified.
  • the first electrode layer 28 may be formed before the polarization treatment, and the electric field poling treatment may be performed using the first electrode layer 28 and the second electrode layer 30.
  • the previously prepared sheet 42a is laminated on the piezoelectric layer 26 side of the laminated body 46 with the first electrode layer 28 facing the piezoelectric layer 26.
  • this laminate is thermocompression bonded by using a hot press device, a heating roller, etc., with the first protective layer 32 and the second protective layer 34 sandwiched between them, thereby joining the laminate 46 and the sheet-like material 42a. to paste together.
  • the piezoelectric layer 26, the first electrode layer 28 and the second electrode layer 30 provided on both surfaces of the piezoelectric layer 26, and the first protective layer 32 and the second protective layer 34 formed on the surface of the electrode layer
  • the piezoelectric film 12 produced in this manner is polarized in the thickness direction rather than in the surface direction, and excellent piezoelectric properties can be obtained without stretching after the polarization treatment. Therefore, the piezoelectric film 12 has no in-plane anisotropy in piezoelectric properties, and expands and contracts isotropically in all directions in the plane direction when a drive voltage is applied.
  • the piezoelectric element 10 is formed by laminating a plurality of layers by folding the piezoelectric film 12 and adhering the laminated and adjacent piezoelectric films 12 to each other with the adhesive layer 20 .
  • the piezoelectric element 10 of the present invention as shown in FIG. is L, "L ⁇ 50*t" is satisfied.
  • the ridgeline is a folding line formed by the apex of the folding end (outer end) of the piezoelectric film 12 .
  • the thickness of the piezoelectric element 10 is the thickness of the piezoelectric film 12 in the stacking direction.
  • the thickest portion M of the piezoelectric element 10 is the thickest portion in the stacking direction of the piezoelectric film 12 . Further, as will be described later, in the present invention, the thickest portion M of the piezoelectric element 10 is the thickest portion of the piezoelectric element 10 in the folding direction of the piezoelectric film 12 .
  • the piezoelectric element 10 of the present invention has such a configuration, when the piezoelectric element 10 is pressed, such as when the piezoelectric element 10 is attached to a diaphragm, the piezoelectric element 10 is bent at the folded portion of the piezoelectric film 12 . Damage to the layer 26 and the electrode layer can be prevented. As a result, when the piezoelectric element 10 of the present invention is used as an exciter in a piezoelectric speaker, for example, it can properly perform a set operation and properly output sound at a target sound pressure.
  • a piezoelectric element laminated piezoelectric element in which the piezoelectric film 12 is folded and laminated is used as, for example, an exciter that vibrates a diaphragm to output sound.
  • a piezoelectric speaker is manufactured using a piezoelectric element as an exciter, it is necessary to adhere the piezoelectric element 10 to the diaphragm 62 as conceptually shown in FIG. 12, which will be described later.
  • the piezoelectric element and the vibration plate are attached by pressing the piezoelectric element against the vibration plate with an adhesive such as an adhesive. Moreover, this pressing is performed while heating the adhesive material, that is, the piezoelectric element and/or the diaphragm, as necessary.
  • the piezoelectric film 12 using a polymer composite piezoelectric material for the piezoelectric layer 26 has good flexibility. Therefore, the piezoelectric element in which this piezoelectric film 12 is laminated also has good flexibility. Therefore, in this case, by using a windable diaphragm and attaching a piezoelectric element as an exciter to the diaphragm, a windable piezoelectric speaker can be realized. However, in this piezoelectric speaker, when the diaphragm is wound, the piezoelectric film is similarly subjected to surface pressure. end up
  • the piezoelectric element 10 of the present invention is a (laminated) piezoelectric element in which the piezoelectric film 12 is laminated by folding back, wherein the thickness of the adhesive layer 20 at the thickest portion M of the piezoelectric element 10 is t, and the thickness of the piezoelectric element 10 is When the shortest distance between the thickest portion M of 10 and the edge of the folded portion, that is, the ridgeline is L, "L ⁇ 50*t" is satisfied. That is, in the piezoelectric element 10 of the present invention, the shortest distance between the thickest portion M and the ridgeline is 20 times or more the thickness t of the adhesive layer 20 at the thickest portion M, which is sufficiently far.
  • the highest pressure is applied to the piezoelectric element 10 at the thickest portion M, and the piezoelectric film 12 at the thickest portion M is subjected to the highest pressure. Face pressure is applied.
  • the thickest portion M of the piezoelectric element 10 is subjected to the highest pressure, and the piezoelectric film 12 at the thickest portion M is subjected to the highest surface pressure.
