WO2023048022A1 - Piezoelectric element and piezoelectric speaker - Google Patents
Piezoelectric element and piezoelectric speaker Download PDFInfo
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- 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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Images
Classifications
-
- 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.
Abstract
The present invention addresses the problem of providing: a piezoelectric element in which a piezoelectric film is folded over and laminated, and which is capable of preventing breakage of electrode layers or the like in the folded-over sections when pressure is applied; and a piezoelectric speaker using this piezoelectric element. This problem is solved by satisfying "L ≥ 50 * t" when an adhesion layer which is laminated and adhered to the neighboring piezoelectric film, t denotes the thickness of the adhesion layer at the thickest section of the piezoelectric element, and L is the shortest distance between the folded-over section of the piezoelectric film and the thickest section of the piezoelectric element.
Description
本発明は、圧電素子、および、この圧電素子を用いる圧電スピーカーに関する。
The present invention relates to a piezoelectric element and a piezoelectric speaker using this piezoelectric element.
各種の物品に接触して取り付けることで、物品を振動させて音を出す、いわゆるエキサイター（励起子）が、各種の用途に利用されている。
例えば、オフィスであれば、プレゼンテーションおよび電話会議等の際に、会議用テーブル、ホワイトボードおよびスクリーン等にエキサイターを取り付けることで、スピーカーの代わりに音声を出力することができる。自動車等の車両であれば、コンソール、Ａピラーおよび天井等にエキサイターを取り付けることで、ガイド音、警告音および音楽等を鳴らすことができる。また、ハイブリット車および電気自動車のように、エンジン音が出ない自動車の場合には、バンパー等にエキサイターを取り付けることで、バンパー等から車両接近通報音を出すことができる。 2. Description of the Related Art So-called 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. In the case of 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. In addition, in the case of a vehicle such as a hybrid vehicle or an electric vehicle in which an engine sound is not generated, by attaching an exciter to a bumper or the like, a vehicle approach notification sound can be emitted from the bumper or the like.
例えば、オフィスであれば、プレゼンテーションおよび電話会議等の際に、会議用テーブル、ホワイトボードおよびスクリーン等にエキサイターを取り付けることで、スピーカーの代わりに音声を出力することができる。自動車等の車両であれば、コンソール、Ａピラーおよび天井等にエキサイターを取り付けることで、ガイド音、警告音および音楽等を鳴らすことができる。また、ハイブリット車および電気自動車のように、エンジン音が出ない自動車の場合には、バンパー等にエキサイターを取り付けることで、バンパー等から車両接近通報音を出すことができる。 2. Description of the Related Art So-called 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. In the case of 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. In addition, in the case of a vehicle such as a hybrid vehicle or an electric vehicle in which an engine sound is not generated, by attaching an exciter to a bumper or the like, a vehicle approach notification sound can be emitted from the bumper or the like.
このようなエキサイターにおいて振動を生じる可変素子としては、コイルとマグネットとの組み合わせ、ならびに、偏心モータおよび線形共振モータ等の振動モータ等が知られている。
これらの可変素子は、薄型化が困難である。特に、振動モータは、振動力を増加するためには質量体を大きくする必要がある、振動の程度を調節するための周波数変調が難しく応答速度が遅い等の難点がある。 As 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. In particular, 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.
これらの可変素子は、薄型化が困難である。特に、振動モータは、振動力を増加するためには質量体を大きくする必要がある、振動の程度を調節するための周波数変調が難しく応答速度が遅い等の難点がある。 As 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. In particular, 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.
一方、近年では、例えば、可撓性を有するディスプレイに対応する要求等に応じて、スピーカーにも、可撓性が要求されている。しかしながら、このようなエキサイターと振動板とからなる構成では、可撓性を有するスピーカーへの対応は困難である。
On the other hand, in recent years, for example, speakers are also required to be flexible in response to the demand for flexible displays. However, it is difficult to deal with a speaker having flexibility with such a configuration consisting of an exciter and a diaphragm.
可撓性を有する振動板に、可撓性を有するエキサイターを貼着することで、可撓性を有するスピーカーとすることも考えられる。
例えば、特許文献１には、２つの薄膜電極で圧電体層を挟持した圧電フィルムを、複数層、積層した、積層圧電素子が記載されている。この積層圧電素子における圧電フィルムは、厚さ方向に分極されたものであり、さらに、隣接する圧電フィルムの分極方向を逆にしている。
この積層圧電素子は、圧電フィルムに通電することにより、圧電フィルムが面方向に伸縮する。そのため、この積層圧電素子をエキサイターとして振動板に貼着することにより、積層された圧電フィルムの伸縮運動によって、振動板が撓んで板面と直交する方向に振動し、振動板が音声を出力する圧電スピーカーを実現できる。 A flexible speaker may be provided by attaching a flexible exciter to a flexible diaphragm.
For example,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.
In this laminated piezoelectric element, the piezoelectric film expands and contracts in the plane direction by energizing the piezoelectric film. Therefore, by attaching 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.
例えば、特許文献１には、２つの薄膜電極で圧電体層を挟持した圧電フィルムを、複数層、積層した、積層圧電素子が記載されている。この積層圧電素子における圧電フィルムは、厚さ方向に分極されたものであり、さらに、隣接する圧電フィルムの分極方向を逆にしている。
この積層圧電素子は、圧電フィルムに通電することにより、圧電フィルムが面方向に伸縮する。そのため、この積層圧電素子をエキサイターとして振動板に貼着することにより、積層された圧電フィルムの伸縮運動によって、振動板が撓んで板面と直交する方向に振動し、振動板が音声を出力する圧電スピーカーを実現できる。 A flexible speaker may be provided by attaching a flexible exciter to a flexible diaphragm.
For example,
In this laminated piezoelectric element, the piezoelectric film expands and contracts in the plane direction by energizing the piezoelectric film. Therefore, by attaching 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.
特許文献１のような積層圧電素子において、圧電フィルムを積層する方法の１つとして、特許文献１にも記載されるように、圧電フィルムを蛇腹状に折り返すことにより、複数層の圧電フィルムを積層する方法が考えられる。
カットシート状の圧電フィルムを、複数枚、積層した場合には、個々の圧電フィルム毎に、電極層と電源等の外部装置とを接続する必要が生じる。これに対して、圧電フィルムを折り返して、複数層を積層した場合には、圧電フィルムは１枚であるので、電極層と電源等の外部装置との接続は、１か所でよい。 In a laminated piezoelectric element such as that disclosed inPatent Document 1, as one method of stacking piezoelectric films, as described in Patent Document 1, a piezoelectric film is folded in a bellows shape to stack a plurality of piezoelectric films. We can think of a way to do this.
When a plurality of cut-sheet piezoelectric films are laminated, it is necessary to connect the electrode layer and an external device such as a power supply for each individual piezoelectric film. On the other hand, when 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.
カットシート状の圧電フィルムを、複数枚、積層した場合には、個々の圧電フィルム毎に、電極層と電源等の外部装置とを接続する必要が生じる。これに対して、圧電フィルムを折り返して、複数層を積層した場合には、圧電フィルムは１枚であるので、電極層と電源等の外部装置との接続は、１か所でよい。 In a laminated piezoelectric element such as that disclosed in
When a plurality of cut-sheet piezoelectric films are laminated, it is necessary to connect the electrode layer and an external device such as a power supply for each individual piezoelectric film. On the other hand, when 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.
ところで、積層圧電素子をエキサイターとして用いる場合には、前述のように、積層圧電素子を振動板に貼着する必要がある。
積層圧電素子と振動板との貼着は、例えば、粘着剤等の貼着剤を介して、積層圧電素子を振動板に押圧することで行う。 By the way, when the laminated piezoelectric element is 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.
積層圧電素子と振動板との貼着は、例えば、粘着剤等の貼着剤を介して、積層圧電素子を振動板に押圧することで行う。 By the way, when the laminated piezoelectric element is 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.
ここで、圧電フィルムを折り返して積層した積層圧電素子では、この際の押圧によって、圧電フィルムに面圧がかかる。この面圧が圧電フィルムの折り返し部にかかると、圧電フィルムに負担がかかり、場合によっては、折り返し部において、電極層および／または圧電体層が破断してしまうという問題がある。
Here, in the laminated piezoelectric element in which the piezoelectric film is folded and laminated, surface pressure is applied to the piezoelectric film by pressing at this time. When 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.
また、特許文献１に記載される積層圧電素子において、圧電フィルムは、圧電体層として、例えば、高分子材料に圧電体粒子を分散してなる高分子複合圧電体を用いる。そのため、この積層圧電素子は、非常に良好な可撓性を有する。
従って、この積層圧電素子を、可撓性を有する振動板に貼着することで、可撓性を有し、折り曲げおよび巻取りが可能な圧電スピーカーを実現できる。
ここで、振動板の巻取りの際には、積層圧電素子も振動板と共に巻き取られるが、この巻取りの際に、先と同様、折り返し部の圧電フィルムに面圧がかかり、場合によっては、電極層および／または圧電体層が破断してしまう。 Further, in the laminated piezoelectric element described inPatent Document 1, 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.
Here, when the diaphragm is 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.
従って、この積層圧電素子を、可撓性を有する振動板に貼着することで、可撓性を有し、折り曲げおよび巻取りが可能な圧電スピーカーを実現できる。
ここで、振動板の巻取りの際には、積層圧電素子も振動板と共に巻き取られるが、この巻取りの際に、先と同様、折り返し部の圧電フィルムに面圧がかかり、場合によっては、電極層および／または圧電体層が破断してしまう。 Further, in the laminated piezoelectric element described in
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.
Here, when the diaphragm is 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.
本発明の目的は、このような従来技術の問題点を解決することにあり、圧電フィルムを折り返して積層した圧電素子であって、圧力がかけられた場合に、圧電フィルムの折り返し部で電極層等が破断することを防止できる圧電素子、および、この圧電素子を用いる圧電スピーカーを提供することにある。
SUMMARY OF THE INVENTION 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.
このような目的を達成するために、本発明は、以下の構成を有する。
［１］ 可撓性を有する圧電フィルムを折り返すことで、圧電フィルムを複数層、積層した圧電素子において、
積層されて隣接する圧電フィルムを貼着する貼着層を有し、
圧電素子の最厚部における貼着層の厚さをｔ、圧電フィルムの折り返し部の端部と圧電素子の最厚部との最短距離をＬとした際に、『Ｌ≧５０＊ｔ』を満たすことを特徴とする圧電素子。
［２］ 圧電フィルムの積層方向から見た際に矩形状であり、
矩形の長辺と、圧電フィルムの折り返し線とが一致する、［１］に記載の圧電素子。
［３］ 最厚部の厚さが、圧電フィルムの折り返し部の厚さの１１５％以上である、［１］または［２］に記載の圧電素子。
［４］ 圧電フィルムが、圧電体層と、圧電体層の両面に設けられた電極層と、電極層を覆って設けられた保護層と、を有する、［１］～［３］のいずれかに記載の圧電素子。
［５］ 圧電体層が、高分子材料中に圧電体粒子を有する高分子複合圧電体である、［４］に記載の圧電素子。
［６］ 高分子材料が、シアノエチル基を有する、［５］に記載の圧電素子。
［７］ 高分子材料が、シアノエチル化ポリビニルアルコールである、［６］に記載の圧電素子。
［８］ 振動板に、［１］～［７］のいずれかに記載の圧電素子を貼着してなる、圧電スピーカー。 In order to achieve such an object, 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 .
[5] The piezoelectric element according to [4], wherein the piezoelectric layer is a polymeric composite piezoelectric body having piezoelectric particles in a polymeric material.
[6] The piezoelectric element according to [5], wherein the polymeric material has a cyanoethyl group.
[7] The piezoelectric element according to [6], wherein the polymeric material is cyanoethylated polyvinyl alcohol.
[8] A piezoelectric speaker comprising a diaphragm and the piezoelectric element according to any one of [1] to [7] attached thereto.
［１］ 可撓性を有する圧電フィルムを折り返すことで、圧電フィルムを複数層、積層した圧電素子において、
積層されて隣接する圧電フィルムを貼着する貼着層を有し、
圧電素子の最厚部における貼着層の厚さをｔ、圧電フィルムの折り返し部の端部と圧電素子の最厚部との最短距離をＬとした際に、『Ｌ≧５０＊ｔ』を満たすことを特徴とする圧電素子。
［２］ 圧電フィルムの積層方向から見た際に矩形状であり、
矩形の長辺と、圧電フィルムの折り返し線とが一致する、［１］に記載の圧電素子。
［３］ 最厚部の厚さが、圧電フィルムの折り返し部の厚さの１１５％以上である、［１］または［２］に記載の圧電素子。
［４］ 圧電フィルムが、圧電体層と、圧電体層の両面に設けられた電極層と、電極層を覆って設けられた保護層と、を有する、［１］～［３］のいずれかに記載の圧電素子。
［５］ 圧電体層が、高分子材料中に圧電体粒子を有する高分子複合圧電体である、［４］に記載の圧電素子。
［６］ 高分子材料が、シアノエチル基を有する、［５］に記載の圧電素子。
［７］ 高分子材料が、シアノエチル化ポリビニルアルコールである、［６］に記載の圧電素子。
［８］ 振動板に、［１］～［７］のいずれかに記載の圧電素子を貼着してなる、圧電スピーカー。 In order to achieve such an object, 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 .
[5] The piezoelectric element according to [4], wherein the piezoelectric layer is a polymeric composite piezoelectric body having piezoelectric particles in a polymeric material.
[6] The piezoelectric element according to [5], wherein the polymeric material has a cyanoethyl group.
[7] The piezoelectric element according to [6], wherein the polymeric material is cyanoethylated polyvinyl alcohol.
[8] A piezoelectric speaker comprising a diaphragm and the piezoelectric element according to any one of [1] to [7] attached thereto.
このような本発明によれば、圧電フィルムを折り返して積層した圧電素子において、圧力がかけられた場合に、圧電フィルムの折り返し部で電極層等が破断することを防止できる。
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.
以下、本発明の圧電素子および圧電スピーカーについて、添付の図面に示される好適実施態様を基に、詳細に説明する。
The piezoelectric element and piezoelectric speaker of the present invention will be described in detail below based on preferred embodiments shown in the accompanying drawings.
以下に記載する構成要件の説明は、本発明の代表的な実施態様に基づいてなされることがあるが、本発明はそのような実施態様に限定されるものではない。
また、以下に示す図は、本発明の圧電素子および圧電スピーカーを説明するための概念的な図である。従って、各部材および各部位の大きさ、厚さ、形状、ならびに、位置関係等は、実際の物とは異なる。 The description of the constituent elements described below may be made based on representative embodiments of the present invention, but the present invention is not limited to such embodiments.
Also, the diagrams shown below are conceptual diagrams for explaining the piezoelectric element and the piezoelectric speaker of the present invention. Therefore, the size, thickness, shape, positional relationship, etc. of each member and each part differ from the actual product.
また、以下に示す図は、本発明の圧電素子および圧電スピーカーを説明するための概念的な図である。従って、各部材および各部位の大きさ、厚さ、形状、ならびに、位置関係等は、実際の物とは異なる。 The description of the constituent elements described below may be made based on representative embodiments of the present invention, but the present invention is not limited to such embodiments.
Also, the diagrams shown below are conceptual diagrams for explaining the piezoelectric element and the piezoelectric speaker of the present invention. Therefore, the size, thickness, shape, positional relationship, etc. of each member and each part differ from the actual product.
本発明において、「～」を用いて表される数値範囲は、「～」の前後に記載される数値を下限値および上限値として含む範囲を意味する。
さらに、本発明において、電極層および保護層等に付している第１および第２とは、基本的に同じである２つの部材を区別し、本発明の圧電素子および圧電スピーカーを説明するために、便宜的に付しているものである。従って、これらの部材における第１および第２には、技術的な意味は無く、また、実際の使用状態および互いの位置関係等とは、無関係である。 In 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.
Furthermore, in the present invention, 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.
さらに、本発明において、電極層および保護層等に付している第１および第２とは、基本的に同じである２つの部材を区別し、本発明の圧電素子および圧電スピーカーを説明するために、便宜的に付しているものである。従って、これらの部材における第１および第２には、技術的な意味は無く、また、実際の使用状態および互いの位置関係等とは、無関係である。 In 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.
Furthermore, in the present invention, 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.
図１に、本発明の圧電素子の一例を概念的に示す。なお、図１において、上段は、圧電素子１０の正面図を、下段は平面図を、それぞれ示す。
なお、正面図とは、本発明の圧電素子を、後述する圧電フィルムの面方向に見た図である。また、平面図とは、本発明の圧電素子を、後述する圧電フィルムの積層方向から見た図である。言い換えれば、平面図とは、圧電素子を、圧電フィルム１２の主面と直交する方向から見た図である。主面とは、シート状物（フィルム、板状物、層）の最大面であり、通常、シート状物の厚さ方向の両面である。
以下の説明では、本発明の圧電素子を平面図と同じ方向から見た場合を、便宜的に『平面視』ともいう。また、本発明の圧電素子を平面視した際の形状、すなわち、平面図における本発明の圧電素子の形状を、便宜的に『平面形状』ともいう。 FIG. 1 conceptually shows an example of the piezoelectric element of the present invention. In FIG. 1, the upper part shows a front view of thepiezoelectric element 10, and the lower part shows a plan view.
Note that 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. In other words, the plan view is a view of the piezoelectric element viewed from a direction perpendicular to the main surface of thepiezoelectric 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.
In the following description, 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. Further, the 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.
なお、正面図とは、本発明の圧電素子を、後述する圧電フィルムの面方向に見た図である。また、平面図とは、本発明の圧電素子を、後述する圧電フィルムの積層方向から見た図である。言い換えれば、平面図とは、圧電素子を、圧電フィルム１２の主面と直交する方向から見た図である。主面とは、シート状物（フィルム、板状物、層）の最大面であり、通常、シート状物の厚さ方向の両面である。
以下の説明では、本発明の圧電素子を平面図と同じ方向から見た場合を、便宜的に『平面視』ともいう。また、本発明の圧電素子を平面視した際の形状、すなわち、平面図における本発明の圧電素子の形状を、便宜的に『平面形状』ともいう。 FIG. 1 conceptually shows an example of the piezoelectric element of the present invention. In FIG. 1, the upper part shows a front view of the
Note that 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. In other words, the plan view is a view of the piezoelectric element viewed from a direction perpendicular to the main surface of the
In the following description, 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. Further, the 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.
図１に示す圧電素子１０は、可撓性を有する圧電フィルム１２を、複数回、蛇腹状に折り返すことによって、圧電フィルム１２を、複数層、積層したものである。圧電フィルム１２は、圧電体層２６の一面に第１電極層２８を、他方の面に第２電極層３０を有し、第１電極層２８の表面に第１保護層３２を、第２電極層３０の表面に第２保護層３４を、それぞれ、設けたものである。
また、圧電素子１０においては、折り返しによって積層された隣接する圧電フィルム１２は、貼着層２０によって貼着されている。 Apiezoelectric 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.
Also, in thepiezoelectric element 10 , the adjacent piezoelectric films 12 laminated by folding are attached by the adhesive layer 20 .
また、圧電素子１０においては、折り返しによって積層された隣接する圧電フィルム１２は、貼着層２０によって貼着されている。 A
Also, in the
図示例の圧電素子１０は、矩形（長方形）の圧電フィルム１２を、等間隔で、４回、折り返すことにより、５層の圧電フィルム１２を積層したものである。
従って、圧電素子１０の平面形状は、矩形になる。 The illustratedpiezoelectric 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 thepiezoelectric element 10 is rectangular.
従って、圧電素子１０の平面形状は、矩形になる。 The illustrated
Therefore, the planar shape of the
本発明の圧電素子１０において、矩形の圧電フィルム１２を折り返す場合には、圧電フィルム１２の折り返しによって形成される折り返し線は、圧電素子１０の平面形状において、長手方向に一致しても、短手方向に一致してもよい。
以下の説明では、圧電フィルム１２の折り返しによって形成される折り返し線、すなわち、折り返し部の端部の外側の頂部の線を、便宜的に『稜線』ともいう。 In thepiezoelectric element 10 of the present invention, when the rectangular piezoelectric film 12 is folded back, 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.
In the following description, the fold line formed by folding thepiezoelectric 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.
以下の説明では、圧電フィルム１２の折り返しによって形成される折り返し線、すなわち、折り返し部の端部の外側の頂部の線を、便宜的に『稜線』ともいう。 In the
In the following description, the fold line formed by folding the
一例として、平面形状が２０×５ｃｍの矩形である圧電素子１０を例に説明する。
本発明の圧電素子１０は、図２に概念的に示すように、２０×２５ｃｍの矩形の圧電フィルム１２を、２５ｃｍの辺の方向に５ｃｍずつ折り返した、稜線が長手方向である２０ｃｍの圧電素子１０でもよい。
あるいは、本発明の圧電素子１０は、図３に概念的に示すように、１００×５ｃｍの矩形の圧電フィルム１２を、１００ｃｍの辺の方向に２０ｃｍずつ折り返した、稜線が短手方向である５ｃｍの圧電素子１０でもよい。
なお、図２および図３では、後述する圧電素子１０の最厚部は省略している。 As an example, thepiezoelectric element 10 having a rectangular planar shape of 20×5 cm will be described.
As conceptually shown in FIG. 2, thepiezoelectric 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.
Alternatively, as conceptually shown in FIG. 3, thepiezoelectric 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 thepiezoelectric element 10, which will be described later, is omitted.
本発明の圧電素子１０は、図２に概念的に示すように、２０×２５ｃｍの矩形の圧電フィルム１２を、２５ｃｍの辺の方向に５ｃｍずつ折り返した、稜線が長手方向である２０ｃｍの圧電素子１０でもよい。
あるいは、本発明の圧電素子１０は、図３に概念的に示すように、１００×５ｃｍの矩形の圧電フィルム１２を、１００ｃｍの辺の方向に２０ｃｍずつ折り返した、稜線が短手方向である５ｃｍの圧電素子１０でもよい。
なお、図２および図３では、後述する圧電素子１０の最厚部は省略している。 As an example, the
As conceptually shown in FIG. 2, the
Alternatively, as conceptually shown in FIG. 3, the
2 and 3, the thickest portion of the
しかしながら、本発明の圧電素子１０は、図２に示す、平面形状が矩形で、かつ、稜線すなわち折り返しによる端部の線（折り返し線）が長辺と一致する構成が好ましい。
このような構成とすることにより、圧電素子１０の製造が容易になる、生産性を高くできる、折り返し部（屈曲部）での電流密度を低くできる等の点で好ましい。 However, as shown in FIG. 2, thepiezoelectric 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.
Such a configuration is preferable in that thepiezoelectric element 10 can be manufactured easily, the productivity can be increased, and the current density at the folded portion (bent portion) can be reduced.
このような構成とすることにより、圧電素子１０の製造が容易になる、生産性を高くできる、折り返し部（屈曲部）での電流密度を低くできる等の点で好ましい。 However, as shown in FIG. 2, the
Such a configuration is preferable in that the
なお、図１～３に示す圧電素子１０は、好ましい態様として、矩形の圧電フィルム１２を折り返すことで作製された、平面形状が矩形のものである。しかしながら、本発明の圧電素子において、圧電フィルム１２の形状は、矩形に制限はされず、各種の形状が利用可能である。
一例して、円形、角丸長方形（長円形）、楕円形、および、六角形等の多角形等が例示される。 Thepiezoelectric element 10 shown in FIGS. 1 to 3 preferably has a rectangular planar shape, which is produced by folding a rectangular piezoelectric film 12 . However, in the piezoelectric element of the present invention, 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.
一例して、円形、角丸長方形（長円形）、楕円形、および、六角形等の多角形等が例示される。 The
Examples include circles, rounded rectangles (ovals), ellipses, and polygons such as hexagons.
上述のように、圧電素子１０は、圧電フィルム１２を、複数回、折り返して積層したものである。図示例の圧電素子１０は、圧電フィルム１２を４回、折り返すことで、５層の圧電フィルム１２を積層している。また、積層されて隣接する圧電フィルム１２を、貼着層２０によって貼着している。
本発明の圧電素子１０は、このように複数の圧電フィルム１２を積層し、隣接する圧電フィルム１２を貼着することにより、１枚の圧電フィルムを用いた場合に比して、圧電素子としての伸縮力を大きくできる。その結果、例えば後述する振動板を、大きな力で撓ませ、高い音圧の音声を出力することが可能になる。
また、本発明の圧電素子１０は、圧電素子が最も厚い位置である最厚部Ｍにおける貼着層２０の厚さをｔ、最厚部Ｍと稜線すなわち圧電フィルム１２の折り返し部の端部との最短距離をＬとした際に、『Ｌ≧５０＊ｔ』を満たす。本発明の圧電素子１０は、このような構成を有することにより、後述する振動板と貼着される場合等のように、圧電素子が積層方向に加圧された際に、圧電フィルム１２の折り返し部において、圧電体層２６および電極層が破断することを防止している。この点に関しては、後に詳述する。 As described above, thepiezoelectric element 10 is obtained by laminating the piezoelectric film 12 by folding it multiple times. In the illustrated piezoelectric element 10, five layers of the piezoelectric film 12 are laminated by folding the piezoelectric film 12 four times. In addition, the laminated and adjacent piezoelectric films 12 are attached by the adhesive layer 20 .
In thepiezoelectric 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. As a result, for example, a diaphragm, which will be described later, can be bent with a large force to output sound with a high sound pressure.
In thepiezoelectric element 10 of the present invention, t is the thickness of the adhesive layer 20 at the thickest portion M where the piezoelectric element is the thickest, and t is the thickness of the adhesive layer 20, and '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.
本発明の圧電素子１０は、このように複数の圧電フィルム１２を積層し、隣接する圧電フィルム１２を貼着することにより、１枚の圧電フィルムを用いた場合に比して、圧電素子としての伸縮力を大きくできる。その結果、例えば後述する振動板を、大きな力で撓ませ、高い音圧の音声を出力することが可能になる。
また、本発明の圧電素子１０は、圧電素子が最も厚い位置である最厚部Ｍにおける貼着層２０の厚さをｔ、最厚部Ｍと稜線すなわち圧電フィルム１２の折り返し部の端部との最短距離をＬとした際に、『Ｌ≧５０＊ｔ』を満たす。本発明の圧電素子１０は、このような構成を有することにより、後述する振動板と貼着される場合等のように、圧電素子が積層方向に加圧された際に、圧電フィルム１２の折り返し部において、圧電体層２６および電極層が破断することを防止している。この点に関しては、後に詳述する。 As described above, the
In the
In the
本発明の圧電素子１０において、圧電素子１０における圧電フィルム１２の積層数は、図示例の５層に制限はされない。すなわち、本発明の圧電素子１０は、圧電フィルム１２を３回以下、折り返した４層以下の圧電フィルム１２を積層したものでもよく、あるいは、圧電フィルム１２を５回以上、折り返した、６層以上の圧電フィルム１２を積層したものでもよい。
本発明の圧電素子において、圧電フィルム１２の積層数には、制限はないが、２～１０層が好ましく、３～７層がより好ましい。 In thepiezoelectric element 10 of the present invention, the number of layers of the piezoelectric film 12 in the piezoelectric element 10 is not limited to five layers in the illustrated example. In other words, 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.
In the piezoelectric element of the present invention, the number of layers of thepiezoelectric film 12 is not limited, but preferably 2 to 10 layers, more preferably 3 to 7 layers.
本発明の圧電素子において、圧電フィルム１２の積層数には、制限はないが、２～１０層が好ましく、３～７層がより好ましい。 In the
In the piezoelectric element of the present invention, the number of layers of the
圧電素子１０では折り返しによって積層された圧電フィルム１２において、積層方向に隣接する圧電フィルム１２同士は、貼着層２０によって貼着されている。
積層方向に隣接する圧電フィルム１２を貼着層２０によって貼着することにより、各圧電フィルム１２の伸縮を直接的に伝達することができ、圧電フィルム１２を積層した積層体として、無駄なく駆動することが可能になる。 In thepiezoelectric element 10 , in the piezoelectric films 12 laminated by folding, the piezoelectric films 12 adjacent to each other in the lamination direction are adhered by the adhesion layer 20 .
By attaching thepiezoelectric films 12 adjacent in the stacking direction with the adhesive 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.
積層方向に隣接する圧電フィルム１２を貼着層２０によって貼着することにより、各圧電フィルム１２の伸縮を直接的に伝達することができ、圧電フィルム１２を積層した積層体として、無駄なく駆動することが可能になる。 In the
By attaching the
本発明において、貼着層２０は、隣接する圧電フィルム１２を貼着可能であれば、公知の貼着剤（貼着材）が、各種、利用可能である。
従って、貼着層２０は、接着剤（接着材）からなる層でも、粘着剤（粘着材）からなる層でも、接着剤と粘着剤との両方の特徴を持った材料からなる層でもよい。なお、接着剤とは、貼り合わせる際には流動性を有し、その後、固体になる貼着剤である。また、粘着剤とは、貼り合わせる際にゲル状（ゴム状）の柔らかい固体で、その後もゲル状の状態が変化しない貼着剤である。
また、貼着層２０は、液体等の流動性を有する貼着剤を塗布して形成するものでも、シート状の貼着剤を用いて形成するものでもよい。 In the present invention, as theadhesive layer 20, various known adhesive agents (adhesive materials) can be used as long as the adjacent piezoelectric films 12 can be attached.
Therefore, thesticking 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. Note that 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.
Further, theadhesive 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.
従って、貼着層２０は、接着剤（接着材）からなる層でも、粘着剤（粘着材）からなる層でも、接着剤と粘着剤との両方の特徴を持った材料からなる層でもよい。なお、接着剤とは、貼り合わせる際には流動性を有し、その後、固体になる貼着剤である。また、粘着剤とは、貼り合わせる際にゲル状（ゴム状）の柔らかい固体で、その後もゲル状の状態が変化しない貼着剤である。
また、貼着層２０は、液体等の流動性を有する貼着剤を塗布して形成するものでも、シート状の貼着剤を用いて形成するものでもよい。 In the present invention, as the
Therefore, the
Further, the
ここで、圧電素子１０は、一例としてエキサイターとして用いられる。すなわち、圧電素子１０は、積層した複数枚の圧電フィルム１２を伸縮させることで、自身が伸縮し、例えば後述するように振動板６２を撓ませ、振動させて、音を発生させる。従って、圧電素子１０では、積層された各圧電フィルム１２の伸縮が、直接的に伝達されるのが好ましい。圧電フィルム１２の間に、振動を緩和するような粘性を有する物質が存在すると、圧電フィルム１２の伸縮のエネルギーの伝達効率が低くなってしまい、圧電素子１０の駆動効率が低下してしまう。
この点を考慮すると、貼着層２０は、粘着剤からなる粘着剤層よりも、固体で硬い貼着層２０が得られる、接着剤からなる接着剤層であるのが好ましい。より好ましい貼着層２０としては、具体的には、ポリエステル系接着剤およびスチレン・ブタジエンゴム（ＳＢＲ）系接着剤等の熱可塑タイプの接着剤からなる貼着層が好適に例示される。
接着は、粘着とは異なり、高い接着温度を求める際に有用である。また、熱可塑タイプの接着剤は『比較的低温、短時間、および、強接着』を兼ね備えており、好適である。 Here, thepiezoelectric element 10 is used as an exciter as an example. In other words, 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.
Considering this point, thesticking 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. Specifically, 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".
この点を考慮すると、貼着層２０は、粘着剤からなる粘着剤層よりも、固体で硬い貼着層２０が得られる、接着剤からなる接着剤層であるのが好ましい。より好ましい貼着層２０としては、具体的には、ポリエステル系接着剤およびスチレン・ブタジエンゴム（ＳＢＲ）系接着剤等の熱可塑タイプの接着剤からなる貼着層が好適に例示される。
接着は、粘着とは異なり、高い接着温度を求める際に有用である。また、熱可塑タイプの接着剤は『比較的低温、短時間、および、強接着』を兼ね備えており、好適である。 Here, the
Considering this point, the
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".
圧電素子１０において、貼着層２０の厚さには制限はなく、貼着層２０の形成材料に応じて、十分な貼着力を発現できる厚さを、適宜、設定すればよい。
ここで、圧電素子１０は、貼着層２０が薄い方が、圧電体層２６の伸縮エネルギー（振動エネルギー）の伝達効果を高くして、エネルギー効率を高くできる。また、貼着層２０が厚く剛性が高いと、圧電フィルム１２の伸縮を拘束する可能性もある。
この点を考慮すると、貼着層２０は、圧電体層２６よりも薄いのが好ましい。すなわち、圧電素子１０において、貼着層２０は、硬く、薄いのが好ましい。具体的には、貼着層２０の厚さは、貼着後の厚さで０．１～５０μｍが好ましく、０．１～３０μｍがより好ましく、０．１～１０μｍがさらに好ましい。 In thepiezoelectric element 10 , 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 .
Here, in thepiezoelectric element 10, the thinner the adhesive layer 20, the higher the effect of transmitting the expansion and contraction energy (vibration energy) of the piezoelectric layer 26, and the higher the energy efficiency. Also, if the adhesive layer 20 is thick and rigid, it may restrict the expansion and contraction of the piezoelectric film 12 .
Considering this point, theadhesive 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. Specifically, the thickness of the adhesive layer 20 is preferably 0.1 to 50 μm, more preferably 0.1 to 30 μm, even more preferably 0.1 to 10 μm after being attached.
ここで、圧電素子１０は、貼着層２０が薄い方が、圧電体層２６の伸縮エネルギー（振動エネルギー）の伝達効果を高くして、エネルギー効率を高くできる。また、貼着層２０が厚く剛性が高いと、圧電フィルム１２の伸縮を拘束する可能性もある。
この点を考慮すると、貼着層２０は、圧電体層２６よりも薄いのが好ましい。すなわち、圧電素子１０において、貼着層２０は、硬く、薄いのが好ましい。具体的には、貼着層２０の厚さは、貼着後の厚さで０．１～５０μｍが好ましく、０．１～３０μｍがより好ましく、０．１～１０μｍがさらに好ましい。 In the
Here, in the
Considering this point, the
本発明の圧電素子において、圧電フィルム１２は、曲げ伸ばし可能な可撓性を有するものであれば、公知の圧電フィルム１２が、各種、利用可能である。
なお、本発明において、可撓性を有するとは、一般的な解釈における可撓性を有すると同義であり、曲げること、および、撓めることが可能であることを示し、具体的には、破壊および損傷を生じることなく、曲げ伸ばしができることを示す。 In the piezoelectric element of the present invention, various knownpiezoelectric films 12 can be used as long as the piezoelectric film 12 is flexible enough to be bent and stretched.
In the present invention, 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.
なお、本発明において、可撓性を有するとは、一般的な解釈における可撓性を有すると同義であり、曲げること、および、撓めることが可能であることを示し、具体的には、破壊および損傷を生じることなく、曲げ伸ばしができることを示す。 In the piezoelectric element of the present invention, various known
In the present invention, 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.
本発明の圧電素子１０において、圧電フィルム１２は、好ましい態様として、圧電体層２６の両面に設けられた電極層と、電極層を覆って設けられる保護層とを有する。
図４に、圧電フィルム１２の一例を断面図で概念的に示す。図４等においては、図面を簡略化して構成を明確に示すために、ハッチングは省略する。
なお、以下の説明では、特に断りが無い場合には、『断面』とは、圧電フィルムの厚さ方向の断面を示す。圧電フィルムの厚さ方向とは、圧電フィルムの積層方向である。 In thepiezoelectric element 10 of the present invention, 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 thepiezoelectric 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.
In the following description, unless otherwise specified, "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.
図４に、圧電フィルム１２の一例を断面図で概念的に示す。図４等においては、図面を簡略化して構成を明確に示すために、ハッチングは省略する。
なお、以下の説明では、特に断りが無い場合には、『断面』とは、圧電フィルムの厚さ方向の断面を示す。圧電フィルムの厚さ方向とは、圧電フィルムの積層方向である。 In the
FIG. 4 conceptually shows an example of the
In the following description, unless otherwise specified, "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.
図４に示すように、図示例の圧電フィルム１２は、圧電体層２６と、圧電体層２６の一方の面に積層される第１電極層２８と、第１電極層２８に積層される第１保護層３２と、圧電体層２６の他方の面に積層される第２電極層３０と、第２電極層３０に積層される第２保護層３４と、を有する。
As shown in FIG. 4 , 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 .
上述のように、本発明の圧電素子１０は、１枚の圧電フィルム１２を折り返すことで、圧電フィルム１２を積層している。
そのため、複数枚の圧電フィルム１２を積層しているにも関わらず、圧電素子１０すなわち圧電フィルム１２を駆動するための電極の引き出しを、後述する各電極層につき１か所にすることができる。その結果、圧電素子１０の構成、および、電極の引き回しを簡易化でき、さらに、生産性にも優れる。また、一枚の圧電フィルム１２を折り返して積層するので、積層によって隣接する圧電フィルム同士が対面する電極層は、同極性になるので、電極層同士が接触しても、ショートは生じない。 As described above, in thepiezoelectric element 10 of the present invention, the piezoelectric films 12 are laminated by folding one piezoelectric film 12 .
Therefore, although a plurality ofpiezoelectric 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.
そのため、複数枚の圧電フィルム１２を積層しているにも関わらず、圧電素子１０すなわち圧電フィルム１２を駆動するための電極の引き出しを、後述する各電極層につき１か所にすることができる。その結果、圧電素子１０の構成、および、電極の引き回しを簡易化でき、さらに、生産性にも優れる。また、一枚の圧電フィルム１２を折り返して積層するので、積層によって隣接する圧電フィルム同士が対面する電極層は、同極性になるので、電極層同士が接触しても、ショートは生じない。 As described above, in the
Therefore, although a plurality of
圧電フィルム１２において、圧電体層２６は、公知の圧電体層が、各種、利用可能である。
圧電フィルム１２において、圧電体層２６は、図４に概念的に示すように、高分子材料を含む高分子マトリックス３８中に、圧電体粒子４０を含む、高分子複合圧電体であるのが好ましい。 In thepiezoelectric film 12 , various known piezoelectric layers can be used for the piezoelectric layer 26 .