  • the shortest distance L between the thickest portion M and the ridgeline is 20 times or more the thickness t of the adhesive layer 20 at the thickest portion. That is, in the piezoelectric element 10 of the present invention, the thickest portion M is provided on the inner side of the folded portion in the folding direction, and the thickest portion M where the piezoelectric film 12 receives the highest surface pressure and the piezoelectric layer 26 and the like are provided. The folded portion of the piezoelectric film 12, which is likely to break, is sufficiently separated.
  • the thickest portion M of the piezoelectric film 12 receives the highest surface pressure, and a high surface pressure is applied to the piezoelectric film 12 at the bent portion sufficiently distant from the thickest portion M. can be prevented.
  • the piezoelectric element 10 of the present invention can prevent breakage of the piezoelectric layer 26 and/or the electrode layer at the bent portion when the diaphragm is pressed.
  • the thickest portion M is substantially flat, even if a high surface pressure is applied, the piezoelectric layer 26 and the electrode layer will not break.
  • the piezoelectric element 10 of the present invention can properly perform a predetermined operation even after being pressed by being attached to the diaphragm or the like.
  • a piezoelectric speaker using the piezoelectric element 10 of the present invention as an exciter can properly output sound at a set sound pressure.
  • the shortest distance L between the thickest portion M of the piezoelectric element 10 and the ridge line, that is, the edge of the bent portion is the shortest distance in the planar shape of the piezoelectric element 10 . That is, the shortest distance L between the thickest portion M of the piezoelectric element 10 and the ridge line is the shortest distance when the piezoelectric element 10 is viewed from above.
  • the thickest portion M of the piezoelectric element 10 is the thickest position of the piezoelectric element 10 in the folding direction of the piezoelectric film 12, that is, the horizontal direction in FIG.
  • a piezoelectric element in which three or more layers of piezoelectric films 12 are laminated has folding portions at both ends in the folding direction.
  • the folded portion closer to the thickest portion M becomes the target of the shortest distance L.
  • the piezoelectric films 12 are folded and laminated such that the positions of the ridgelines of the piezoelectric films 12 are aligned in the folding direction, that is, in the planar shape.
  • the positions of the ridge lines may differ in the folding direction at each folded portion.
  • the distance L1 between the shortest ridgeline and the thickest portion M in the plan view is not the distance L2 between the farthest ridgeline and the thickest portion M in plan view.
  • the shortest distance L between the thickest portion M and the ridgeline (turned end portion) in the piezoelectric element 10 .
  • FIG. 1 shows the thickness t of the thickest portion M of the adhesive layer 20 as the uppermost layer
  • the piezoelectric film 12 having three or more layers can be formed by folding one piezoelectric film two or more times.
  • a plurality of adhesion layers 20 are present.
  • the thickness t of the adhesive layer 20 at the thickest portion M of the piezoelectric element 10 is the average thickness of the adhesive layer 20 at the thickest portion M.
  • FIG. For example, in the case of FIG. Let be t.
  • a method for determining the thickest portion M of the piezoelectric element 10 of the present invention and a method for determining the thickness t of the adhesive layer 20 at the thickest portion M will be described in detail later. Further, in the following description, the shortest distance L between the edge of the folded portion of the piezoelectric film 12, that is, the ridge line, and the thickest portion M of the piezoelectric element 10 is also simply referred to as "shortest distance L”. Further, the thickness t of the adhesive layer 20 at the thickest portion M is also simply referred to as "the thickness t of the adhesive layer”.
  • the shortest distance L and the thickness t of the adhesive layer satisfy "L ⁇ 50*t". If the shortest distance L is less than "50*t", the folded portion and the thickest portion M of the piezoelectric film 12 are too close, and the piezoelectric film 12 at the folded portion is subjected to a surface pressure equivalent to that of the thickest portion M, which has the highest surface pressure. It takes. As a result, breakage of the piezoelectric layer 26 and the electrode layer at the folded portion cannot be sufficiently prevented.
  • the effect of the present invention can be preferably obtained as the thickest portion M of the piezoelectric element 10 is separated from the ridge line of the piezoelectric film 12 .
  • the shortest distance L preferably satisfies "L ⁇ 60*t".
  • the upper limit of the shortest distance L is half the length of the piezoelectric film 12 in the planar shape of the piezoelectric element 10 in the folding direction.
  • the direction of the folding line at the end of the folding portion of the piezoelectric film 12, that is, the direction of the ridgeline of the piezoelectric film 12 at the folding portion is defined as the x direction.
  • the direction orthogonal to the x direction, which is the direction of the ridge line, that is, the folding direction of the piezoelectric film 12 in the piezoelectric element 10 is defined as the y direction.
  • the shortest distance L, the thickest portion, and the thickness t of the adhesive layer of the piezoelectric element 10 are defined by the center line, which is the center line in the x direction, as conceptually shown in the lower plan view of FIG. measurement line x1, the x-direction length of the piezoelectric element 10, i.e., the y-direction measurement lines x2 and x3 located inward from the ends in the x-direction by 5% of the length of the ridge, and With five lines, a y-direction measurement line x4 located between the center measurement line x1 and the measurement line x2, and a y-direction measurement line x5 located between the center measurement line x1 and the measurement line x3 Take measurements and decide.
  • the shortest distance L and the thickest portion M of the piezoelectric element 10 are determined as follows. First, the highest point, which is the highest position of the piezoelectric element 10, is detected on the central measurement line x1 of the piezoelectric element 10 and all the measurement lines x2 to x5. Next, for each measurement line, the shortest distance between the highest point and the ridge line in the planar shape is measured. If the positions of the ridgelines are different in the y direction at each folded portion, the shortest distance is the shortest distance to the ridgeline closest to the highest point, as in FIG. 8 described above. Next, the average value of the shortest distances between the highest point of each measured line and the ridge is calculated.
  • This average value is taken as the shortest distance L between the thickest portion M and the ridge line, that is, the edge of the folded portion in the piezoelectric element 10 .
  • the entire area in the x direction at the position of the shortest distance L in the y direction from the target ridgeline is defined as the thickest portion M of the piezoelectric element 10 . That is, in the piezoelectric element 10 of the present invention, the thickest portion M is the position in the x direction, that is, the ridgeline direction, where the piezoelectric element 10 is thickest in the y direction, that is, the folding direction of the piezoelectric film 12 .
  • the position of the highest point of the piezoelectric element 10 may be detected by measuring the surface shape of the piezoelectric element 10 using, for example, a contour shape measuring instrument.
  • a contour measuring instrument for example, CV-3000 manufactured by Mitutoyo Corporation is exemplified.
  • the thickness of the thickest portion M (thickness T1, which will be described later) of the piezoelectric element 10 is measured by a digimatic indicator using a flat-type probe with a diameter of 2 mm.
  • the thickness of the thickest portion M is also measured along the central measurement line x1 of the piezoelectric element 10 and all of the measurement lines x2 to x5, and the average value is taken as the thickness of the thickest portion M in the piezoelectric element 10. .
  • Digimatic indicator is ID-S112X manufactured by Mitutoyo Corporation.
  • thickness T2 which will be described later
  • the thickness of the piezoelectric element 10 is also the same.
  • the thickness t of the adhesive layer at the thickest portion M is determined as follows. First, the thickness of the adhesive layer 20 at the determined thickest portion M is measured along the center measurement line x1 of the piezoelectric element 10 and all of the measurement lines x2 to x5. The thickness of the adhesive layer 20 at the thickest portion M at each measurement line is determined by observing the thickest portion M with a SEM (Scanning Electron Microscope) in the cross section at each measurement line. It may be measured by a known method using an SEM image. Thickness measurement is performed at the thickest portion M of all the adhesive layers 20 . Since the piezoelectric element 10 shown in FIG.
  • the thickness of the thickest portion M is not limited.
  • the thickness T1 is equal to the thickness T2. of 115% or more.
  • the thickness of the piezoelectric element 10 at the folded portion of the piezoelectric film 12 is also referred to as the "thickness of the folded portion" for convenience.
  • the thickness T1 of the thickest portion is preferably 1.15 times or more the thickness T2 of the folded portion.
  • the piezoelectric layer 26 and/or the electrode layer can more preferably be prevented from breaking at the folded portion when pressed against the diaphragm and when wound together with the diaphragm.
  • ESR Equivalent Series Resistance
  • the thickness T1 of the thickest portion is more preferably 116% or more, more preferably 117% or more, of the thickness T2 of the folded portion.
  • the thickness T1 of the thickest portion is preferably 130% or less of the thickness T2 of the folded portion. If the thickness T1 of the thickest portion is too thick with respect to the thickness T2 of the folded portion, it becomes difficult to attach the piezoelectric element 10 to a vibration plate or the like, the expansion and contraction of the piezoelectric element 10 in the planar direction becomes unstable, and the winding becomes unstable. In the case of using a removable diaphragm, there is a possibility that problems such as unevenness (occurrence of reflection) may occur on the diaphragm when it is wound. On the other hand, by setting the thickness T1 of the thickest portion within the range described above, it is possible to preferably avoid the occurrence of these problems.
  • the thickness of the folded portion is a flat type of ⁇ 2 mm so as to include a portion up to 1 mm inward in the folded direction from the bent portion end of the uppermost folded portion (end in the stacking direction) of the piezoelectric element 10 .
  • the thickness of the piezoelectric element 10 is measured by a digimatic indicator using a probe, and the thickest thickness is defined as the thickness T2 of the folded portion of the piezoelectric element 10 .