In thepiezoelectric film 12, 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. .
圧電フィルム１２において、圧電体層２６は、図４に概念的に示すように、高分子材料を含む高分子マトリックス３８中に、圧電体粒子４０を含む、高分子複合圧電体であるのが好ましい。 In the
In the
ここで、高分子複合圧電体（圧電体層２６）は、次の用件を具備したものであるのが好ましい。なお、本発明において、常温とは、０～５０℃である。
（ｉ） 可撓性
例えば、携帯用として新聞や雑誌のように書類感覚で緩く撓めた状態で把持する場合、絶えず外部から、数Ｈｚ以下の比較的ゆっくりとした、大きな曲げ変形を受けることになる。この時、高分子複合圧電体が硬いと、その分大きな曲げ応力が発生し、高分子マトリックスと圧電体粒子との界面で亀裂が発生し、やがて破壊に繋がる恐れがある。従って、高分子複合圧電体には適度な柔らかさが求められる。また、歪みエネルギーを熱として外部へ拡散できれば応力を緩和することができる。従って、高分子複合圧電体の損失正接が適度に大きいことが求められる。
（ii） 音質
スピーカーは、２０Ｈｚ～２０ｋＨｚのオーディオ帯域の周波数で圧電体粒子を振動させ、その振動エネルギーによって振動板（高分子複合圧電体）全体が一体となって振動することで音が再生される。従って、振動エネルギーの伝達効率を高めるために高分子複合圧電体には適度な硬さが求められる。また、スピーカーの周波数特性が平滑であれば、曲率の変化に伴い最低共振周波数ｆ0が変化した際の音質の変化量も小さくなる。従って、高分子複合圧電体の損失正接は適度に大きいことが求められる。 Here, the polymer composite piezoelectric body (piezoelectric layer 26) preferably satisfies the following requirements. In the present invention, normal temperature is 0 to 50°C.
(i) 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. Moreover, stress can be relieved if strain energy can be diffused to the outside as heat. Therefore, it is required that the loss tangent of the polymer composite piezoelectric material is appropriately large.
(ii) Sound quality A speaker vibrates piezoelectric particles at frequencies in the audio band of 20 Hz to 20 kHz, and the vibration energy causes the entire diaphragm (polymer composite piezoelectric body) to vibrate as one to reproduce sound. be. Therefore, the polymer composite piezoelectric body is required to have appropriate hardness in order to increase the transmission efficiency of vibration energy. Also, if the frequency characteristics of the speaker are smooth, the amount of change in sound quality when the lowest resonance frequency f 0 changes as the curvature changes becomes small. Therefore, the loss tangent of the polymer composite piezoelectric body is required to be moderately large.
（ｉ） 可撓性
例えば、携帯用として新聞や雑誌のように書類感覚で緩く撓めた状態で把持する場合、絶えず外部から、数Ｈｚ以下の比較的ゆっくりとした、大きな曲げ変形を受けることになる。この時、高分子複合圧電体が硬いと、その分大きな曲げ応力が発生し、高分子マトリックスと圧電体粒子との界面で亀裂が発生し、やがて破壊に繋がる恐れがある。従って、高分子複合圧電体には適度な柔らかさが求められる。また、歪みエネルギーを熱として外部へ拡散できれば応力を緩和することができる。従って、高分子複合圧電体の損失正接が適度に大きいことが求められる。
（ii） 音質
スピーカーは、２０Ｈｚ～２０ｋＨｚのオーディオ帯域の周波数で圧電体粒子を振動させ、その振動エネルギーによって振動板（高分子複合圧電体）全体が一体となって振動することで音が再生される。従って、振動エネルギーの伝達効率を高めるために高分子複合圧電体には適度な硬さが求められる。また、スピーカーの周波数特性が平滑であれば、曲率の変化に伴い最低共振周波数ｆ0が変化した際の音質の変化量も小さくなる。従って、高分子複合圧電体の損失正接は適度に大きいことが求められる。 Here, the polymer composite piezoelectric body (piezoelectric layer 26) preferably satisfies the following requirements. In the present invention, normal temperature is 0 to 50°C.
(i) 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. Moreover, stress can be relieved if strain energy can be diffused to the outside as heat. Therefore, it is required that the loss tangent of the polymer composite piezoelectric material is appropriately large.
(ii) Sound quality A speaker vibrates piezoelectric particles at frequencies in the audio band of 20 Hz to 20 kHz, and the vibration energy causes the entire diaphragm (polymer composite piezoelectric body) to vibrate as one to reproduce sound. be. Therefore, the polymer composite piezoelectric body is required to have appropriate hardness in order to increase the transmission efficiency of vibration energy. Also, if the frequency characteristics of the speaker are smooth, the amount of change in sound quality when the lowest resonance frequency f 0 changes as the curvature changes becomes small. Therefore, the loss tangent of the polymer composite piezoelectric body is required to be moderately large.
スピーカー用振動板の最低共振周波数ｆ0は、下記式で与えられるのは周知である。ここで、ｓは振動系のスチフネス、ｍは質量である。
このとき、圧電フィルムの湾曲程度すなわち湾曲部の曲率半径が大きくなるほど機械的なスチフネスｓが下がるため、最低共振周波数ｆ0は小さくなる。すなわち、圧電フィルムの曲率半径によってスピーカーの音質（音量、周波数特性）が変わることになる。 It is well known that the lowest resonance frequency f 0 of the speaker diaphragm is given by the following equation. where s is the stiffness of the vibration system and m is the mass.
At this time, as the degree of curvature of the piezoelectric film, that is, the radius of curvature of the curved portion increases, the mechanical stiffness s decreases, so the minimum resonance frequency f 0 decreases. That is, the sound quality (volume and frequency characteristics) of the speaker changes depending on the radius of curvature of the piezoelectric film.
このとき、圧電フィルムの湾曲程度すなわち湾曲部の曲率半径が大きくなるほど機械的なスチフネスｓが下がるため、最低共振周波数ｆ0は小さくなる。すなわち、圧電フィルムの曲率半径によってスピーカーの音質（音量、周波数特性）が変わることになる。 It is well known that the lowest resonance frequency f 0 of the speaker diaphragm is given by the following equation. where s is the stiffness of the vibration system and m is the mass.
At this time, as the degree of curvature of the piezoelectric film, that is, the radius of curvature of the curved portion increases, the mechanical stiffness s decreases, so the minimum resonance frequency f 0 decreases. That is, the sound quality (volume and frequency characteristics) of the speaker changes depending on the radius of curvature of the piezoelectric film.
以上をまとめると、高分子複合圧電体は、２０Ｈｚ～２０ｋＨｚの振動に対しては硬く、数Ｈｚ以下の振動に対しては柔らかく振る舞うことが求められる。また、高分子複合圧電体の損失正接は、２０ｋＨｚ以下の全ての周波数の振動に対して、適度に大きいことが求められる。
In summary, 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.
一般に、高分子固体は粘弾性緩和機構を有しており、温度上昇あるいは周波数の低下と共に大きなスケールの分子運動が貯蔵弾性率（ヤング率）の低下（緩和）あるいは損失弾性率の極大（吸収）として観測される。その中でも、非晶質領域の分子鎖のミクロブラウン運動によって引き起こされる緩和は、主分散と呼ばれ、非常に大きな緩和現象が見られる。この主分散が起きる温度がガラス転移点（Ｔｇ）であり、最も粘弾性緩和機構が顕著に現れる。
高分子複合圧電体（圧電体層２６）において、ガラス転移点が常温にある高分子材料、言い換えると、常温で粘弾性を有する高分子材料をマトリックスに用いることで、２０Ｈｚ～２０ｋＨｚの振動に対しては硬く、数Ｈｚ以下の遅い振動に対しては柔らかく振舞う高分子複合圧電体が実現する。特に、この振舞いが好適に発現する等の点で、周波数１Ｈｚでのガラス転移点Ｔｇが常温にある高分子材料を、高分子複合圧電体のマトリックスに用いるのが好ましい。 In general, 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.
In 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. This realizes a polymer composite piezoelectric material that is hard at first and behaves softly with respect to slow vibrations of several Hz or less. In particular, it is preferable to use a polymer material whose glass transition point Tg at a frequency of 1 Hz is at normal temperature for the matrix of the polymer composite piezoelectric material, because this behavior is preferably exhibited.
高分子複合圧電体（圧電体層２６）において、ガラス転移点が常温にある高分子材料、言い換えると、常温で粘弾性を有する高分子材料をマトリックスに用いることで、２０Ｈｚ～２０ｋＨｚの振動に対しては硬く、数Ｈｚ以下の遅い振動に対しては柔らかく振舞う高分子複合圧電体が実現する。特に、この振舞いが好適に発現する等の点で、周波数１Ｈｚでのガラス転移点Ｔｇが常温にある高分子材料を、高分子複合圧電体のマトリックスに用いるのが好ましい。 In general, 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.
In 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. This realizes a polymer composite piezoelectric material that is hard at first and behaves softly with respect to slow vibrations of several Hz or less. In particular, it is preferable to use a polymer material whose glass transition point Tg at a frequency of 1 Hz is at normal temperature for the matrix of the polymer composite piezoelectric material, because this behavior is preferably exhibited.
高分子マトリックス３８となる高分子材料は、常温において、動的粘弾性試験による周波数１Ｈｚにおける損失正接Ｔａｎδの極大値が、０．５以上であるのが好ましい。
これにより、高分子複合圧電体が外力によってゆっくりと曲げられた際に、最大曲げモーメント部における高分子マトリックス／圧電体粒子界面の応力集中が緩和され、高い可撓性が期待できる。 The polymer material that forms thepolymer matrix 38 preferably has a maximum loss tangent Tan δ of 0.5 or more at a frequency of 1 Hz in a dynamic viscoelasticity test at room temperature.
As a result, when the polymer composite piezoelectric body is slowly bent by an external force, stress concentration at the polymer matrix/piezoelectric particle interface at the maximum bending moment portion is alleviated, and high flexibility can be expected.
これにより、高分子複合圧電体が外力によってゆっくりと曲げられた際に、最大曲げモーメント部における高分子マトリックス／圧電体粒子界面の応力集中が緩和され、高い可撓性が期待できる。 The polymer material that forms the
As a result, when the polymer composite piezoelectric body is slowly bent by an external force, stress concentration at the polymer matrix/piezoelectric particle interface at the maximum bending moment portion is alleviated, and high flexibility can be expected.
また、高分子マトリックス３８となる高分子材料は、動的粘弾性測定による周波数１Ｈｚでの貯蔵弾性率（Ｅ’）が、０℃において１００ＭＰａ以上、５０℃において１０ＭＰａ以下であるのが好ましい。
これにより、高分子複合圧電体が外力によってゆっくりと曲げられた際に発生する曲げモーメントが低減できると同時に、２０Ｈｚ～２０ｋＨｚの音響振動に対しては硬く振る舞うことができる。 In addition, it is preferable that the storage elastic modulus (E') at a frequency of 1 Hz measured by dynamic viscoelasticity measurement of the polymer material forming thepolymer matrix 38 is 100 MPa or more at 0°C and 10 MPa or less at 50°C.
As a result, the bending moment generated when the polymeric composite piezoelectric body is slowly bent by an external force can be reduced, and at the same time, it can behave rigidly against acoustic vibrations of 20 Hz to 20 kHz.
これにより、高分子複合圧電体が外力によってゆっくりと曲げられた際に発生する曲げモーメントが低減できると同時に、２０Ｈｚ～２０ｋＨｚの音響振動に対しては硬く振る舞うことができる。 In addition, it is preferable that the storage elastic modulus (E') at a frequency of 1 Hz measured by dynamic viscoelasticity measurement of the polymer material forming the
As a result, the bending moment generated when the polymeric composite piezoelectric body is slowly bent by an external force can be reduced, and at the same time, it can behave rigidly against acoustic vibrations of 20 Hz to 20 kHz.
また、高分子マトリックス３８となる高分子材料は、比誘電率が２５℃において１０以上で有ると、より好適である。これにより、高分子複合圧電体に電圧を印加した際に、高分子マトリックス中の圧電体粒子にはより高い電界がかかるため、大きな変形量が期待できる。
しかしながら、その反面、良好な耐湿性の確保等を考慮すると、高分子材料は、比誘電率が２５℃において１０以下であるのも、好適である。 Further, it is more preferable that the polymer material that forms thepolymer matrix 38 has a dielectric constant of 10 or more at 25°C. As a result, when 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.
On the other hand, however, 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.
しかしながら、その反面、良好な耐湿性の確保等を考慮すると、高分子材料は、比誘電率が２５℃において１０以下であるのも、好適である。 Further, it is more preferable that the polymer material that forms the
On the other hand, however, 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.
このような条件を満たす高分子材料としては、シアノエチル化ポリビニルアルコール（シアノエチル化ＰＶＡ）、ポリ酢酸ビニル、ポリビニリデンクロライドコアクリロニトリル、ポリスチレン－ビニルポリイソプレンブロック共重合体、ポリビニルメチルケトン、および、ポリブチルメタクリレート等が好適に例示される。
また、これらの高分子材料としては、ハイブラー５１２７（クラレ社製）などの市販品も、好適に利用可能である。 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.
また、これらの高分子材料としては、ハイブラー５１２７（クラレ社製）などの市販品も、好適に利用可能である。 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.
高分子マトリックス３８を構成する高分子材料としては、シアノエチル基を有する高分子材料を用いるのが好ましく、シアノエチル化ＰＶＡを用いるのが特に好ましい。すなわち、圧電フィルム１２において、圧電体層２６は、高分子マトリックス３８として、シアノエチル基を有する高分子材料を用いるのが好ましく、シアノエチル化ＰＶＡを用いるのが特に好ましい。
以下の説明では、シアノエチル化ＰＶＡを代表とする上述の高分子材料を、まとめて『常温で粘弾性を有する高分子材料』とも言う。 As the polymer material constituting thepolymer matrix 38, it is preferable to use a polymer material having a cyanoethyl group, and it is particularly preferable to use cyanoethylated PVA. That is, in the piezoelectric film 12, the piezoelectric layer 26 preferably uses a polymer material having a cyanoethyl group as the polymer matrix 38, and more preferably uses cyanoethylated PVA.
In the following description, the above-mentioned polymeric materials represented by cyanoethylated PVA are collectively referred to as "polymeric materials having viscoelasticity at room temperature".
以下の説明では、シアノエチル化ＰＶＡを代表とする上述の高分子材料を、まとめて『常温で粘弾性を有する高分子材料』とも言う。 As the polymer material constituting the
In the following description, the above-mentioned polymeric materials represented by cyanoethylated PVA are collectively referred to as "polymeric materials having viscoelasticity at room temperature".
なお、これらの常温で粘弾性を有する高分子材料は、１種のみを用いてもよく、複数種を併用（混合）して用いてもよい。
These polymer materials having viscoelasticity at room temperature may be used alone or in combination (mixed).
圧電フィルム１２において、圧電体層２６の高分子マトリックス３８には、必要に応じて、複数の高分子材料を併用してもよい。
すなわち、高分子複合圧電体を構成する高分子マトリックス３８には、誘電特性や機械的特性の調節等を目的として、上述した常温で粘弾性を有する高分子材料に加え、必要に応じて、その他の誘電性高分子材料を添加しても良い。 In thepiezoelectric film 12, the polymer matrix 38 of the piezoelectric layer 26 may be made of a combination of multiple polymer materials, if necessary.
That is, for thepolymer 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.
すなわち、高分子複合圧電体を構成する高分子マトリックス３８には、誘電特性や機械的特性の調節等を目的として、上述した常温で粘弾性を有する高分子材料に加え、必要に応じて、その他の誘電性高分子材料を添加しても良い。 In the
That is, for the
添加可能な誘電性高分子材料としては、一例として、ポリフッ化ビニリデン、フッ化ビニリデン－テトラフルオロエチレン共重合体、フッ化ビニリデン－トリフルオロエチレン共重合体、ポリフッ化ビニリデン－トリフルオロエチレン共重合体およびポリフッ化ビニリデン－テトラフルオロエチレン共重合体等のフッ素系高分子、シアン化ビニリデン－酢酸ビニル共重合体、シアノエチルセルロース、シアノエチルヒドロキシサッカロース、シアノエチルヒドロキシセルロース、シアノエチルヒドロキシプルラン、シアノエチルメタクリレート、シアノエチルアクリレート、シアノエチルヒドロキシエチルセルロース、シアノエチルアミロース、シアノエチルヒドロキシプロピルセルロース、シアノエチルジヒドロキシプロピルセルロース、シアノエチルヒドロキシプロピルアミロース、シアノエチルポリアクリルアミド、シアノエチルポリアクリレート、シアノエチルプルラン、シアノエチルポリヒドロキシメチレン、シアノエチルグリシドールプルラン、シアノエチルサッカロースおよびシアノエチルソルビトール等のシアノ基またはシアノエチル基を有するポリマー、ならびに、ニトリルゴムおよびクロロプレンゴム等の合成ゴム等が例示される。
中でも、シアノエチル基を有する高分子材料は、好適に利用される。
また、圧電体層２６の高分子マトリックス３８において、これらの誘電性高分子材料は、１種に制限はされず、複数種を添加してもよい。 Examples of dielectric polymer materials that can be added include polyvinylidene fluoride, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, and polyvinylidene fluoride-trifluoroethylene copolymer. and 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, cyanoethylglycidolpullulan, cyanoethylsaccharose and cyanoethylsorbitol. Alternatively, polymers having cyanoethyl groups, and synthetic rubbers such as nitrile rubbers and chloroprene rubbers are exemplified.
Among them, polymer materials having cyanoethyl groups are preferably used.
Moreover, in thepolymer matrix 38 of the piezoelectric layer 26, these dielectric polymer materials are not limited to one type, and a plurality of types may be added.
中でも、シアノエチル基を有する高分子材料は、好適に利用される。
また、圧電体層２６の高分子マトリックス３８において、これらの誘電性高分子材料は、１種に制限はされず、複数種を添加してもよい。 Examples of dielectric polymer materials that can be added include polyvinylidene fluoride, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, and polyvinylidene fluoride-trifluoroethylene copolymer. and 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, cyanoethylglycidolpullulan, cyanoethylsaccharose and cyanoethylsorbitol. Alternatively, polymers having cyanoethyl groups, and synthetic rubbers such as nitrile rubbers and chloroprene rubbers are exemplified.
Among them, polymer materials having cyanoethyl groups are preferably used.
Moreover, in the
また、誘電性高分子材料以外にも、高分子マトリックス３８のガラス転移点Ｔｇを調節する目的で、塩化ビニル樹脂、ポリエチレン、ポリスチレン、メタクリル樹脂、ポリブテンおよびイソブチレン等の熱可塑性樹脂、ならびに、フェノール樹脂、尿素樹脂、メラミン樹脂、アルキド樹脂およびマイカ等の熱硬化性樹脂等を添加しても良い。
さらに、粘着性を向上する目的で、ロジンエステル、ロジン、テルペン、テルペンフェノール、および、石油樹脂等の粘着付与剤を添加しても良い。 In addition to dielectric polymer materials, 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 thepolymer matrix 38. , thermosetting resins such as urea resins, melamine resins, alkyd resins and mica may be added.