  • the thickness T1 of the thickest portion and the thickness T2 of the folded portion are both the maximum thickness at the center measurement line x1 and the measurement lines x2 to x5 of the piezoelectric element 10 shown in FIG.
  • the thicknesses of the portions and the folded portions are measured, and the average values are used as the thickness T1 of the thickest portion and the thickness T2 of the folded portions in the piezoelectric element 10 .
  • the piezoelectric element 10 is formed by folding and laminating the piezoelectric films 12 and adhering the adjacent piezoelectric films 12 by lamination with the adhesive layer 20 .
  • an adhesive layer 20 is provided near one end of the piezoelectric film 12, and then, as shown in the third row, the piezoelectric film 12 is folded and laminated. . 1st stage, 2nd stage, . . . indicate the number of stages from the top in the figure.
  • the folded and laminated piezoelectric film 12 is pressed by moving a roller 50 capable of pressing the entire area in the direction of the ridge line in the folding direction, and the laminated two-layered piezoelectric film 12 is adhered.
  • a pair of rollers may be used for the rollers 50 .
  • a heating roller may be used as the roller 50 to adhere the piezoelectric film 12 while heating.
  • the adhesive layer 20 is provided on the laminated piezoelectric film 12, and as shown in the sixth row, the piezoelectric film 12 is folded again and laminated.
  • the laminated piezoelectric film 12 is adhered by moving the roller 50 capable of pressing the entire ridgeline direction in the folding direction.
  • a piezoelectric element having a desired number of layers of the piezoelectric film 12 can be manufactured.
  • the thickness of the piezoelectric film 12 is basically uniform (substantially uniform) over the entire surface. Therefore, the thickness of the piezoelectric element and the position and thickness of the thickest portion M are controlled by the thickness of the adhesive layer 20 .
  • the pressing force of the roller 50 for adhering the laminated piezoelectric film 12 is partially adjusted in the moving direction of the roller 50 . That is, by weakening the pressing force of the roller 50, the thickness of the adhesive layer 20 at that position can be increased, and as a result, the thickness of the piezoelectric element can be increased.
  • the thickest portion M can be provided at an arbitrary position in the folding direction (the y direction in FIG. 9) of the piezoelectric film 12 .
  • the pressing force of the rollers 50 may be changed for all the adhesive layers 20, or the adhesive layers 20 whose pressing force is not changed may be One layer or multiple layers may be set.
  • the piezoelectric element 10 of the present invention expands and contracts the piezoelectric layer 26 by applying a driving voltage to the first electrode layer 28 and the second electrode layer 30 .
  • a driving voltage For this purpose, it is necessary to electrically connect the first electrode layer 28 and the second electrode layer 30 to an external device such as an external power source.
  • an external device such as an external power source.
  • Various known methods can be used to connect the first electrode layer 28 and the second electrode layer 30 to an external device.
  • the piezoelectric film 12 is extended at one end to provide a protruding portion 12a protruding from the area where the piezoelectric film 12 is laminated.
  • a method of providing a lead wiring for electrical connection with an external device to the projecting portion 12a is exemplified.
  • the protruding portion specifically indicates a single-layer region that does not overlap with other piezoelectric films 12 when viewed in a planar shape, that is, in the stacking direction.
  • the thickest part of the piezoelectric element 10 is omitted.
  • the projecting portion 12a of the piezoelectric element 10 is connected to a first lead wire 72 and a second lead wire 74 for electrically connecting to an external device such as a power supply.
  • the first lead wire 72 is a wire electrically led out from the first electrode layer 28
  • the second lead wire 74 is a wire electrically led out from the second electrode layer 30 .
  • lead wire when there is no need to distinguish between the first lead wire 72 and the second lead wire 74, they will simply be referred to as lead wire.
  • the method of connecting the electrode layer and the lead wire ie, the lead method
  • the lead method is not limited, and various methods can be used.
  • a method of forming a through hole in the protective layer, providing an electrode connection member formed of a metal paste such as silver paste so as to fill the through hole, and providing a lead wire in the electrode connection member is exemplified.
  • a rod-shaped or sheet-shaped lead electrode is provided between the electrode layer and the piezoelectric layer or between the electrode layer and the protective layer, and the lead wire is connected to the lead electrode. A method is illustrated.
  • the lead wiring may be directly inserted between the electrode layer and the piezoelectric layer or between the electrode layer and the protective layer to connect the lead wiring to the electrode layer.
  • a method is exemplified in which a part of the protective layer and the electrode layer protrudes from the piezoelectric layer in the plane direction, and the protruding electrode layer is connected to the lead wiring.
  • the lead wiring and the electrode layer may be connected by a known method such as a method using a metal paste such as silver paste, a method using solder, or a method using a conductive adhesive. Examples of suitable methods for extracting electrodes include the method described in Japanese Patent Application Laid-Open No. 2014-209724 and the method described in Japanese Patent Application Laid-Open No. 2016-015354.
  • a projecting part such as a dejima projecting from the piezoelectric film may be provided, and a lead wire for connecting an external device may be provided here.
  • a plurality of these protrusions may be used together as required.
  • the piezoelectric element 10 of the present invention can be used for various purposes as described later. Among others, the piezoelectric element 10 of the present invention is preferably used as an exciter that outputs sound by vibrating a diaphragm.
  • FIG. 12 conceptually shows an example of the piezoelectric speaker of the present invention.
  • the piezoelectric speaker of the present invention is used as an exciter by attaching the piezoelectric element 10 of the present invention to a diaphragm and vibrating the diaphragm to output sound.
  • the piezoelectric speaker 60 has a piezoelectric element 10 attached to a diaphragm 62 with an adhesive layer 68 .
  • the number of piezoelectric elements attached to one diaphragm 62 is not limited to one. good too. Further, for example, by providing two piezoelectric elements 10 on one diaphragm 62 and applying different drive voltages to each piezoelectric element 10, one diaphragm 62 can output, for example, stereo sound. good too.
  • the diaphragm 62 is not limited, and various sheet-like materials can be used as long as they act as a diaphragm that outputs sound by vibration of the exciter.
  • the diaphragm 62 may be, for example, polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), polycarbonate (PC), polyphenylene sulfite (PPS), polymethyl methacrylate (PMMA). ), polyetherimide (PEI), polyimide (PI), polyethylene naphthalate (PEN), triacetyl cellulose (TAC), resin films made of cyclic olefin resins, foamed polystyrene, foamed styrene, foamed polyethylene, etc.
  • PET polyethylene terephthalate
  • PP polypropylene
  • PS polystyrene
  • PC polycarbonate
  • PPS polyphenylene sulfite
  • PMMA polymethyl methacrylate
  • PEI polyetherimide
  • PI polyimide
  • PEN polyethylene naphthalate
  • TAC triacetyl cellulose
  • the piezoelectric speaker 60 of the present invention uses, as the diaphragm 62, an organic electroluminescence (OLED (Organic Light Emitting Diode) display, a liquid crystal display, a micro LED (Light Emitting Diode) display, an inorganic electroluminescence display, or the like.
  • OLED Organic Light Emitting Diode
  • a liquid crystal display a micro LED (Light Emitting Diode) display
  • an inorganic electroluminescence display or the like.
  • Various display devices and the like can also be suitably used.
  • the piezoelectric speaker 60 of the present invention can suitably use, as the diaphragm 62, electronic devices such as smart phones, mobile phones, tablet terminals, personal computers such as notebook computers, and wearable devices such as smart watches.
  • the piezoelectric speaker of the present invention can suitably use various metals such as stainless steel, aluminum, copper and nickel, and thin film metals made of various alloys as the diaphragm 62 .
  • the diaphragm 62 may be flexible, including the case where the diaphragm 62 is a display device, an electronic device, or the like.
  • the piezoelectric film 12 has good flexibility. Therefore, the laminated piezoelectric element 10 of the present invention in which the piezoelectric films 12 are laminated also has good flexibility. Therefore, by using the diaphragm 62 having flexibility, it is possible to realize a piezoelectric speaker that can be bent, bent, folded, and wound.
  • the bonding layer 68 that bonds the diaphragm 62 and the piezoelectric element 10 is not limited as long as it can bond the diaphragm 62 and the piezoelectric element 10 (piezoelectric film 12).
  • various adhesives are available.
  • the bonding layer 68 for bonding the diaphragm 62 and the piezoelectric element 10 may be the same as the bonding layer 20 for bonding the adjacent piezoelectric film 12 described above. It is possible. Also, the preferred adhesive layer 68 is the same.
  • the thickness of the adhesive layer 68 is not limited, and a thickness capable of exhibiting sufficient adhesive force may be appropriately set according to the material forming the adhesive layer 68 .
  • the thinner the adhesive layer 68 is the higher the effect of transmitting the expansion/contraction energy (vibration energy) of the piezoelectric film 12 can be and the higher the energy efficiency can be.
  • the adhesive layer is thick and rigid, it may restrict expansion and contraction of the piezoelectric element 10 .
  • the thickness of the adhesive layer 68 that attaches the vibration plate 62 and the piezoelectric element 10 is preferably 10 to 1000 ⁇ m, more preferably 30 to 500 ⁇ m, more preferably 50 to 300 ⁇ m. is more preferred.
  • the piezoelectric film 12 has the piezoelectric layer 26 sandwiched between the first electrode layer 28 and the second electrode layer 30 .