Furthermore, a tackifier such as rosin ester, rosin, terpene, terpene phenol, and petroleum resin may be added for the purpose of improving adhesiveness.
さらに、粘着性を向上する目的で、ロジンエステル、ロジン、テルペン、テルペンフェノール、および、石油樹脂等の粘着付与剤を添加しても良い。 In addition to dielectric polymer materials, 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
Furthermore, a tackifier such as rosin ester, rosin, terpene, terpene phenol, and petroleum resin may be added for the purpose of improving adhesiveness.
圧電体層２６の高分子マトリックス３８において、常温で粘弾性を有する高分子材料以外の高分子材料を添加する際の添加量には制限はないが、高分子マトリックス３８に占める割合で３０質量％以下とするのが好ましい。
これにより、高分子マトリックス３８における粘弾性緩和機構を損なうことなく、添加する高分子材料の特性を発現できるため、高誘電率化、耐熱性の向上、圧電体粒子４０や電極層との密着性向上等の点で好ましい結果を得ることができる。 In thepolymer matrix 38 of the piezoelectric layer 26, 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 thepolymer 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.
これにより、高分子マトリックス３８における粘弾性緩和機構を損なうことなく、添加する高分子材料の特性を発現できるため、高誘電率化、耐熱性の向上、圧電体粒子４０や電極層との密着性向上等の点で好ましい結果を得ることができる。 In the
As a result, the characteristics of the polymer material to be added can be expressed without impairing the viscoelastic relaxation mechanism in the
圧電体層２６となる高分子複合圧電体は、このような高分子マトリックスに、圧電体粒子４０を含むものである。圧電体粒子４０は、高分子マトリックスに分散されており、好ましくは、均一（略均一）に分散される。
圧電体粒子４０は、好ましくは、ペロブスカイト型またはウルツ鉱型の結晶構造を有するセラミックス粒子からなるものである。
圧電体粒子４０を構成するセラミックス粒子としては、例えば、チタン酸ジルコン酸鉛（ＰＺＴ）、チタン酸ジルコン酸ランタン酸鉛（ＰＬＺＴ）、チタン酸バリウム（ＢａＴｉＯ3）、酸化亜鉛（ＺｎＯ）、および、チタン酸バリウムとビスマスフェライト（ＢｉＦｅ3）との固溶体（ＢＦＢＴ）等が例示される。 The polymer composite piezoelectric material that forms thepiezoelectric 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).
Thepiezoelectric particles 40 are preferably ceramic particles having a perovskite or wurtzite crystal structure.
Examples of ceramic particles constituting thepiezoelectric 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.
圧電体粒子４０は、好ましくは、ペロブスカイト型またはウルツ鉱型の結晶構造を有するセラミックス粒子からなるものである。
圧電体粒子４０を構成するセラミックス粒子としては、例えば、チタン酸ジルコン酸鉛（ＰＺＴ）、チタン酸ジルコン酸ランタン酸鉛（ＰＬＺＴ）、チタン酸バリウム（ＢａＴｉＯ3）、酸化亜鉛（ＺｎＯ）、および、チタン酸バリウムとビスマスフェライト（ＢｉＦｅ3）との固溶体（ＢＦＢＴ）等が例示される。 The polymer composite piezoelectric material that forms the
The
Examples of ceramic particles constituting the
圧電体粒子４０の粒径は、圧電フィルム１２のサイズや用途に応じて、適宜、選択すれば良い。圧電体粒子４０の粒径は、１～１０μｍが好ましい。
圧電体粒子４０の粒径を上記範囲とすることにより、高い圧電特性とフレキシビリティとを両立できる等の点で好ましい結果を得ることができる。 The particle size of thepiezoelectric 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 μm.
By setting the particle size of thepiezoelectric particles 40 within the above range, favorable results can be obtained in terms of achieving both high piezoelectric characteristics and flexibility.
圧電体粒子４０の粒径を上記範囲とすることにより、高い圧電特性とフレキシビリティとを両立できる等の点で好ましい結果を得ることができる。 The particle size of the
By setting the particle size of the
圧電フィルム１２において、圧電体層２６中における高分子マトリックス３８と圧電体粒子４０との量比は、圧電フィルム１２の面方向の大きさや厚さ、圧電フィルム１２の用途、圧電フィルム１２に要求される特性等に応じて、適宜、設定すればよい。
圧電体層２６中における圧電体粒子４０の体積分率は、３０～８０％が好ましく、５０～８０％がより好ましい。
高分子マトリックス３８と圧電体粒子４０との量比を上記範囲とすることにより、高い圧電特性とフレキシビリティとを両立できる等の点で好ましい結果を得ることができる。 In thepiezoelectric film 12, 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 thepiezoelectric particles 40 in the piezoelectric layer 26 is preferably 30-80%, more preferably 50-80%.
By setting the amount ratio between thepolymer matrix 38 and the piezoelectric particles 40 within the above range, favorable results can be obtained in terms of achieving both high piezoelectric characteristics and flexibility.
圧電体層２６中における圧電体粒子４０の体積分率は、３０～８０％が好ましく、５０～８０％がより好ましい。
高分子マトリックス３８と圧電体粒子４０との量比を上記範囲とすることにより、高い圧電特性とフレキシビリティとを両立できる等の点で好ましい結果を得ることができる。 In the
The volume fraction of the
By setting the amount ratio between the
また、圧電フィルム１２において、圧電体層２６の厚さには制限はなく、圧電フィルム１２のサイズ、圧電フィルム１２の用途、圧電フィルム１２に要求される特性等に応じて、適宜、設定すればよい。
圧電体層２６の厚さは、８～３００μｍが好ましく、８～２００μｍがより好ましく、１０～１５０μｍがさらに好ましく、１５～１００μｍが特に好ましい。
圧電体層２６の厚さを、上記範囲とすることにより、剛性の確保と適度な柔軟性との両立等の点で好ましい結果を得ることができる。 In thepiezoelectric film 12, 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 thepiezoelectric layer 26 is preferably 8-300 μm, more preferably 8-200 μm, still more preferably 10-150 μm, particularly preferably 15-100 μm.
By setting the thickness of thepiezoelectric layer 26 within the above range, favorable results can be obtained in terms of ensuring both rigidity and appropriate flexibility.
圧電体層２６の厚さは、８～３００μｍが好ましく、８～２００μｍがより好ましく、１０～１５０μｍがさらに好ましく、１５～１００μｍが特に好ましい。
圧電体層２６の厚さを、上記範囲とすることにより、剛性の確保と適度な柔軟性との両立等の点で好ましい結果を得ることができる。 In the
The thickness of the
By setting the thickness of the
圧電体層２６は、厚さ方向に分極処理（ポーリング）されているのが好ましい。分極処理に関しては、後に詳述する。
The piezoelectric layer 26 is preferably polarized (poled) in the thickness direction. The polarization treatment will be detailed later.
なお、圧電フィルム１２において、圧電体層２６は、上述したような、シアノエチル化ＰＶＡのような常温で粘弾性を有する高分子材料からなる高分子マトリックス３８に、圧電体粒子４０を含む高分子複合圧電体に制限はされない。
すなわち、圧電フィルム１２において、圧電体層は、公知の圧電体層が、各種、利用可能である。 In thepiezoelectric film 12, 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. There is no limitation to piezoelectric bodies.
That is, in thepiezoelectric film 12, various known piezoelectric layers can be used for the piezoelectric layer.
すなわち、圧電フィルム１２において、圧電体層は、公知の圧電体層が、各種、利用可能である。 In the
That is, in the
一例として、上述したポリフッ化ビニリデン、フッ化ビニリデン－テトラフルオロエチレン共重合体およびフッ化ビニリデン－トリフルオロエチレン共重合体等の誘電性高分子材料を含むマトリックスに同様の圧電体粒子４０を含む高分子複合圧電体、ポリフッ化ビニリデンからなる圧電体層、ポリフッ化ビニリデン以外のフッ素樹脂からなる圧電体層、ならびに、ポリＬ乳酸からなるフィルムとポリＤ乳酸からなるフィルムとを積層した圧電体層等も利用可能である。
しかしながら、上述のように、２０Ｈｚ～２０ｋＨｚの振動に対しては硬く、数Ｈｚ以下の遅い振動に対しては柔らかく振舞うことができ、優れた音響特性が得られる、可撓性に優れる等の点で、上述したシアノエチル化ＰＶＡのような常温で粘弾性を有する高分子材料からなる高分子マトリックス３８に、圧電体粒子４０を含む高分子複合圧電体が、好適に利用される。 As an example, a high-performance dielectric material containing similarpiezoelectric 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.
However, as described above, it is hard against vibrations of 20 Hz to 20 kHz, and can behave softly against slow vibrations of several Hz or less, and has excellent acoustic characteristics and excellent flexibility. A polymer composite piezoelectric body containingpiezoelectric particles 40 in a polymer matrix 38 made of a polymer material having viscoelasticity at room temperature, such as the cyanoethylated PVA described above, is preferably used.
しかしながら、上述のように、２０Ｈｚ～２０ｋＨｚの振動に対しては硬く、数Ｈｚ以下の遅い振動に対しては柔らかく振舞うことができ、優れた音響特性が得られる、可撓性に優れる等の点で、上述したシアノエチル化ＰＶＡのような常温で粘弾性を有する高分子材料からなる高分子マトリックス３８に、圧電体粒子４０を含む高分子複合圧電体が、好適に利用される。 As an example, a high-performance dielectric material containing similar
However, as described above, it is hard against vibrations of 20 Hz to 20 kHz, and can behave softly against slow vibrations of several Hz or less, and has excellent acoustic characteristics and excellent flexibility. A polymer composite piezoelectric body containing
図４に示す圧電フィルム１２は、このような圧電体層２６の一面に、第２電極層３０を有し、第２電極層３０の表面に第２保護層３４を有し、圧電体層２６の他方の面に、第１電極層２８を有し、第１電極層２８の表面に第１保護層３２を有してなる構成を有する。圧電フィルム１２では、第１電極層２８と第２電極層３０とが電極対を形成する。
言い換えれば、圧電フィルム１２を構成する積層フィルムは、圧電体層２６の両面を電極対、すなわち、第１電極層２８および第２電極層３０で挟持し、さらに、第１保護層３２および第２保護層３４で挟持してなる構成を有する。
このように、第１電極層２８および第２電極層３０で挾持された領域は、印加された電圧に応じて駆動される。 Thepiezoelectric 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 . In the piezoelectric film 12, the first electrode layer 28 and the second electrode layer 30 form an electrode pair.
In other words, in the laminated film that constitutes thepiezoelectric film 12, 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 .
Thus, the regions sandwiched by thefirst electrode layer 28 and the second electrode layer 30 are driven according to the applied voltage.
言い換えれば、圧電フィルム１２を構成する積層フィルムは、圧電体層２６の両面を電極対、すなわち、第１電極層２８および第２電極層３０で挟持し、さらに、第１保護層３２および第２保護層３４で挟持してなる構成を有する。
このように、第１電極層２８および第２電極層３０で挾持された領域は、印加された電圧に応じて駆動される。 The
In other words, in the laminated film that constitutes the
Thus, the regions sandwiched by the
圧電フィルム１２は、これらの層に加えて、例えば、電極層と圧電体層２６とを貼着するための貼着層、および、電極層と保護層とを貼着するための貼着層を有してもよい。
貼着剤は、接着剤でも粘着剤でもよい。また、貼着剤は、圧電体層２６から圧電体粒子４０を除いた高分子材料すなわち高分子マトリックス３８と同じ材料も、好適に利用可能である。なお、貼着層は、第１電極層２８側および第２電極層３０側の両方に有してもよく、第１電極層２８側および第２電極層３０側の一方のみに有してもよい。 In addition to these layers, thepiezoelectric 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. Also, as the adhesive, a polymer material obtained by removing thepiezoelectric 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.
貼着剤は、接着剤でも粘着剤でもよい。また、貼着剤は、圧電体層２６から圧電体粒子４０を除いた高分子材料すなわち高分子マトリックス３８と同じ材料も、好適に利用可能である。なお、貼着層は、第１電極層２８側および第２電極層３０側の両方に有してもよく、第１電極層２８側および第２電極層３０側の一方のみに有してもよい。 In addition to these layers, the
The adhesive may be an adhesive or an adhesive. Also, as the adhesive, a polymer material obtained by removing the
圧電フィルム１２において、第１保護層３２および第２保護層３４は、第１電極層２８および第２電極層３０を被覆すると共に、圧電体層２６に適度な剛性と機械的強度を付与する役目を担っている。すなわち、圧電フィルム１２において、高分子マトリックス３８と圧電体粒子４０とを含む圧電体層２６は、ゆっくりとした曲げ変形に対しては、非常に優れた可撓性を示す一方で、用途によっては、剛性や機械的強度が不足する場合がある。圧電フィルム１２は、それを補うために第１保護層３２および第２保護層３４が設けられる。
第１保護層３２と第２保護層３４とは、配置位置が異なるのみで、構成は同じである。従って、以下の説明においては、第１保護層３２および第２保護層３４を区別する必要がない場合には、両部材をまとめて、保護層ともいう。 In thepiezoelectric film 12, 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 firstprotective 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.
第１保護層３２と第２保護層３４とは、配置位置が異なるのみで、構成は同じである。従って、以下の説明においては、第１保護層３２および第２保護層３４を区別する必要がない場合には、両部材をまとめて、保護層ともいう。 In the
The first
保護層には、制限はなく、各種のシート状物が利用可能であり、一例として、各種の樹脂フィルムが好適に例示される。中でも、優れた機械的特性および耐熱性を有するなどの理由により、ポリエチレンテレフタレート（ＰＥＴ）、ポリプロピレン（ＰＰ）、ポリスチレン（ＰＳ）、ポリカーボネート（ＰＣ）、ポリフェニレンサルファイト（ＰＰＳ）、ポリメチルメタクリレート（ＰＭＭＡ）、ポリエーテルイミド（ＰＥＩ）、ポリイミド（ＰＩ）、ポリアミド（ＰＡ）、ポリエチレンナフタレート（ＰＥＮ）、トリアセチルセルロース（ＴＡＣ）、および、環状オレフィン系樹脂等からなる樹脂フィルムが好適に利用される。
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. .
保護層の厚さにも、制限は無い。また、第１保護層３２および第２保護層３４の厚さは、基本的に同じであるが、異なってもよい。
保護層の剛性が高過ぎると、圧電体層２６の伸縮を拘束するばかりか、可撓性も損なわれる。そのため、機械的強度やシート状物としての良好なハンドリング性が要求される場合を除けば、保護層は、薄いほど有利である。 The thickness of the protective layer is also not limited. Also, the thicknesses of the firstprotective 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 thepiezoelectric 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.
保護層の剛性が高過ぎると、圧電体層２６の伸縮を拘束するばかりか、可撓性も損なわれる。そのため、機械的強度やシート状物としての良好なハンドリング性が要求される場合を除けば、保護層は、薄いほど有利である。 The thickness of the protective layer is also not limited. Also, the thicknesses of the first
If the rigidity of the protective layer is too high, it not only restricts expansion and contraction of the
第１保護層３２および第２保護層３４の厚さが、それぞれ、圧電体層２６の厚さの２倍以下であれば、剛性の確保と適度な柔軟性との両立等の点で好ましい結果を得られる。
例えば、圧電体層２６の厚さが５０μｍで第１保護層３２および第２保護層３４がＰＥＴからなる場合、第１保護層３２および第２保護層３４の厚さはそれぞれ、１００μｍ以下が好ましく、５０μｍ以下がより好ましく、２５μｍ以下がさらに好ましい。 If the thickness of each of the firstprotective 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.
For example, when the thickness of thepiezoelectric layer 26 is 50 μm 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 μm or less. , 50 μm or less, and even more preferably 25 μm or less.
例えば、圧電体層２６の厚さが５０μｍで第１保護層３２および第２保護層３４がＰＥＴからなる場合、第１保護層３２および第２保護層３４の厚さはそれぞれ、１００μｍ以下が好ましく、５０μｍ以下がより好ましく、２５μｍ以下がさらに好ましい。 If the thickness of each of the first
For example, when the thickness of the
なお、本発明において、第１保護層３２および第２保護層３４は、好ましい態様として用いられるものであり、必須の構成要件ではない。従って、圧電フィルム１２は、第１保護層３２のみを有するものでも、第２保護層３４のみを有するものでも、保護層を有さないものでもよい。
しかしながら、圧電フィルム１２の機械的強度、電極層の保護性等を考慮すると、圧電フィルムは、少なくとも１層の保護層を有するのが好ましく、図示例のように、両電極層を覆うように、２層の保護層を有するのがより好ましい。 In addition, in this invention, the 1stprotective layer 32 and the 2nd protective layer 34 are used as a preferable aspect, and are not essential components. Therefore, the piezoelectric film 12 may have only the first protective layer 32, only the second protective layer 34, or no protective layer.
However, considering the mechanical strength of thepiezoelectric film 12, the protection of the electrode layers, etc., the piezoelectric film preferably has at least one protective layer. More preferably, it has two protective layers.
しかしながら、圧電フィルム１２の機械的強度、電極層の保護性等を考慮すると、圧電フィルムは、少なくとも１層の保護層を有するのが好ましく、図示例のように、両電極層を覆うように、２層の保護層を有するのがより好ましい。 In addition, in this invention, the 1st
However, considering the mechanical strength of the
圧電フィルム１２において、圧電体層２６と第１保護層３２との間には第１電極層２８が、圧電体層２６と第２保護層３４との間には第２電極層３０が、それぞれ設けられる。第１電極層２８および第２電極層３０は、圧電体層２６に電圧を印加するためのものである。電極層から圧電体層２６への電圧の印加によって、圧電フィルム１２が伸縮する。
In the piezoelectric film 12, 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.
第１電極層２８および第２電極層３０は、位置が異なる以外は、基本的に同じものである。従って、以下の説明においては、第１電極層２８と第２電極層３０とを区別する必要がない場合には、両部材をまとめて、電極層ともいう。
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.
圧電フィルムにおいて、電極層の形成材料には制限はなく、各種の導電体が利用可能である。具体的には、炭素、パラジウム、鉄、錫、アルミニウム、ニッケル、白金、金、銀、銅、クロム、モリブデン、これらの合金、酸化インジウムスズ、および、ＰＥＤＯＴ／ＰＰＳ（ポリエチレンジオキシチオフェン－ポリスチレンスルホン酸）などの導電性高分子等が例示される。
中でも、銅、アルミニウム、金、銀、白金、および、酸化インジウムスズは、好適に例示される。その中でも、導電性、コストおよび可撓性等の観点から銅がより好ましい。 In the piezoelectric film, 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.
中でも、銅、アルミニウム、金、銀、白金、および、酸化インジウムスズは、好適に例示される。その中でも、導電性、コストおよび可撓性等の観点から銅がより好ましい。 In the piezoelectric film, 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.
また、電極層の形成方法にも制限はなく、真空蒸着およびスパッタリング等の気相堆積法（真空成膜法）やめっきによる成膜や、上記材料で形成された箔を貼着する方法、塗布する方法等、公知の方法が、各種、利用可能である。
中でも特に、圧電フィルム１２の可撓性が確保できる等の理由で、真空蒸着によって成膜された銅やアルミニウムの薄膜は、電極層として、好適に利用される。その中でも特に、真空蒸着による銅の薄膜は、好適に利用される。 In addition, 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. Various known methods such as the method of
In particular, a thin film of copper or aluminum formed by vacuum deposition is preferably used as the electrode layer because the flexibility of thepiezoelectric film 12 can be ensured. Among them, a copper thin film formed by vacuum deposition is particularly preferably used.
中でも特に、圧電フィルム１２の可撓性が確保できる等の理由で、真空蒸着によって成膜された銅やアルミニウムの薄膜は、電極層として、好適に利用される。その中でも特に、真空蒸着による銅の薄膜は、好適に利用される。 In addition, 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. Various known methods such as the method of
In particular, a thin film of copper or aluminum formed by vacuum deposition is preferably used as the electrode layer because the flexibility of the
第１電極層２８および第２電極層３０の厚さには、制限はない。また、第１電極層２８および第２電極層３０の厚さは、基本的に同じであるが、異なってもよい。
ここで、上述した保護層と同様に、電極層の剛性が高過ぎると、圧電体層２６の伸縮を拘束するばかりか、可撓性も損なわれる。そのため、電極層は、電気抵抗が高くなり過ぎない範囲であれば、薄いほど有利である。 The thicknesses of thefirst 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.
Here, as with the protective layer described above, if the rigidity of the electrode layer is too high, not only will the expansion and contraction of thepiezoelectric 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.
ここで、上述した保護層と同様に、電極層の剛性が高過ぎると、圧電体層２６の伸縮を拘束するばかりか、可撓性も損なわれる。そのため、電極層は、電気抵抗が高くなり過ぎない範囲であれば、薄いほど有利である。 The thicknesses of the
Here, as with the protective layer described above, if the rigidity of the electrode layer is too high, not only will the expansion and contraction of the
圧電フィルム１２では、電極層の厚さとヤング率との積が、保護層の厚さとヤング率との積を下回れば、可撓性を大きく損なうことがないため、好適である。
例えば、第１保護層３２および第２保護層３４がＰＥＴで、第１電極層２８および第２電極層３０が銅である場合を例示する。この際においては、ＰＥＴのヤング率が約６．２ＧＰａで、銅のヤング率が約１３０ＧＰａである。従って、保護層の厚さが２５μｍだとすると、電極層の厚さは、１．２μｍ以下が好ましく、０．３μｍ以下がより好ましく、中でも０．１μｍ以下とするのが好ましい。 In thepiezoelectric film 12, if the product of the thickness of the electrode layer and the Young's modulus is less than the product of the thickness of the protective layer and the Young's modulus, the flexibility is not greatly impaired, which is preferable.
For example, the firstprotective 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. In this case, 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 μm, the thickness of the electrode layer is preferably 1.2 μm or less, more preferably 0.3 μm or less, and most preferably 0.1 μm or less.
例えば、第１保護層３２および第２保護層３４がＰＥＴで、第１電極層２８および第２電極層３０が銅である場合を例示する。この際においては、ＰＥＴのヤング率が約６．２ＧＰａで、銅のヤング率が約１３０ＧＰａである。従って、保護層の厚さが２５μｍだとすると、電極層の厚さは、１．２μｍ以下が好ましく、０．３μｍ以下がより好ましく、中でも０．１μｍ以下とするのが好ましい。 In the
For example, the first
圧電フィルム１２は、圧電体層２６を第１電極層２８および第２電極層３０で挟持し、さらに、この積層体を第１保護層３２および第２保護層３４で挟持した構成を有する。
このような圧電フィルム１２は、動的粘弾性測定による周波数１Ｈｚでの損失正接（Ｔａｎδ）が０．１以上となる極大値が常温に存在するのが好ましい。
これにより、圧電フィルム１２が外部から数Ｈｚ以下の比較的ゆっくりとした、大きな曲げ変形を受けたとしても、歪みエネルギーを効果的に熱として外部へ拡散できるため、高分子マトリックスと圧電体粒子との界面で亀裂が発生するのを防ぐことができる。 Thepiezoelectric 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 .
In such apiezoelectric film 12, it is preferable that 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.
As a result, even if thepiezoelectric film 12 is subjected to a relatively slow and large bending deformation of several Hz or less from the outside, the strain energy can be effectively diffused to the outside as heat. It is possible to prevent cracks from occurring at the interface of
このような圧電フィルム１２は、動的粘弾性測定による周波数１Ｈｚでの損失正接（Ｔａｎδ）が０．１以上となる極大値が常温に存在するのが好ましい。
これにより、圧電フィルム１２が外部から数Ｈｚ以下の比較的ゆっくりとした、大きな曲げ変形を受けたとしても、歪みエネルギーを効果的に熱として外部へ拡散できるため、高分子マトリックスと圧電体粒子との界面で亀裂が発生するのを防ぐことができる。 The
In such a
As a result, even if the
圧電フィルム１２は、動的粘弾性測定による周波数１Ｈｚでの貯蔵弾性率（Ｅ’）が、０℃において１０～３０ＧＰａ、５０℃において１～１０ＧＰａであるのが好ましい。
これにより、常温で圧電フィルム１２が貯蔵弾性率（Ｅ’）に大きな周波数分散を有することができる。すなわち、２０Ｈｚ～２０ｋＨｚの振動に対しては硬く、数Ｈｚ以下の振動に対しては柔らかく振る舞うことができる。 Thepiezoelectric 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, thepiezoelectric 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.
これにより、常温で圧電フィルム１２が貯蔵弾性率（Ｅ’）に大きな周波数分散を有することができる。すなわち、２０Ｈｚ～２０ｋＨｚの振動に対しては硬く、数Ｈｚ以下の振動に対しては柔らかく振る舞うことができる。 The
Accordingly, the
また、圧電フィルム１２は、厚さと動的粘弾性測定による周波数１Ｈｚでの貯蔵弾性率（Ｅ’）との積が、０℃において１．０×１０6～２．０×１０6Ｎ／ｍ、５０℃において１．０×１０5～１．０×１０6Ｎ／ｍであるのが好ましい。
これにより、圧電フィルム１２が可撓性および音響特性を損なわない範囲で、適度な剛性と機械的強度を備えることができる。 In addition, thepiezoelectric 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.
As a result, thepiezoelectric film 12 can have appropriate rigidity and mechanical strength within a range that does not impair flexibility and acoustic properties.
これにより、圧電フィルム１２が可撓性および音響特性を損なわない範囲で、適度な剛性と機械的強度を備えることができる。 In addition, the
As a result, the
さらに、圧電フィルム１２は、動的粘弾性測定から得られたマスターカーブにおいて、２５℃、周波数１ｋＨｚにおける損失正接（Ｔａｎδ）が、０．０５以上であるのが好ましい。
Furthermore, the piezoelectric film 12 preferably has a loss tangent (Tan δ) of 0.05 or more at 25°C and a frequency of 1 kHz in a master curve obtained from dynamic viscoelasticity measurement.
以下、図５～図７を参照して、圧電フィルム１２の製造方法の一例を説明する。
まず、図５に概念的に示す、第２保護層３４の表面に第２電極層３０が形成されたシート状物４２ｂを準備する。さらに、図７に概念的に示す、第１保護層３２の表面に第１電極層２８が形成されたシート状物４２ａを準備する。 An example of a method for manufacturing thepiezoelectric film 12 will be described below with reference to FIGS. 5 to 7. FIG.
First, asheet 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.
まず、図５に概念的に示す、第２保護層３４の表面に第２電極層３０が形成されたシート状物４２ｂを準備する。さらに、図７に概念的に示す、第１保護層３２の表面に第１電極層２８が形成されたシート状物４２ａを準備する。 An example of a method for manufacturing the
First, a
シート状物４２ｂは、第２保護層３４の表面に、真空蒸着、スパッタリング、めっき等によって第２電極層３０として銅薄膜等を形成して、作製すればよい。同様に、シート状物４２ａは、第１保護層３２の表面に、真空蒸着、スパッタリング、めっき等によって第１電極層２８として銅薄膜等を形成して、作製すればよい。
あるいは、保護層の上に銅薄膜等が形成された市販品をシート状物を、シート状物４２ｂおよび／またはシート状物４２ａとして利用してもよい。
シート状物４２ｂおよびシート状物４２ａは、同じものでも、異なるものでもよい。 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. Similarly, 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.
Alternatively, a commercially available sheet having a copper thin film or the like formed on a protective layer may be used as thesheet 42b and/or the sheet 42a.
Thesheet 42b and the sheet 42a may be the same or different.
あるいは、保護層の上に銅薄膜等が形成された市販品をシート状物を、シート状物４２ｂおよび／またはシート状物４２ａとして利用してもよい。
シート状物４２ｂおよびシート状物４２ａは、同じものでも、異なるものでもよい。 The sheet-
Alternatively, a commercially available sheet having a copper thin film or the like formed on a protective layer may be used as the
The
なお、保護層が非常に薄く、ハンドリング性が悪い時などは、必要に応じて、セパレータ（仮支持体）付きの保護層を用いても良い。なお、セパレータとしては、厚さ２５～１００μｍのＰＥＴ等を用いることができる。セパレータは、電極層および保護層の熱圧着後、取り除けばよい。
In addition, when the protective layer is very thin and the handling property is poor, a protective layer with a separator (temporary support) may be used as necessary. As the separator, PET or the like having a thickness of 25 to 100 μm can be used. The separator may be removed after the electrode layer and protective layer are thermocompression bonded.
次いで、図６に概念的に示すように、シート状物４２ｂの第２電極層３０上に、圧電体層２６を形成して、シート状物４２ｂと圧電体層２６とを積層した積層体４６を作製する。
Next, as conceptually shown in FIG. 6, 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.
圧電体層２６は、圧電体層２６に応じた公知の方法で形成すればよい。
例えば、図４に示す、高分子マトリックス３８に圧電体粒子４０を分散してなる圧電体層（高分子複合圧電体層）であれば、一例として、以下のように作製する。
まず、有機溶媒に、上述したシアノエチル化ＰＶＡ等の高分子材料を溶解し、さらに、ＰＺＴ粒子等の圧電体粒子４０を添加し、攪拌して塗料を調製する。有機溶媒には制限はなく、ジメチルホルムアミド（ＤＭＦ）、メチルエチルケトン、および、シクロヘキサノン等の各種の有機溶媒が利用可能である。
シート状物４２ｂを準備し、かつ、塗料を調製したら、この塗料をシート状物４２ｂにキャスティング（塗布）して、有機溶媒を蒸発して乾燥する。これにより、図６に示すように、第２保護層３４の上に第２電極層３０を有し、第２電極層３０の上に圧電体層２６を積層してなる積層体４６を作製する。 Thepiezoelectric layer 26 may be formed by a known method suitable for the piezoelectric layer 26 .
For example, a piezoelectric layer (polymer composite piezoelectric layer) in whichpiezoelectric 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, andpiezoelectric 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.
After thesheet 42b is prepared and the paint is prepared, the paint is cast (applied) on the sheet 42b and dried by evaporating the organic solvent. As a result, as shown in FIG. 6, a laminate 46 having the second electrode layer 30 on the second protective layer 34 and the piezoelectric layer 26 laminated on the second electrode layer 30 is produced. .
例えば、図４に示す、高分子マトリックス３８に圧電体粒子４０を分散してなる圧電体層（高分子複合圧電体層）であれば、一例として、以下のように作製する。
まず、有機溶媒に、上述したシアノエチル化ＰＶＡ等の高分子材料を溶解し、さらに、ＰＺＴ粒子等の圧電体粒子４０を添加し、攪拌して塗料を調製する。有機溶媒には制限はなく、ジメチルホルムアミド（ＤＭＦ）、メチルエチルケトン、および、シクロヘキサノン等の各種の有機溶媒が利用可能である。
シート状物４２ｂを準備し、かつ、塗料を調製したら、この塗料をシート状物４２ｂにキャスティング（塗布）して、有機溶媒を蒸発して乾燥する。これにより、図６に示すように、第２保護層３４の上に第２電極層３０を有し、第２電極層３０の上に圧電体層２６を積層してなる積層体４６を作製する。 The
For example, a piezoelectric layer (polymer composite piezoelectric layer) in which
First, a polymer material such as cyanoethylated PVA is dissolved in an organic solvent, and
After the
塗料のキャスティング方法には制限はなく、バーコーター、スライドコーターおよびドクターナイフ等の公知の方法（塗布装置）が、全て、利用可能である。
あるいは高分子材料が加熱溶融可能な物であれば、高分子材料を加熱溶融して、これに圧電体粒子４０を添加してなる溶融物を作製し、押し出し成形等によって、図５に示すシート状物４２ｂの上にシート状に押し出し、冷却することにより、図６に示すような、積層体４６を作製してもよい。 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.
Alternatively, if the polymer material is heat-meltable, the polymer material is heat-melted and thepiezoelectric 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.
あるいは高分子材料が加熱溶融可能な物であれば、高分子材料を加熱溶融して、これに圧電体粒子４０を添加してなる溶融物を作製し、押し出し成形等によって、図５に示すシート状物４２ｂの上にシート状に押し出し、冷却することにより、図６に示すような、積層体４６を作製してもよい。 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.
Alternatively, if the polymer material is heat-meltable, the polymer material is heat-melted and the
なお、上述のように、圧電体層２６において、高分子マトリックス３８には、常温で粘弾性を有する高分子材料以外にも、ＰＶＤＦ等の高分子圧電材料を添加しても良い。
高分子マトリックス３８に、これらの高分子圧電材料を添加する際には、上記塗料に添加する高分子圧電材料を溶解すればよい。あるいは、加熱溶融した常温で粘弾性を有する高分子材料に、添加する高分子圧電材料を添加して加熱溶融すればよい。 As described above, in thepiezoelectric layer 26, 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.
When these polymeric piezoelectric materials are added to thepolymeric matrix 38, the polymeric piezoelectric materials to be added to the paint may be dissolved. Alternatively, 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.
高分子マトリックス３８に、これらの高分子圧電材料を添加する際には、上記塗料に添加する高分子圧電材料を溶解すればよい。あるいは、加熱溶融した常温で粘弾性を有する高分子材料に、添加する高分子圧電材料を添加して加熱溶融すればよい。 As described above, in the
When these polymeric piezoelectric materials are added to the
圧電体層２６を形成したら、必要に応じて、カレンダー処理を行ってもよい。カレンダー処理は、１回でもよく、複数回、行ってもよい。
周知のように、カレンダー処理とは、加熱プレス、加熱ローラおよび加熱ローラ対等によって、被処理面を加熱しつつ押圧して、平坦化等を施す処理である。 After thepiezoelectric 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.
周知のように、カレンダー処理とは、加熱プレス、加熱ローラおよび加熱ローラ対等によって、被処理面を加熱しつつ押圧して、平坦化等を施す処理である。 After the
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.
また、第２保護層３４の上に第２電極層３０を有し、第２電極層３０の上に圧電体層２６を形成してなる積層体４６の圧電体層２６に、分極処理（ポーリング）を行う。
圧電体層２６の分極処理の方法には制限はなく、公知の方法が利用可能である。例えば、分極処理を行う対象に、直接、直流電界を印加する、電界ポーリングが例示される。なお、電界ポーリングを行う場合には、分極処理の前に、第１電極層２８を形成して、第１電極層２８および第２電極層３０を利用して、電界ポーリング処理を行ってもよい。
また、圧電フィルム１２を製造する際には、分極処理は、圧電体層２６の面方向ではなく、厚さ方向に分極を行うのが好ましい。 Further, thepiezoelectric 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 thepiezoelectric layer 26 is not limited, and known methods can be used. For example, electric field poling, in which a DC electric field is directly applied to an object to be polarized, is exemplified. When electric field poling is performed, 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. .
When manufacturing thepiezoelectric film 12, it is preferable to polarize the piezoelectric layer 26 not in the plane direction but in the thickness direction.
圧電体層２６の分極処理の方法には制限はなく、公知の方法が利用可能である。例えば、分極処理を行う対象に、直接、直流電界を印加する、電界ポーリングが例示される。なお、電界ポーリングを行う場合には、分極処理の前に、第１電極層２８を形成して、第１電極層２８および第２電極層３０を利用して、電界ポーリング処理を行ってもよい。
また、圧電フィルム１２を製造する際には、分極処理は、圧電体層２６の面方向ではなく、厚さ方向に分極を行うのが好ましい。 Further, the
The method of polarization treatment of the
When manufacturing the
次いで、図７に概念的に示すように、積層体４６の圧電体層２６側に、先に準備したシート状物４２ａを、第１電極層２８を圧電体層２６に向けて積層する。
さらに、この積層体を、第１保護層３２および第２保護層３４を挟持するようにして、加熱プレス装置および加熱ローラ等を用いて熱圧着して、積層体４６とシート状物４２ａとを貼り合わせる。
これにより、圧電体層２６、圧電体層２６の両面に設けられる第１電極層２８および第２電極層３０、ならびに、電極層の表面に形成される第１保護層３２および第２保護層３４からなる圧電フィルム１２を作製する。 Next, as conceptually shown in FIG. 7, the previouslyprepared 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. Next, as shown in FIG.
Furthermore, this laminate is thermocompression bonded by using a hot press device, a heating roller, etc., with the firstprotective 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.
As a result, thepiezoelectric 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 A piezoelectric film 12 made of
さらに、この積層体を、第１保護層３２および第２保護層３４を挟持するようにして、加熱プレス装置および加熱ローラ等を用いて熱圧着して、積層体４６とシート状物４２ａとを貼り合わせる。
これにより、圧電体層２６、圧電体層２６の両面に設けられる第１電極層２８および第２電極層３０、ならびに、電極層の表面に形成される第１保護層３２および第２保護層３４からなる圧電フィルム１２を作製する。 Next, as conceptually shown in FIG. 7, the previously
Furthermore, this laminate is thermocompression bonded by using a hot press device, a heating roller, etc., with the first
As a result, the
このように作製される圧電フィルム１２は、面方向ではなく厚さ方向に分極されており、かつ、分極処理後に延伸処理をしなくても大きな圧電特性が得られる。そのため、圧電フィルム１２は、圧電特性に面内異方性がなく、駆動電圧を印加すると、面方向では全方向に等方的に伸縮する。
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.
上述のように、圧電素子１０は、圧電フィルム１２を折り返すことによって、複数層を積層し、かつ、積層されて隣接する圧電フィルム１２同士を、貼着層２０によって貼着してなるものである。
ここで、本発明の圧電素子１０は、図１に示すように、圧電素子１０の最厚部Ｍにおける貼着層の厚さをｔ、圧電素子１０の最厚部Ｍと稜線との最短距離をＬとした際に、『Ｌ≧５０＊ｔ』を満たす。上述のように、稜線とは、圧電フィルム１２の折り返し部の端部（外側端部）の頂部が形成する、折り返し線である。
なお、本発明において、圧電素子１０の厚さとは、圧電フィルム１２の積層方向の厚さである。従って、圧電素子１０の最厚部Ｍとは、圧電フィルム１２の積層方向における、最も厚い部分である。また、後述するが、本発明において、圧電素子１０の最厚部Ｍとは、圧電フィルム１２の折り返し方向における、最も圧電素子１０が厚い部分である。 As described above, thepiezoelectric 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 . .