  • piezoelectric layer 26 comprises piezoelectric particles 40 dispersed in polymer matrix 38 .
  • the piezoelectric particles 40 expand and contract in the polarization direction according to the applied voltage.
  • the piezoelectric film 12 shrinks in the thickness direction.
  • the piezoelectric film 12 expands and contracts in the plane direction as well. This expansion and contraction is about 0.01 to 0.1%.
  • the thickness of the piezoelectric layer 26 is preferably about 8-300 ⁇ m. Therefore, the expansion and contraction in the thickness direction is as small as about 0.3 ⁇ m at maximum.
  • the piezoelectric film 12 that is, the piezoelectric layer 26, has a size much larger than its thickness in the planar direction. Therefore, for example, if the length of the piezoelectric film 12 is 20 cm, the piezoelectric film 12 expands and contracts by about 0.2 mm at maximum due to voltage application.
  • the piezoelectric element 10 is formed by laminating five layers of the piezoelectric film 12 by folding. Also, the piezoelectric element 10 is adhered to the vibration plate 62 by the adhesion layer 68 . As the piezoelectric film 12 expands and contracts, the piezoelectric element 10 also expands and contracts in the same direction. Due to the expansion and contraction of the piezoelectric element 10, the vibration plate 62 is bent and, as a result, vibrates in the thickness direction. This vibration in the thickness direction causes the diaphragm 62 to generate sound. That is, the diaphragm 62 vibrates according to the magnitude of the voltage (driving voltage) applied to the piezoelectric film 12 and generates sound according to the driving voltage applied to the piezoelectric film 12 .
  • a general piezoelectric film made of a polymeric material such as PVDF the molecular chains are oriented in the stretching direction by stretching in the uniaxial direction after the polarization treatment, and as a result, the piezoelectric properties in the stretching direction are large. known to be obtained. Therefore, a general piezoelectric film has in-plane anisotropy in piezoelectric properties, and anisotropy in the amount of expansion and contraction in the plane direction when a voltage is applied.
  • the piezoelectric property Since a large piezoelectric property is obtained, the piezoelectric property has no in-plane anisotropy and expands and contracts isotropically in all directions in the plane direction. That is, in the illustrated piezoelectric element 10, the piezoelectric film 12 shown in FIG. 4, which constitutes the piezoelectric element 10, expands and contracts isotropically two-dimensionally. According to the piezoelectric element 10 in which such a piezoelectric film 12 that expands and contracts isotropically two-dimensionally is laminated, a large force is generated compared to the case where a general piezoelectric film such as PVDF that expands and contracts greatly in only one direction is laminated. can vibrate the diaphragm 62, and a louder and more beautiful sound can be generated.
  • the illustrated piezoelectric element 10 is formed by laminating five such piezoelectric films 12 .
  • the adjoining piezoelectric films 12 are further attached to each other with an adhesive layer 20 . Therefore, even if the rigidity of each piezoelectric film 12 is low and the expansion/contraction force is small, by laminating the piezoelectric films 12 , the rigidity is increased and the expansion/contraction force of the piezoelectric element 10 is increased. As a result, even if the diaphragm 62 has a certain degree of rigidity, the piezoelectric element 10 sufficiently bends the diaphragm 62 with a large force and sufficiently vibrates the diaphragm 62 in the thickness direction.
  • a sound can be generated in the diaphragm 62 .
  • the preferable thickness of the piezoelectric layer 26 is about 300 ⁇ m at most. 12 can be stretched.
  • Such a piezoelectric element of the present invention can be used, for example, in addition to the piezoelectric speaker as described above, for various sensors, acoustic devices, haptics, ultrasonic transducers, actuators, dampers, and vibration power generators. etc., it is suitably used for various purposes.
  • sensors using the piezoelectric element of the present invention are exemplified by sound wave sensors, ultrasonic sensors, pressure sensors, tactile sensors, strain sensors, vibration sensors, and the like.
  • Sensors using the piezoelectric film and laminated piezoelectric element of the present invention are particularly useful for inspections at manufacturing sites, such as infrastructure inspections such as crack detection, and foreign matter contamination detection.
  • Examples of acoustic devices using the piezoelectric element of the present invention include microphones, pickups, and various known speakers and exciters, in addition to the piezoelectric speakers (exciters) described above.
  • Specific applications of the acoustic device using the piezoelectric element of the present invention include noise cancellers used in cars, trains, airplanes, robots, etc., artificial vocal cords, buzzers for preventing insects and vermin from entering, and voice output functions. Examples include furniture, wallpaper, photographs, helmets, goggles, headrests, signage, and robots.
  • Examples of applications of haptics using the piezoelectric element of the present invention include automobiles, smart phones, smart watches, and game machines.
  • Examples of ultrasonic transducers using the piezoelectric element of the present invention include ultrasonic probes and hydrophones.
  • Examples of applications of the actuator using the piezoelectric element of the present invention include prevention of adhesion of water droplets, transportation, stirring, dispersion, polishing, and the like.
  • Examples of application of the damping material using the piezoelectric element of the present invention include containers, vehicles, buildings, and sports equipment such as skis and rackets.
  • application examples of the vibration power generator using the piezoelectric element of the present invention include roads, floors, mattresses, chairs, shoes, tires, wheels, and personal computer keyboards.
  • a piezoelectric film as shown in FIG. 4 was produced by the method shown in FIGS. First, cyanoethylated PVA (CR-V, manufactured by Shin-Etsu Chemical Co., Ltd.) was dissolved in dimethylformamide (DMF) at the following compositional ratio. After that, PZT particles as piezoelectric particles were added to this solution at the following composition ratio, and the mixture was stirred with a propeller mixer (rotation speed: 2000 rpm) to prepare a paint for forming a piezoelectric layer.
  • cyanoethylated PVA CR-V, manufactured by Shin-Etsu Chemical Co., Ltd.
  • DMF dimethylformamide
  • ⁇ PZT particles ⁇ 300 parts by mass ⁇ Cyanoethylated PVA ⁇ 30 parts by mass ⁇ DMF ⁇ 70 parts by mass
  • Mixed powder obtained by wet-mixing in a ball mill was fired at 800° C. for 5 hours and then pulverized.
  • two sheets were prepared by vacuum-depositing a copper thin film with a thickness of 20 nm on a PET film with a thickness of 4 ⁇ m. That is, in this example, the first electrode layer and the second electrode layer are 20 nm-thick copper-evaporated thin films, and the first protective layer and the second protective layer are 4 ⁇ m-thick PET films.
  • a slide coater was used to apply the previously prepared paint for forming the piezoelectric layer onto the copper thin film (second electrode layer) of one sheet.
  • the sheet-like material coated with the paint was dried by heating on a hot plate at 120° C. to evaporate the DMF.
  • a laminate having a second electrode layer made of copper on a second protective layer made of PET and a piezoelectric layer (polymer composite piezoelectric layer) having a thickness of 50 ⁇ m thereon was produced. .
  • the produced piezoelectric layer (laminate) was calendered using a pair of heating rollers.
  • the temperature of the heating roller pair was set to 100.degree.
  • the produced piezoelectric layer was subjected to a polarization treatment in the thickness direction.
  • Another sheet was laminated on the laminate with the copper thin film (first electrode layer) facing the piezoelectric layer.
  • the laminated body and the sheet-shaped material are thermocompressed at a temperature of 120° C. using a pair of heating rollers, thereby bonding the piezoelectric layer and the first electrode layer, as shown in FIG. A piezoelectric film was produced.
  • Example 1 The produced piezoelectric film was cut into a rectangle of 20 ⁇ 25 cm. As shown in FIG. 10, this piezoelectric film was repeatedly attached by providing an adhesive layer, folding back the piezoelectric film, and pressing with a roller at intervals of 5 cm in a direction of 25 cm. As a result, a piezoelectric element having a planar shape of 20 ⁇ 5 cm as shown in FIG. 2 was manufactured by laminating five layers of piezoelectric films and adhering adjacently laminated piezoelectric films. Therefore, the side of the piezoelectric element with a length of 20 cm becomes a ridgeline (folding line). A thermoplastic resin was used for the adhesive layer.
  • a roller having a length of 20 cm or more was used, and the piezoelectric film was pressed and adhered while moving in the folding direction so as to press the entire area in the direction of the ridge line.
  • the roller was heated above the temperature at which the thermoplastic resin melts.
  • the pressing force of the roller was partially weakened in the middle. The position where the pressing force is weakened was the same for all layers.
  • Example 2 and Comparative Example 1 A piezoelectric element was produced in the same manner as in Example 1, except that the pressing force of the roller and the position at which the pressing force is weakened were changed when the piezoelectric elements were laminated.
  • a central measurement line x1 is set at the center of the ridgeline direction, and measurement lines x2 and x3 are set at positions 1 cm inward from the end, and A measurement line x4 was set between the center measurement line x1 and the measurement line x2, and a measurement line x5 was set between the center measurement line x1 and the measurement line x3.
  • the surface shape was measured using a contour shape measuring instrument (CV-3000, manufactured by Mitutoyo Co., Ltd.), and the position of the highest point was detected.
  • the shortest distance between the highest point and the ridgeline of the piezoelectric element was measured for each measurement line, and the average value was obtained. This average value was taken as the shortest distance L between the ridge line and the thickest portion in the piezoelectric element.