Here, in thepiezoelectric element 10 of the present invention, as shown in FIG. is L, "L≧50*t" is satisfied. As described above, the ridgeline is a folding line formed by the apex of the folding end (outer end) of the piezoelectric film 12 .
In the present invention, the thickness of thepiezoelectric element 10 is the thickness of the piezoelectric film 12 in the stacking direction. Therefore, 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 .
ここで、本発明の圧電素子１０は、図１に示すように、圧電素子１０の最厚部Ｍにおける貼着層の厚さをｔ、圧電素子１０の最厚部Ｍと稜線との最短距離をＬとした際に、『Ｌ≧５０＊ｔ』を満たす。上述のように、稜線とは、圧電フィルム１２の折り返し部の端部（外側端部）の頂部が形成する、折り返し線である。
なお、本発明において、圧電素子１０の厚さとは、圧電フィルム１２の積層方向の厚さである。従って、圧電素子１０の最厚部Ｍとは、圧電フィルム１２の積層方向における、最も厚い部分である。また、後述するが、本発明において、圧電素子１０の最厚部Ｍとは、圧電フィルム１２の折り返し方向における、最も圧電素子１０が厚い部分である。 As described above, the
Here, in the
In the present invention, the thickness of the
本発明の圧電素子１０は、このような構成を有することにより、圧電素子１０を振動板に貼着する際など、圧電素子１０が押圧された際に、圧電フィルム１２の折り返し部において、圧電体層２６および電極層が破損することを防止できる。その結果、本発明の圧電素子１０は、例えば、エキサイターとして圧電スピーカーに用いられた際に、設定した動作を適正に行い、目的とする音圧での音声出力を適正に行うことができる。
Since 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.
上述のように、圧電フィルム１２を折り返して積層した圧電素子（積層圧電素子）は、一例として、振動板を振動させて音声を出力させるエキサイターとして用いられる。圧電素子をエキサイターとして用いて圧電スピーカーを作製する場合には、後述する図１２に概念的に示すように、圧電素子１０を振動板６２に貼着する必要がある。
圧電素子と振動板との貼着は、例えば、粘着剤等の貼着剤を介して、圧電素子を振動板に押圧することで行う。また、この押圧は、必要に応じて、貼着材すなわち、圧電素子および／または振動板を加熱しつつ行う。 As described above, a piezoelectric element (laminated piezoelectric element) in which thepiezoelectric film 12 is folded and laminated is used as, for example, an exciter that vibrates a diaphragm to output sound. When 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.
圧電素子と振動板との貼着は、例えば、粘着剤等の貼着剤を介して、圧電素子を振動板に押圧することで行う。また、この押圧は、必要に応じて、貼着材すなわち、圧電素子および／または振動板を加熱しつつ行う。 As described above, a piezoelectric element (laminated piezoelectric element) in which the
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.
ここで、圧電フィルムを折り返して積層した圧電素子では、この押圧の際に圧電フィルムに面圧がかかる。この面圧が折り返し部にかかると、圧電フィルムに負担がかかり、場合によっては、電極層および／または圧電体層が破断してしまうという問題がある。
Here, in a piezoelectric element in which the piezoelectric film is folded and laminated, surface pressure is applied to the piezoelectric film during this pressing. When this surface pressure is applied to the folded portion, the piezoelectric film is burdened, and in some cases, there is a problem that the electrode layer and/or the piezoelectric layer may be broken.
また、図示例のように、圧電体層２６に高分子複合圧電体を用いた圧電フィルム１２は、良好な可撓性を有する。そのため、この圧電フィルム１２を積層した圧電素子も、良好な可撓性を有する。従って、この場合には、巻取りが可能な振動板を用い、この振動板にエキサイターとして圧電素子を貼着ることにより、巻取りが可能な圧電スピーカーを実現できる。
しかしながら、この圧電スピーカーでは、振動板の巻取りの際に同様に圧電フィルムに面圧が掛かり、この面圧が折り返し部にかかると、場合によっては、電極層および／または圧電体層が破断してしまう。 Also, as shown in the drawing, thepiezoelectric 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
しかしながら、この圧電スピーカーでは、振動板の巻取りの際に同様に圧電フィルムに面圧が掛かり、この面圧が折り返し部にかかると、場合によっては、電極層および／または圧電体層が破断してしまう。 Also, as shown in the drawing, the
However, in this piezoelectric speaker, when the diaphragm is wound, the piezoelectric film is similarly subjected to surface pressure. end up
これに対して、本発明の圧電素子１０は、圧電フィルム１２を折り返すことで積層した（積層）圧電素子において、圧電素子１０の最厚部Ｍにおける貼着層２０の厚さをｔ、圧電素子１０の最厚部Ｍと、折り返し部の端部すなわち稜線との最短距離をＬとした際に、『Ｌ≧５０＊ｔ』を満たす。
すなわち、本発明の圧電素子１０では、最厚部Ｍと稜線との最短距離が、最厚部Ｍにおける貼着層２０の厚さｔの２０倍以上であり、十分に離れている。 On the other hand, thepiezoelectric 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 thepiezoelectric 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.
すなわち、本発明の圧電素子１０では、最厚部Ｍと稜線との最短距離が、最厚部Ｍにおける貼着層２０の厚さｔの２０倍以上であり、十分に離れている。 On the other hand, the
That is, in the
上述のように、圧電素子１０を振動板に貼着するための押圧において、圧電素子１０で最も高い圧力がかかるのは最厚部Ｍであり、最厚部Ｍの圧電フィルム１２に、最も高い面圧がかかる。
同様に、振動板を巻き取った際にも、圧電素子１０で最も高い圧力がかかるのは最厚部Ｍであり、最厚部Ｍの圧電フィルム１２に、最も高い面圧がかかる。 As described above, in the pressure for attaching thepiezoelectric element 10 to the diaphragm, 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.
Similarly, when the diaphragm is wound, the thickest portion M of thepiezoelectric 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.
同様に、振動板を巻き取った際にも、圧電素子１０で最も高い圧力がかかるのは最厚部Ｍであり、最厚部Ｍの圧電フィルム１２に、最も高い面圧がかかる。 As described above, in the pressure for attaching the
Similarly, when the diaphragm is wound, the thickest portion M of the
ここで、本発明の圧電素子１０は、上述のように、最厚部Ｍと稜線との最短距離Ｌが、最厚部における貼着層２０の厚さｔの２０倍以上である。すなわち、本発明の圧電素子１０は、最厚部Ｍを折り曲げ部に対して折り返し方向の内側に設けて、圧電フィルム１２が最も高い面圧を受ける最厚部Ｍと、圧電体層２６等の破断が生じやすい圧電フィルム１２の折り返し部とを、十分に離している。
そのため、本発明の圧電素子１０では、圧電フィルム１２は最厚部Ｍが最も高い面圧を受けることになり、最厚部Ｍと十分に離れてる折り曲げ部の圧電フィルム１２に高い面圧がかかることを防止できる。その結果、本発明の圧電素子１０は、振動板への押圧時等に、折り曲げ部において圧電体層２６および／または電極層の破断が生じることを防止できる。また、最厚部Ｍは、略平面状であるので、高い面圧がかかっても、圧電体層２６および電極層が破断することはない。
従って、本発明の圧電素子１０は、振動板への貼着等で押圧された後でも、所定の動作を適正に行うことができる。その結果、例えば本発明の圧電素子１０をエキサイターとして用いる圧電スピーカーは、設定した音圧の音声出力を適正に行うことができる。 Here, in thepiezoelectric element 10 of the present invention, as described above, 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.
Therefore, in thepiezoelectric element 10 of the present invention, 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. As a result, 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. Moreover, since 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.
Therefore, thepiezoelectric 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. As a result, for example, a piezoelectric speaker using the piezoelectric element 10 of the present invention as an exciter can properly output sound at a set sound pressure.
そのため、本発明の圧電素子１０では、圧電フィルム１２は最厚部Ｍが最も高い面圧を受けることになり、最厚部Ｍと十分に離れてる折り曲げ部の圧電フィルム１２に高い面圧がかかることを防止できる。その結果、本発明の圧電素子１０は、振動板への押圧時等に、折り曲げ部において圧電体層２６および／または電極層の破断が生じることを防止できる。また、最厚部Ｍは、略平面状であるので、高い面圧がかかっても、圧電体層２６および電極層が破断することはない。
従って、本発明の圧電素子１０は、振動板への貼着等で押圧された後でも、所定の動作を適正に行うことができる。その結果、例えば本発明の圧電素子１０をエキサイターとして用いる圧電スピーカーは、設定した音圧の音声出力を適正に行うことができる。 Here, in the
Therefore, in the
Therefore, the
本発明の圧電素子１０において、圧電素子１０の最厚部Ｍと、稜線すなわち折り曲げ部の端部との最短距離Ｌとは、圧電素子１０の平面形状における最短距離である。すなわち、圧電素子１０の最厚部Ｍと、稜線との最短距離Ｌとは、圧電素子１０を平面視した状態での最短距離である。
後述するが、本発明において、圧電素子１０の最厚部Ｍとは、圧電フィルム１２の折り返し方向すなわち図１における横方向における、圧電素子１０が最も厚い位置である。ここで、１枚の圧電フィルムを２回以上、折り返すことで、３層以上の圧電フィルム１２を積層した圧電素子では、折り返し方向の両端に折り返し部が存在する。この場合には、圧電フィルム１２の折り返し方向において、最厚部Ｍとの距離が近い方の折り返し部が、最短距離Ｌの対象となる。 In thepiezoelectric element 10 of the present invention, 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.
As will be described later, in the present invention, the thickest portion M of thepiezoelectric 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. Here, by folding one piezoelectric film two or more times, 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. In this case, in the folding direction of the piezoelectric film 12, the folded portion closer to the thickest portion M becomes the target of the shortest distance L. FIG.
後述するが、本発明において、圧電素子１０の最厚部Ｍとは、圧電フィルム１２の折り返し方向すなわち図１における横方向における、圧電素子１０が最も厚い位置である。ここで、１枚の圧電フィルムを２回以上、折り返すことで、３層以上の圧電フィルム１２を積層した圧電素子では、折り返し方向の両端に折り返し部が存在する。この場合には、圧電フィルム１２の折り返し方向において、最厚部Ｍとの距離が近い方の折り返し部が、最短距離Ｌの対象となる。 In the
As will be described later, in the present invention, the thickest portion M of the
また、本発明の圧電素子１０は、基本的に、図１に示すように、圧電フィルム１２の稜線の位置が、折り返し方向すなわち平面形状で一致するように、圧電フィルム１２を折り返して積層する。しかしながら、圧電素子１０によっては、図８に概念的に示すように、各折り返し部において、稜線の位置が、折り返し方向に異なる場合も有り得る。
この際には、平面形状すなわち平面視した際における距離が遠い方の稜線と最厚部Ｍとの距離Ｌ２ではなく、平面形状における距離が近い方の稜線と最厚部Ｍとの距離Ｌ１を、圧電素子１０における、最厚部Ｍと稜線（折り返し端部）との最短距離Ｌとする。 In thepiezoelectric element 10 of the present invention, basically, as shown in FIG. 1, 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. However, depending on the piezoelectric element 10, as conceptually shown in FIG. 8, the positions of the ridge lines may differ in the folding direction at each folded portion.
In this case, 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 thepiezoelectric element 10 .
この際には、平面形状すなわち平面視した際における距離が遠い方の稜線と最厚部Ｍとの距離Ｌ２ではなく、平面形状における距離が近い方の稜線と最厚部Ｍとの距離Ｌ１を、圧電素子１０における、最厚部Ｍと稜線（折り返し端部）との最短距離Ｌとする。 In the
In this case, 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
また、図１では、最上層の貼着層２０で最厚部Ｍの厚さｔを示しているが、１枚の圧電フィルムを２回以上、折り返すことで、３層以上の圧電フィルム１２を積層した圧電素子では、貼着層２０が、複数層、存在する。例えば、図１に示すように、圧電フィルム１２を４回折り返して、５層を積層した場合には、貼着層２０は、４層、存在する。
この場合には、各貼着層２０の最厚部Ｍにおける厚さの平均値を、圧電素子１０の最厚部Ｍにおける貼着層２０の厚さｔとする。例えば、図１の場合には、４つの貼着層２０の、それぞれの最厚部Ｍにおける貼着層２０の厚さの平均値を、圧電素子１０の最厚部における貼着層２０の厚さｔとする。 In addition, although FIG. 1 shows the thickness t of the thickest portion M of theadhesive 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. In the laminated piezoelectric element, a plurality of adhesion layers 20 are present. For example, as shown in FIG. 1, when the piezoelectric film 12 is folded four times to laminate five layers, four adhesive layers 20 are present.
In this case, the thickness t of theadhesive 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.
この場合には、各貼着層２０の最厚部Ｍにおける厚さの平均値を、圧電素子１０の最厚部Ｍにおける貼着層２０の厚さｔとする。例えば、図１の場合には、４つの貼着層２０の、それぞれの最厚部Ｍにおける貼着層２０の厚さの平均値を、圧電素子１０の最厚部における貼着層２０の厚さｔとする。 In addition, although FIG. 1 shows the thickness t of the thickest portion M of the
In this case, the thickness t of the
なお、本発明の圧電素子１０における最厚部Ｍの決定方法、および、最厚部Ｍにおける貼着層２０の厚さｔの決定方法に関しては、後に詳述する。
また、以下の説明では、圧電フィルム１２の折り返し部の端部すなわち稜線と、圧電素子１０の最厚部Ｍとの最短距離Ｌを、単に『最短距離Ｌ』ともいう。さらに、最厚部Ｍにおける貼着層２０の厚さｔを、単に『貼着層の厚さｔ』ともいう。 A method for determining the thickest portion M of thepiezoelectric 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 thepiezoelectric 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".
また、以下の説明では、圧電フィルム１２の折り返し部の端部すなわち稜線と、圧電素子１０の最厚部Ｍとの最短距離Ｌを、単に『最短距離Ｌ』ともいう。さらに、最厚部Ｍにおける貼着層２０の厚さｔを、単に『貼着層の厚さｔ』ともいう。 A method for determining the thickest portion M of the
Further, in the following description, the shortest distance L between the edge of the folded portion of the
上述のように、本発明の圧電素子１０においては、最短距離Ｌと、貼着層の厚さｔとが、『Ｌ≧５０＊ｔ』を満たす。
最短距離Ｌが『５０＊ｔ』未満では、圧電フィルム１２の折り返し部と最厚部Ｍとが近すぎ、最も面圧が高い最厚部Ｍと同等の面圧が折り返し部の圧電フィルム１２にかかってしまう。その結果、折り返し部における圧電体層２６および電極層の破断を、十分に防止することができない。
なお、本発明の効果は、基本的に、圧電素子１０の最厚部Ｍが、圧電フィルム１２の稜線と離間するほど好適に得られる。最短距離Ｌは、『Ｌ≧６０＊ｔ』を満たすのが好ましい。
なお、最短距離Ｌの上限は、圧電素子１０の平面形状における、圧電フィルム１２の折り返し方向の長さの半分である。 As described above, in thepiezoelectric element 10 of the present invention, 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 thepiezoelectric 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.
In addition, basically, the effect of the present invention can be preferably obtained as the thickest portion M of thepiezoelectric 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 thepiezoelectric film 12 in the planar shape of the piezoelectric element 10 in the folding direction.
最短距離Ｌが『５０＊ｔ』未満では、圧電フィルム１２の折り返し部と最厚部Ｍとが近すぎ、最も面圧が高い最厚部Ｍと同等の面圧が折り返し部の圧電フィルム１２にかかってしまう。その結果、折り返し部における圧電体層２６および電極層の破断を、十分に防止することができない。
なお、本発明の効果は、基本的に、圧電素子１０の最厚部Ｍが、圧電フィルム１２の稜線と離間するほど好適に得られる。最短距離Ｌは、『Ｌ≧６０＊ｔ』を満たすのが好ましい。
なお、最短距離Ｌの上限は、圧電素子１０の平面形状における、圧電フィルム１２の折り返し方向の長さの半分である。 As described above, in the
If the shortest distance L is less than "50*t", the folded portion and the thickest portion M of the
In addition, basically, the effect of the present invention can be preferably obtained as the thickest portion M of the
The upper limit of the shortest distance L is half the length of the
以下、図９を参照して、圧電素子１０における、最短距離Ｌ、最厚部、および、貼着層の厚さｔの決定方法を説明する。
以下の説明では、便宜的に、圧電フィルム１２の折り返しによる折り返し部の端部における折り返し線の方向、すなわち、折り返し部における圧電フィルム１２の稜線の方向をｘ方向とする。また、稜線の方向であるｘ方向と直交する方向、すなわち、圧電素子１０における圧電フィルム１２の折り返し方向をｙ方向とする。 A method for determining the shortest distance L, the thickest portion, and the thickness t of the adhesive layer in thepiezoelectric element 10 will be described below with reference to FIG.
In the following description, for the sake of convenience, the direction of the folding line at the end of the folding portion of thepiezoelectric film 12, that is, the direction of the ridgeline of the piezoelectric film 12 at the folding portion is defined as the x direction. Also, 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.
以下の説明では、便宜的に、圧電フィルム１２の折り返しによる折り返し部の端部における折り返し線の方向、すなわち、折り返し部における圧電フィルム１２の稜線の方向をｘ方向とする。また、稜線の方向であるｘ方向と直交する方向、すなわち、圧電素子１０における圧電フィルム１２の折り返し方向をｙ方向とする。 A method for determining the shortest distance L, the thickest portion, and the thickness t of the adhesive layer in the
In the following description, for the sake of convenience, the direction of the folding line at the end of the folding portion of the
本発明において、圧電素子１０の最短距離Ｌ、最厚部、および、貼着層の厚さｔは、図９の下段の平面図に概念的に示すように、ｘ方向の中心線である中心測定線ｘ１、
圧電素子１０のｘ方向の長さ、すなわち、稜線の長さの５％だけ、ｘ方向の端部から内側の位置するｙ方向の測定線ｘ２および測定線ｘ３、ならびに、
中心測定線ｘ１と測定線ｘ２との中間に位置するｙ方向の測定線ｘ４、および、中心測定線ｘ１と測定線ｘ３との中間に位置するｙ方向の測定線ｘ５、の５本の線で測定を行って、決定する。 In the present invention, the shortest distance L, the thickest portion, and the thickness t of the adhesive layer of thepiezoelectric 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 thepiezoelectric 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.
圧電素子１０のｘ方向の長さ、すなわち、稜線の長さの５％だけ、ｘ方向の端部から内側の位置するｙ方向の測定線ｘ２および測定線ｘ３、ならびに、
中心測定線ｘ１と測定線ｘ２との中間に位置するｙ方向の測定線ｘ４、および、中心測定線ｘ１と測定線ｘ３との中間に位置するｙ方向の測定線ｘ５、の５本の線で測定を行って、決定する。 In the present invention, the shortest distance L, the thickest portion, and the thickness t of the adhesive layer of the
the x-direction length of the
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.