  • the position in the ridgeline direction away from the ridgeline by the shortest distance L in the folding direction was defined as the thickest portion of the piezoelectric element. Results are shown in the table below.
  • the determined thickness T1 of the thickest portion and the determined thickness T2 of the folded portion were measured.
  • the thickness of the folded portion is the interval in the stacking direction between both surfaces of the piezoelectric element at the positions of the ends of the adhesive layers on both ends of the piezoelectric film.
  • the thickness of the thickest part and the thickness of the folded part are both measured at the set center measurement line x1 and the measurement lines x2 to x5, and the average value is the thickness T1 of the thickest part and the thickness of the folded part.
  • the thickness of the thickest portion and the thickness of the folded portion were measured using a ⁇ 2 mm flat-type probe and a digimatic indicator (ID-S112X manufactured by Mitutoyo Co., Ltd.). Results are shown in the table below.
  • the fabricated piezoelectric element was cut along the set central measurement line x1 and the measurement lines x2 to x5, and the section of the determined thickest portion was observed with an SEM. From the SEM image, the thickness of each adhesive layer at the thickest portion in each cross section was measured. The thickness t of the adhesive layer at the thickest portion of the piezoelectric element was obtained by averaging the thicknesses of all the adhesive layers at the thickest portions. In this example, since there are four adhesive layers and five measurement lines, the thickness t of the adhesive layer is the average value of the thicknesses of the adhesive layers at 20 locations. Results are shown in the table below. In addition, the thickness t of the adhesive layer was measured after performing the evaluation described later.
  • the shortest distance between the ridge line (end of the folded part) and the thickest part of the piezoelectric element is The piezoelectric element of the present invention, in which L is at least 50 times the thickness t of the adhesive layer at the thickest portion (L ⁇ 50*t), is able to maintain the piezoelectricity at the folded portion even when pressure is applied to the entire surface of the planar shape. No rupture of the body layer and electrode layer occurred. Therefore, when the piezoelectric element of the present invention is pressed/bonded to the diaphragm to form a piezoelectric speaker, the piezoelectric layer and the electrode layer of the folded portion are not broken, and the desired sound is produced. It can output the sound of pressure.
  • Example 1 in which the thickness T1 of the thickest portion with respect to the thickness T2 of the folded portion is 115% or more, which is a preferable range, has a lower ESR after pressing than Example 2, which does not satisfy this. . Therefore, the piezoelectric element of Example 1 can be driven more stably and efficiently after being pressed/adhered to the diaphragm to constitute the piezoelectric speaker.
  • the piezoelectric element of Comparative Example 1 in which the shortest distance L is less than 50 times the thickness t of the adhesive layer, when pressure is applied to the entire surface of the planar shape, the piezoelectric film at the folded portion is It is believed that the piezoelectric layer and the electrode layer were fractured at the folded portion, probably due to strong surface pressure. Therefore, when this piezoelectric element is pressed/bonded to a diaphragm to form a piezoelectric speaker, the piezoelectric layer and the electrode layer at the folded portion are broken, and sound with the desired sound pressure is output. may not be possible. Also, the piezoelectric element of Comparative Example 1 has a higher ESR after pressing than the product of the present invention. Therefore, the piezoelectric element of Comparative Example 1 may be unstable in driving and deteriorated in efficiency after being pressed/bonded to the diaphragm to constitute the piezoelectric speaker. From the above results, the effect of the present invention is clear.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Piezo-Electric Transducers For Audible Bands (AREA)
PCT/JP2022/034230 2021-09-24 2022-09-13 圧電素子および圧電スピーカー WO2023048022A1 (ja)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2020196850A1 (ja) * 2019-03-28 2020-10-01 富士フイルム株式会社 圧電フィルム、積層圧電素子および電気音響変換器
WO2020241049A1 (ja) * 2019-05-27 2020-12-03 ソニー株式会社 オーディオ再生装置及びオーディオデバイス
CN113066924A (zh) * 2021-03-18 2021-07-02 业成科技（成都）有限公司 薄膜压电感应元件及其制造方法、感测装置以及终端
WO2021200455A1 (ja) * 2020-03-31 2021-10-07 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

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2020196850A1 (ja) * 2019-03-28 2020-10-01 富士フイルム株式会社 圧電フィルム、積層圧電素子および電気音響変換器
WO2020241049A1 (ja) * 2019-05-27 2020-12-03 ソニー株式会社 オーディオ再生装置及びオーディオデバイス
WO2021200455A1 (ja) * 2020-03-31 2021-10-07 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
CN113066924A (zh) * 2021-03-18 2021-07-02 业成科技（成都）有限公司 薄膜压电感应元件及其制造方法、感测装置以及终端

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