圧電素子１０の最短距離Ｌ、および、最厚部Ｍは、以下のように決定する。
まず、圧電素子１０の中心測定線ｘ１、および、測定線ｘ２～ｘ５の全ての測定線において、圧電素子１０の最も高い位置である最高点を検出する。
次いで、各測定線毎に、最高点と、平面形状における稜線との最短距離を測定する。なお、各折り返し部で稜線の位置がｙ方向に異なる場合には、この最短距離は、上述した図８と同様に、最高点に最も近い稜線との最短距離とする。
次いで、測定した各測定線の最高点と稜線との最短距離の平均値を算出する。この平均値を、圧電素子１０における、最厚部Ｍと、稜線すなわち折り返し部の端部との最短距離Ｌとする。また、対象となった稜線からｙ方向に最短距離Ｌの位置における、ｘ方向の全域を、圧電素子１０における最厚部Ｍとする。
すなわち、本発明の圧電素子１０において、最厚部Ｍとは、ｙ方向すなわち圧電フィルム１２の折り返し方向において、圧電素子１０が最も厚いｘ方向の位置すなわち稜線方向の位置である。 The shortest distance L and the thickest portion M of thepiezoelectric element 10 are determined as follows.
First, the highest point, which is the highest position of thepiezoelectric 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 thepiezoelectric element 10 . In addition, 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 thepiezoelectric 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 .
まず、圧電素子１０の中心測定線ｘ１、および、測定線ｘ２～ｘ５の全ての測定線において、圧電素子１０の最も高い位置である最高点を検出する。
次いで、各測定線毎に、最高点と、平面形状における稜線との最短距離を測定する。なお、各折り返し部で稜線の位置がｙ方向に異なる場合には、この最短距離は、上述した図８と同様に、最高点に最も近い稜線との最短距離とする。
次いで、測定した各測定線の最高点と稜線との最短距離の平均値を算出する。この平均値を、圧電素子１０における、最厚部Ｍと、稜線すなわち折り返し部の端部との最短距離Ｌとする。また、対象となった稜線からｙ方向に最短距離Ｌの位置における、ｘ方向の全域を、圧電素子１０における最厚部Ｍとする。
すなわち、本発明の圧電素子１０において、最厚部Ｍとは、ｙ方向すなわち圧電フィルム１２の折り返し方向において、圧電素子１０が最も厚いｘ方向の位置すなわち稜線方向の位置である。 The shortest distance L and the thickest portion M of the
First, the highest point, which is the highest position of the
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
That is, in the
圧電素子１０の最高点の位置は、例えば輪郭形状測定器を用いて、圧電素子１０の表面形状を測定することで検出すればよい。輪郭形状測定器としては、例えば、ミツトヨ社製のＣＶ－３０００が例示される。
また、圧電素子１０の最厚部Ｍの厚さ（後述する厚さＴ１）は、φ２ｍｍのフラットタイプの測定子を用いて、デジマチックインジケータによって測定する。最厚部Ｍの厚さも、圧電素子１０の中心測定線ｘ１、および、測定線ｘ２～ｘ５の全ての線で測定を行い、その平均値を、圧電素子１０における最厚部Ｍの厚さとする。デジマチックインジケータとしては、例えばミツトヨ社製のＩＤ－Ｓ１１２Ｘが例示される。
この測定に関しては、後述する圧電フィルム１２の折り返し部における圧電素子１０の厚さ（後述する厚さＴ２）も同様である。 The position of the highest point of thepiezoelectric element 10 may be detected by measuring the surface shape of the piezoelectric element 10 using, for example, a contour shape measuring instrument. As 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 thepiezoelectric 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. . An example of the Digimatic indicator is ID-S112X manufactured by Mitutoyo Corporation.
Regarding this measurement, the thickness of the piezoelectric element 10 (thickness T2, which will be described later) at the folded portion of thepiezoelectric film 12, which will be described later, is also the same.
また、圧電素子１０の最厚部Ｍの厚さ（後述する厚さＴ１）は、φ２ｍｍのフラットタイプの測定子を用いて、デジマチックインジケータによって測定する。最厚部Ｍの厚さも、圧電素子１０の中心測定線ｘ１、および、測定線ｘ２～ｘ５の全ての線で測定を行い、その平均値を、圧電素子１０における最厚部Ｍの厚さとする。デジマチックインジケータとしては、例えばミツトヨ社製のＩＤ－Ｓ１１２Ｘが例示される。
この測定に関しては、後述する圧電フィルム１２の折り返し部における圧電素子１０の厚さ（後述する厚さＴ２）も同様である。 The position of the highest point of the
The thickness of the thickest portion M (thickness T1, which will be described later) of the
Regarding this measurement, the thickness of the piezoelectric element 10 (thickness T2, which will be described later) at the folded portion of the
一方、最厚部Ｍにおける貼着層の厚さｔは、以下のように決定する。
まず、圧電素子１０の中心測定線ｘ１、および、測定線ｘ２～ｘ５の全てにおいて、決定した最厚部Ｍにおける貼着層２０の厚さを測定する。
なお、各測定線における最厚部Ｍの貼着層２０の厚さは、各測定線での断面において、最厚部ＭをＳＥＭ（走査型電子顕微鏡(Scanning Electron Microscope)）で観察し、このＳＥＭ画像を用いて、公知の方法で測定すればよい。
厚さの測定は、全ての貼着層２０の最厚部Ｍで行う。図１に示す圧電素子１０であれば、４層の貼着層２０を有するので、１断面につき４つの貼着層２０で最厚部Ｍにおける貼着層２０の厚さを測定する。
次いで、測定した全ての貼着層２０の最厚部Ｍにおける厚さの平均を算出して、その平均値を、圧電素子１０における、最厚部Ｍの貼着層２０の厚さｔとする。図１に示す圧電素子１０であれば、４層の貼着層２０を有する。従って、中心測定線ｘ１および測定線ｘ２～ｘ５の全てにおける測定と合わせて、『４層×５断面＝２０か所』における、最厚部Ｍにおける貼着層２０の厚さの平均値が、圧電素子１０の貼着層２０の厚さｔとなる。 On the other hand, the thickness t of the adhesive layer at the thickest portion M is determined as follows.
First, the thickness of theadhesive 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 theadhesive 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 thepiezoelectric element 10 shown in FIG. 1 has four adhesive layers 20, the thickness of the adhesive layer 20 at the thickest portion M is measured for four adhesive layers 20 per cross section.
Next, the average thickness of the thickest portion M of all theadhesive layers 20 measured is calculated, and the average value is taken as the thickness t of the adhesive layer 20 of the thickest portion M in the piezoelectric element 10. . The piezoelectric element 10 shown in FIG. 1 has four adhesion layers 20 . Therefore, the average value of the thickness of the adhesive layer 20 at the thickest portion M in "4 layers x 5 cross sections = 20 locations" is It is the thickness t of the adhesive layer 20 of the piezoelectric element 10 .
まず、圧電素子１０の中心測定線ｘ１、および、測定線ｘ２～ｘ５の全てにおいて、決定した最厚部Ｍにおける貼着層２０の厚さを測定する。
なお、各測定線における最厚部Ｍの貼着層２０の厚さは、各測定線での断面において、最厚部ＭをＳＥＭ（走査型電子顕微鏡(Scanning Electron Microscope)）で観察し、このＳＥＭ画像を用いて、公知の方法で測定すればよい。
厚さの測定は、全ての貼着層２０の最厚部Ｍで行う。図１に示す圧電素子１０であれば、４層の貼着層２０を有するので、１断面につき４つの貼着層２０で最厚部Ｍにおける貼着層２０の厚さを測定する。
次いで、測定した全ての貼着層２０の最厚部Ｍにおける厚さの平均を算出して、その平均値を、圧電素子１０における、最厚部Ｍの貼着層２０の厚さｔとする。図１に示す圧電素子１０であれば、４層の貼着層２０を有する。従って、中心測定線ｘ１および測定線ｘ２～ｘ５の全てにおける測定と合わせて、『４層×５断面＝２０か所』における、最厚部Ｍにおける貼着層２０の厚さの平均値が、圧電素子１０の貼着層２０の厚さｔとなる。 On the other hand, the thickness t of the adhesive layer at the thickest portion M is determined as follows.
First, the thickness of the
The thickness of the
Thickness measurement is performed at the thickest portion M of all the adhesive layers 20 . Since the
Next, the average thickness of the thickest portion M of all the
本発明の圧電素子１０において、最厚部Ｍの厚さには、制限はない。
ここで、本発明の圧電素子１０においては、最厚部Ｍの厚さをＴ１、圧電フィルム１２の折り返し部における圧電素子１０の厚さをＴ２とした際に、厚さＴ１が、厚さＴ２の１１５％以上であるのが好ましい。以下の説明では、圧電フィルム１２の折り返し部における圧電素子１０の厚さを、便宜的に『折り返し部の厚さ』ともいう。
言い換えれば、本発明の圧電素子１０においては、最厚部の厚さＴ１が、折り返し部の厚さＴ２の１．１５倍以上であるのが好ましい。
このような構成を有することにより、より好適に振動板に押圧した際および振動板と共に巻き取られた際などにおける、折り返し部での圧電体層２６および／または電極層の破断を防止できる、振動板に押圧された後および振動板と共に巻き取られた後におけるＥＳＲ（Equivalent Series Resistance（等価直列抵抗））の上昇を抑制し、より安定的で効率の良い駆動を行うことができる等の点で好ましい。
最厚部の厚さＴ１は、折り返し部の厚さＴ２の１１６％以上であるのがより好ましく、１１７％以上であるのがさらに好ましい。 In thepiezoelectric element 10 of the present invention, the thickness of the thickest portion M is not limited.
Here, in thepiezoelectric element 10 of the present invention, when the thickness of the thickest portion M is T1 and the thickness of the piezoelectric element 10 at the folded portion of the piezoelectric film 12 is T2, the thickness T1 is equal to the thickness T2. of 115% or more. In the following description, 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.
In other words, in thepiezoelectric element 10 of the present invention, the thickness T1 of the thickest portion is preferably 1.15 times or more the thickness T2 of the folded portion.
By having such a configuration, thepiezoelectric 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. In terms of suppressing the increase in ESR (Equivalent Series Resistance) after being pressed by the plate and after being wound together with the diaphragm, enabling more stable and efficient driving. preferable.
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.
ここで、本発明の圧電素子１０においては、最厚部Ｍの厚さをＴ１、圧電フィルム１２の折り返し部における圧電素子１０の厚さをＴ２とした際に、厚さＴ１が、厚さＴ２の１１５％以上であるのが好ましい。以下の説明では、圧電フィルム１２の折り返し部における圧電素子１０の厚さを、便宜的に『折り返し部の厚さ』ともいう。
言い換えれば、本発明の圧電素子１０においては、最厚部の厚さＴ１が、折り返し部の厚さＴ２の１．１５倍以上であるのが好ましい。
このような構成を有することにより、より好適に振動板に押圧した際および振動板と共に巻き取られた際などにおける、折り返し部での圧電体層２６および／または電極層の破断を防止できる、振動板に押圧された後および振動板と共に巻き取られた後におけるＥＳＲ（Equivalent Series Resistance（等価直列抵抗））の上昇を抑制し、より安定的で効率の良い駆動を行うことができる等の点で好ましい。
最厚部の厚さＴ１は、折り返し部の厚さＴ２の１１６％以上であるのがより好ましく、１１７％以上であるのがさらに好ましい。 In the
Here, in the
In other words, in the
By having such a configuration, the
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.
また、最厚部の厚さＴ１は、折り返し部の厚さＴ２の１３０％以下が好ましい。
最厚部の厚さＴ１が、折り返し部の厚さＴ２に対して厚すぎると、振動板等への貼着が困難になる、圧電素子１０の面方向への伸縮が不安定になる、巻取り可能な振動板を用いた場合に、巻取りを行った際に振動板に凹凸が生じる（写りが発生する）等の不都合が生じる可能性が有る。これに対して、最厚部の厚さＴ１を上述の範囲内とすることで、これらの不都合が生じることを、好適に回避できる。 Moreover, 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 thepiezoelectric 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.
最厚部の厚さＴ１が、折り返し部の厚さＴ２に対して厚すぎると、振動板等への貼着が困難になる、圧電素子１０の面方向への伸縮が不安定になる、巻取り可能な振動板を用いた場合に、巻取りを行った際に振動板に凹凸が生じる（写りが発生する）等の不都合が生じる可能性が有る。これに対して、最厚部の厚さＴ１を上述の範囲内とすることで、これらの不都合が生じることを、好適に回避できる。 Moreover, 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
なお、折り返し部の厚さは、圧電素子１０における最も上（積層方向の端部）の折り返しの屈曲部端部から、折り返し方向に内側の１ｍｍまでの部分を含むように、φ２ｍｍのフラットタイプの測定子を用いて、デジマチックインジケータによって圧電素子１０の厚さを測定し、最も厚い厚さを、圧電素子１０における折り返し部の厚さＴ２とする。
In addition, the thickness of the folded portion is a flat type of φ2 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 .
なお、本発明において、最厚部の厚さＴ１、および、折り返し部の厚さＴ２は、共に、図９に示す圧電素子１０の中心測定線ｘ１、および、測定線ｘ２～ｘ５において、最厚部および折り返し部の厚さを測定し、その平均値を、圧電素子１０における最厚部の厚さＴ１、および、折り返し部の厚さＴ２とするのは、上述のとおりである。
In the present invention, 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. As described above, 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 .
以下、図１０の概念図を参照して、圧電素子１０の製造方法の一例を説明する。
上述のように、圧電素子１０は、圧電フィルム１２を折り返して積層し、かつ、積層によって隣接する圧電フィルム１２を、貼着層２０によって貼着したものである。
図１０の１段目および２段目に示すように、圧電フィルム１２の一方の端部近傍に貼着層２０を設け、次いで、３段目に示すように圧電フィルム１２を折り返して、積層する。１段目、２段目…とは、図中、上から段数を示す。
折り返して積層した圧電フィルム１２を、４段目に示すように、稜線方向の全域を押圧可能なローラ５０を折り返し方向に移動することにより、押圧して、積層した２層の圧電フィルム１２を貼着する。ローラ５０は、ローラ対を用いてもよい。また、必要に応じて、ローラ５０として加熱ローラを用い、加熱しつつ、圧電フィルム１２の貼着を行ってもよい。
さらに、５段目に示すように、積層した圧電フィルム１２の上に貼着層２０を設け、６段目に示すように、再度、圧電フィルム１２を折り返して、積層する。次いで、７段目に示すように、稜線方向の全域を押圧可能なローラ５０を折り返し方向に移動することにより、積層した圧電フィルム１２を貼着する。
この操作を、圧電フィルム１２の積層数に応じて、繰り返すことで、所望の層数、圧電フィルム１２を積層した圧電素子が製造できる。 An example of a method for manufacturing thepiezoelectric element 10 will be described below with reference to the conceptual diagram of FIG.
As described above, thepiezoelectric 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 .
As shown in the first and second rows of FIG. 10, anadhesive 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.
As shown in the fourth row, the folded and laminatedpiezoelectric 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. to wear A pair of rollers may be used for the rollers 50 . Further, if necessary, a heating roller may be used as the roller 50 to adhere the piezoelectric film 12 while heating.
Furthermore, as shown in the fifth row, theadhesive 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. Next, as shown in the seventh row, the laminated piezoelectric film 12 is adhered by moving the roller 50 capable of pressing the entire ridgeline direction in the folding direction.
By repeating this operation according to the number of layers of thepiezoelectric film 12, a piezoelectric element having a desired number of layers of the piezoelectric film 12 can be manufactured.
上述のように、圧電素子１０は、圧電フィルム１２を折り返して積層し、かつ、積層によって隣接する圧電フィルム１２を、貼着層２０によって貼着したものである。
図１０の１段目および２段目に示すように、圧電フィルム１２の一方の端部近傍に貼着層２０を設け、次いで、３段目に示すように圧電フィルム１２を折り返して、積層する。１段目、２段目…とは、図中、上から段数を示す。
折り返して積層した圧電フィルム１２を、４段目に示すように、稜線方向の全域を押圧可能なローラ５０を折り返し方向に移動することにより、押圧して、積層した２層の圧電フィルム１２を貼着する。ローラ５０は、ローラ対を用いてもよい。また、必要に応じて、ローラ５０として加熱ローラを用い、加熱しつつ、圧電フィルム１２の貼着を行ってもよい。
さらに、５段目に示すように、積層した圧電フィルム１２の上に貼着層２０を設け、６段目に示すように、再度、圧電フィルム１２を折り返して、積層する。次いで、７段目に示すように、稜線方向の全域を押圧可能なローラ５０を折り返し方向に移動することにより、積層した圧電フィルム１２を貼着する。
この操作を、圧電フィルム１２の積層数に応じて、繰り返すことで、所望の層数、圧電フィルム１２を積層した圧電素子が製造できる。 An example of a method for manufacturing the
As described above, the
As shown in the first and second rows of FIG. 10, an
As shown in the fourth row, the folded and laminated
Furthermore, as shown in the fifth row, the
By repeating this operation according to the number of layers of the
図１等に示されるように、本発明の圧電素子１０においては、圧電フィルム１２の厚さは、基本的に、全面的に均一（略均一）である。従って、圧電素子の厚さ、および、最厚部Ｍの位置および厚さは、貼着層２０の厚さで制御する。
図１０に示すような圧電素子の製造方法において、積層した圧電フィルム１２を貼着するためのローラ５０の押圧力を、ローラ５０の移動方向において部分的に調節する。すなわち、ローラ５０の押圧力を弱くすることで、その位置の貼着層２０を厚くし、その結果、圧電素子を厚くできる。
これにより、製造する圧電素子１０において、圧電フィルム１２の折り返し方向（図９におけるｙ方向）の任意の位置に、最厚部Ｍを設けることができる。
なお、圧電素子１０の製造において、ローラ５０の押圧力の変更は、全ての貼着層２０に対して行ってもよく、あるいは、ローラ５０の押圧力の変更を行わない貼着層２０を、１層または複数層、設定してもよい。 As shown in FIG. 1 and the like, in thepiezoelectric element 10 of the present invention, 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 .
In the method of manufacturing the piezoelectric element as shown in FIG. 10, the pressing force of theroller 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.
Thereby, in thepiezoelectric element 10 to be manufactured, 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 .
In the manufacture of thepiezoelectric element 10, 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.
図１０に示すような圧電素子の製造方法において、積層した圧電フィルム１２を貼着するためのローラ５０の押圧力を、ローラ５０の移動方向において部分的に調節する。すなわち、ローラ５０の押圧力を弱くすることで、その位置の貼着層２０を厚くし、その結果、圧電素子を厚くできる。
これにより、製造する圧電素子１０において、圧電フィルム１２の折り返し方向（図９におけるｙ方向）の任意の位置に、最厚部Ｍを設けることができる。
なお、圧電素子１０の製造において、ローラ５０の押圧力の変更は、全ての貼着層２０に対して行ってもよく、あるいは、ローラ５０の押圧力の変更を行わない貼着層２０を、１層または複数層、設定してもよい。 As shown in FIG. 1 and the like, in the
In the method of manufacturing the piezoelectric element as shown in FIG. 10, the pressing force of the
Thereby, in the
In the manufacture of the
本発明の圧電素子１０は、第１電極層２８および第２電極層３０に駆動電圧を印加することで、圧電体層２６を伸縮する。そのためには、第１電極層２８および第２電極層３０と外部電源などの外部の装置とを電気的に接続する必要がある。
第１電極層２８および第２電極層３０と、外部の装置とを接続する方法は、公知の各種の方法が利用可能である。 Thepiezoelectric 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 . 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.
Various known methods can be used to connect thefirst electrode layer 28 and the second electrode layer 30 to an external device.
第１電極層２８および第２電極層３０と、外部の装置とを接続する方法は、公知の各種の方法が利用可能である。 The
Various known methods can be used to connect the
一例として、図１１に概念的に示すように、圧電フィルム１２を、一方の端部で延長して、圧電フィルム１２が積層している領域から突出する突出部１２ａを設ける。その上で、この突出部１２ａに、外部の装置と電気的に接続するための引出配線を設ける方法が例示される。
なお、本発明において、突出部とは、具体的には、平面形状において、すなわち積層方向から見た際に、他の圧電フィルム１２とは重複しない、単層となっている領域を示す。また、図１１では、圧電素子１０の最厚部は省略している。 As an example, as conceptually shown in FIG. 11, thepiezoelectric film 12 is extended at one end to provide a protruding portion 12a protruding from the area where the piezoelectric film 12 is laminated. In addition, a method of providing a lead wiring for electrical connection with an external device to the projecting portion 12a is exemplified.
In the present invention, the protruding portion specifically indicates a single-layer region that does not overlap with otherpiezoelectric films 12 when viewed in a planar shape, that is, in the stacking direction. Also, in FIG. 11, the thickest part of the piezoelectric element 10 is omitted.
なお、本発明において、突出部とは、具体的には、平面形状において、すなわち積層方向から見た際に、他の圧電フィルム１２とは重複しない、単層となっている領域を示す。また、図１１では、圧電素子１０の最厚部は省略している。 As an example, as conceptually shown in FIG. 11, the
In the present invention, the protruding portion specifically indicates a single-layer region that does not overlap with other
図１１に示すように、圧電素子１０の突出部１２ａには、電源装置等の外部装置と電気的に接続するための第１引出配線７２および第２引出配線７４が接続されている。
第１引出配線７２は、第１電極層２８から電気的に引き出される配線であり、第２引出配線７４は、第２電極層３０から電気的に引き出される配線である。以下の説明では、第１引出配線７２と第２引出配線７４とを区別する必要が無い場合には、単に引出配線とも言う。 As shown in FIG. 11, the projectingportion 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.
Thefirst lead wire 72 is a wire electrically led out from the first electrode layer 28 , and the second lead wire 74 is a wire electrically led out from the second electrode layer 30 . In the following description, 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.
第１引出配線７２は、第１電極層２８から電気的に引き出される配線であり、第２引出配線７４は、第２電極層３０から電気的に引き出される配線である。以下の説明では、第１引出配線７２と第２引出配線７４とを区別する必要が無い場合には、単に引出配線とも言う。 As shown in FIG. 11, the projecting
The
本発明の圧電素子１０において、電極層と引出配線との接続方法、すなわち引出方法には、制限はなく、各種の方法が利用可能である。
一例として、保護層に貫通孔を形成し、貫通孔を埋めるように銀ペースト等の金属ペーストで形成した電極接続部材を設け、この電極接続部材に引出配線を設ける方法が例示される。
別の方法として、電極層と圧電体層との間、または、電極層と保護層との間に、棒状またはシート状の引出し用の電極を設け、この引出し用の電極に引出配線を接続する方法が例示される。あるいは、引出配線を、直接、電極層と圧電体層との間、または、電極層と保護層との間に挿入して、引出配線を電極層に接続してもよい。
別の方法として、保護層および電極層の一部を面方向に圧電体層から突出させ、突出した電極層に、引出配線を接続する方法が例示される。なお、引出配線と電極層との接続は、銀ペースト等の金属ペーストを用いる方法、半田を用いる方法、導電性の接着剤を用いる方法等の公知の方法で行えばよい。
好適な電極の引き出し方法として、特開２０１４－２０９７２４号公報に記載される方法、および、特開２０１６－０１５３５４号公報に記載される方法等が例示される。 In thepiezoelectric element 10 of the present invention, the method of connecting the electrode layer and the lead wire, ie, the lead method, is not limited, and various methods can be used.
As an example, 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.
Alternatively, 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. Alternatively, 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.
As another method, 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.
一例として、保護層に貫通孔を形成し、貫通孔を埋めるように銀ペースト等の金属ペーストで形成した電極接続部材を設け、この電極接続部材に引出配線を設ける方法が例示される。
別の方法として、電極層と圧電体層との間、または、電極層と保護層との間に、棒状またはシート状の引出し用の電極を設け、この引出し用の電極に引出配線を接続する方法が例示される。あるいは、引出配線を、直接、電極層と圧電体層との間、または、電極層と保護層との間に挿入して、引出配線を電極層に接続してもよい。
別の方法として、保護層および電極層の一部を面方向に圧電体層から突出させ、突出した電極層に、引出配線を接続する方法が例示される。なお、引出配線と電極層との接続は、銀ペースト等の金属ペーストを用いる方法、半田を用いる方法、導電性の接着剤を用いる方法等の公知の方法で行えばよい。
好適な電極の引き出し方法として、特開２０１４－２０９７２４号公報に記載される方法、および、特開２０１６－０１５３５４号公報に記載される方法等が例示される。 In the
As an example, 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.
Alternatively, 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. Alternatively, 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.
As another method, 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.
また、圧電素子１０において、圧電フィルム１２の端部を延長するのではなく、国際公開第２０２０／０９５８１２号の図１８に示されるように、圧電フィルム１２の稜線の方向すなわち折り返し方向と直交する方向に、圧電フィルムから突出する出島のような突出部を設け、此処に外部の装置を接続するための引出し配線を設けてもよい。
さらに、本発明の圧電素子では、必要に応じて、これらの突出部を、複数、併用してもよい。 Moreover, in thepiezoelectric element 10, instead of extending the end of the piezoelectric film 12, as shown in FIG. In addition, 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.
Furthermore, in the piezoelectric element of the present invention, a plurality of these protrusions may be used together as required.
さらに、本発明の圧電素子では、必要に応じて、これらの突出部を、複数、併用してもよい。 Moreover, in the
Furthermore, in the piezoelectric element of the present invention, a plurality of these protrusions may be used together as required.
本発明の圧電素子１０は、後述するように、各種の用途に利用可能である。中でも、本発明の圧電素子１０は、振動板を振動させることで音声を出力させるエキサイターとして、好適に利用される。
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.
図１２に、本発明の圧電スピーカーの一例を概念的に示す。
本発明の圧電スピーカーは、本発明の圧電素子１０を振動板に貼着して、振動板を振動させて音声を出力させる、エキサイターとして用いるものである。
図１２に示すように、圧電スピーカー６０は、貼着層６８によって、振動板６２に圧電素子１０を貼着したものである。なお、本発明の圧電スピーカーにおいて、１枚の振動板６２に貼着する圧電素子の数は、１つに制限はされず、複数の圧電素子１０を１枚の振動板６２に貼着してもよい。また、例えば、２つの圧電素子１０を１枚の振動板６２に設け、各圧電素子１０に異なる駆動電圧を印加することで、１枚の振動板６２で例えばステレオ音声の出力を行うようにしてもよい。 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 thepiezoelectric element 10 of the present invention to a diaphragm and vibrating the diaphragm to output sound.
As shown in FIG. 12, thepiezoelectric speaker 60 has a piezoelectric element 10 attached to a diaphragm 62 with an adhesive layer 68 . In the piezoelectric speaker of the present invention, 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.
本発明の圧電スピーカーは、本発明の圧電素子１０を振動板に貼着して、振動板を振動させて音声を出力させる、エキサイターとして用いるものである。
図１２に示すように、圧電スピーカー６０は、貼着層６８によって、振動板６２に圧電素子１０を貼着したものである。なお、本発明の圧電スピーカーにおいて、１枚の振動板６２に貼着する圧電素子の数は、１つに制限はされず、複数の圧電素子１０を１枚の振動板６２に貼着してもよい。また、例えば、２つの圧電素子１０を１枚の振動板６２に設け、各圧電素子１０に異なる駆動電圧を印加することで、１枚の振動板６２で例えばステレオ音声の出力を行うようにしてもよい。 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
As shown in FIG. 12, the
本発明の圧電スピーカー６０において、振動板６２には、制限はなく、エキサイターによる振動によって音声を出力する振動板として作用するものであれば、各種のシート状物が利用可能である。
In the piezoelectric speaker 60 of the present invention, 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.
本発明の圧電スピーカー６０において、振動板６２としては、一例として、ポリエチレンテレフタレート（ＰＥＴ）、ポリプロピレン（ＰＰ）、ポリスチレン（ＰＳ）、ポリカーボネート（ＰＣ）、ポリフェニレンサルファイト（ＰＰＳ）、ポリメチルメタクリレート（ＰＭＭＡ）、ポリエーテルイミド（ＰＥＩ）、ポリイミド（ＰＩ）、ポリエチレンナフタレート（ＰＥＮ）、トリアセチルセルロース（ＴＡＣ）および環状オレフィン系樹脂などからなる樹脂フィルム、発泡ポリスチレン、発泡スチレンおよび発泡ポリエチレンなどからなる発泡プラスチックシート、ならびに、波状にした板紙の片面または両面に他の板紙をはりつけてなる各種の段ボール材等が例示される。
また、本発明の圧電スピーカー６０は、振動板６２として、有機エレクトロルミネセンス（ＯＬＥＤ（Organic Light Emitting Diode）ディスプレイ、液晶ディスプレイ、マイクロＬＥＤ（Light Emitting Diode）ディスプレイ、および、無機エレクトロルミネセンスディスプレイなどの各種の表示デバイス等も好適に利用可能である。
さらに、本発明の圧電スピーカー６０は、振動板６２として、スマートフォン、携帯電話、タブレット端末、ノートパソコンなどのパーソナルコンピュータ、および、スマートウォッチなどのウェアラブルデバイス等の電子デバイスも好適に利用可能である。
これ以外にも、本発明の圧電スピーカーは、振動板６２として、ステンレス、アルミニウム、銅およびニッケルなどの各種の金属、ならびに、各種の合金などからなる薄膜金属も好適に利用可能である。
振動板６２が表示デバイスおよび電子デバイス等である場合を含め、振動板６２は、可撓性を有するものであってもよい。上述のように、圧電フィルム１２は良好な可撓性を有する。そのため、圧電フィルム１２を積層した本発明の積層圧電素子１０も、良好な可撓性を有する。従って、可撓性を有する振動板６２を用いることにより、湾曲、折り曲げ、折り畳み、および、巻取り等が可能な圧電スピーカーを実現できる。 In thepiezoelectric speaker 60 of the present invention, 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. Examples include plastic sheets and various corrugated board materials obtained by attaching another paperboard to one or both sides of corrugated paperboard.
In addition, thepiezoelectric 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. Various display devices and the like can also be suitably used.
Furthermore, thepiezoelectric 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.
In addition to this, 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 thediaphragm 62 .
Thediaphragm 62 may be flexible, including the case where the diaphragm 62 is a display device, an electronic device, or the like. As mentioned above, 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.
また、本発明の圧電スピーカー６０は、振動板６２として、有機エレクトロルミネセンス（ＯＬＥＤ（Organic Light Emitting Diode）ディスプレイ、液晶ディスプレイ、マイクロＬＥＤ（Light Emitting Diode）ディスプレイ、および、無機エレクトロルミネセンスディスプレイなどの各種の表示デバイス等も好適に利用可能である。
さらに、本発明の圧電スピーカー６０は、振動板６２として、スマートフォン、携帯電話、タブレット端末、ノートパソコンなどのパーソナルコンピュータ、および、スマートウォッチなどのウェアラブルデバイス等の電子デバイスも好適に利用可能である。
これ以外にも、本発明の圧電スピーカーは、振動板６２として、ステンレス、アルミニウム、銅およびニッケルなどの各種の金属、ならびに、各種の合金などからなる薄膜金属も好適に利用可能である。
振動板６２が表示デバイスおよび電子デバイス等である場合を含め、振動板６２は、可撓性を有するものであってもよい。上述のように、圧電フィルム１２は良好な可撓性を有する。そのため、圧電フィルム１２を積層した本発明の積層圧電素子１０も、良好な可撓性を有する。従って、可撓性を有する振動板６２を用いることにより、湾曲、折り曲げ、折り畳み、および、巻取り等が可能な圧電スピーカーを実現できる。 In the
In addition, the
Furthermore, the
In addition to this, 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
The
本発明の圧電スピーカー６０において、振動板６２と圧電素子１０とを貼着する貼着層６８には、制限はなく、振動板６２と圧電素子１０（圧電フィルム１２）とを貼着可能であれば、各種の貼着剤が利用可能である。
本発明の圧電スピーカー６０において、振動板６２と圧電素子１０とを貼着する貼着層６８は、上述した隣接する圧電フィルム１２を貼着する貼着層２０と同様のものが、各種、利用可能である。また、好ましい貼着層６８も、同様である。 In thepiezoelectric speaker 60 of the present invention, 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). For example, various adhesives are available.
In thepiezoelectric speaker 60 of the present invention, 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.
本発明の圧電スピーカー６０において、振動板６２と圧電素子１０とを貼着する貼着層６８は、上述した隣接する圧電フィルム１２を貼着する貼着層２０と同様のものが、各種、利用可能である。また、好ましい貼着層６８も、同様である。 In the
In the
本発明の圧電スピーカー６０において、貼着層６８の厚さには制限はなく、貼着層６８の形成材料に応じて、十分な貼着力を発現できる厚さを、適宜、設定すればよい。
ここで、本発明の圧電スピーカー６０では、貼着層６８は、薄い方が、圧電フィルム１２の伸縮エネルギー（振動エネルギー）の伝達効果を高くして、エネルギー効率を高くできる。また、貼着層が厚く剛性が高いと圧電素子１０の伸縮を拘束する可能性もある。
この点を考慮すると、振動板６２と圧電素子１０とを貼着する貼着層６８の厚さは、貼着後の厚さで１０～１０００μｍが好ましく、３０～５００μｍがより好ましく、５０～３００μｍがさらに好ましい。 In thepiezoelectric speaker 60 of the present invention, 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 .
Here, in thepiezoelectric speaker 60 of the present invention, 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. Also, if the adhesive layer is thick and rigid, it may restrict expansion and contraction of the piezoelectric element 10 .
In consideration of this point, the thickness of theadhesive layer 68 that attaches the vibration plate 62 and the piezoelectric element 10 is preferably 10 to 1000 μm, more preferably 30 to 500 μm, more preferably 50 to 300 μm. is more preferred.
ここで、本発明の圧電スピーカー６０では、貼着層６８は、薄い方が、圧電フィルム１２の伸縮エネルギー（振動エネルギー）の伝達効果を高くして、エネルギー効率を高くできる。また、貼着層が厚く剛性が高いと圧電素子１０の伸縮を拘束する可能性もある。
この点を考慮すると、振動板６２と圧電素子１０とを貼着する貼着層６８の厚さは、貼着後の厚さで１０～１０００μｍが好ましく、３０～５００μｍがより好ましく、５０～３００μｍがさらに好ましい。 In the
Here, in the
In consideration of this point, the thickness of the
上述のように、本発明の圧電素子１０において、圧電フィルム１２は、圧電体層２６を第１電極層２８および第２電極層３０で挟持したものである。
好ましくは、圧電体層２６は、高分子マトリックス３８中に、圧電体粒子４０を分散したものである。 As described above, in thepiezoelectric element 10 of the present invention, the piezoelectric film 12 has the piezoelectric layer 26 sandwiched between the first electrode layer 28 and the second electrode layer 30 .
Preferably,piezoelectric layer 26 comprises piezoelectric particles 40 dispersed in polymer matrix 38 .
好ましくは、圧電体層２６は、高分子マトリックス３８中に、圧電体粒子４０を分散したものである。 As described above, in the
Preferably,
このような圧電体層２６を有する圧電フィルム１２の第２電極層３０および第１電極層２８に電圧を印加すると、印加した電圧に応じて圧電体粒子４０が分極方向に伸縮する。その結果、圧電フィルム１２（圧電体層２６）が厚さ方向に収縮する。同時に、ポアゾン比の関係で、圧電フィルム１２は、面方向にも伸縮する。
この伸縮は、０．０１～０．１％程度である。
上述したように、圧電体層２６の厚さは、好ましくは８～３００μｍ程度である。従って、厚さ方向の伸縮は、最大でも０．３μｍ程度と非常に小さい。
これに対して、圧電フィルム１２すなわち圧電体層２６は、面方向には、厚さよりも遥かに大きなサイズを有する。従って、例えば、圧電フィルム１２の長さが２０ｃｍであれば、電圧の印加によって、最大で０．２ｍｍ程度、圧電フィルム１２は伸縮する。 When a voltage is applied to thesecond electrode layer 30 and the first electrode layer 28 of the piezoelectric film 12 having such a piezoelectric layer 26, the piezoelectric particles 40 expand and contract in the polarization direction according to the applied voltage. As a result, the piezoelectric film 12 (piezoelectric layer 26) shrinks in the thickness direction. At the same time, due to the Poisson's ratio, the piezoelectric film 12 expands and contracts in the plane direction as well.
This expansion and contraction is about 0.01 to 0.1%.
As described above, the thickness of thepiezoelectric layer 26 is preferably about 8-300 μm. Therefore, the expansion and contraction in the thickness direction is as small as about 0.3 μm at maximum.
On the other hand, thepiezoelectric 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.
この伸縮は、０．０１～０．１％程度である。
上述したように、圧電体層２６の厚さは、好ましくは８～３００μｍ程度である。従って、厚さ方向の伸縮は、最大でも０．３μｍ程度と非常に小さい。
これに対して、圧電フィルム１２すなわち圧電体層２６は、面方向には、厚さよりも遥かに大きなサイズを有する。従って、例えば、圧電フィルム１２の長さが２０ｃｍであれば、電圧の印加によって、最大で０．２ｍｍ程度、圧電フィルム１２は伸縮する。 When a voltage is applied to the
This expansion and contraction is about 0.01 to 0.1%.
As described above, the thickness of the
On the other hand, the
上述したように、圧電素子１０は、折り返すことによって、圧電フィルム１２を、５層、積層したものである。また、圧電素子１０は、貼着層６８によって振動板６２に貼着される。
圧電フィルム１２の伸縮によって、圧電素子１０も同方向に伸縮する。この圧電素子１０の伸縮によって、振動板６２は撓み、その結果、厚さ方向に振動する。
この厚さ方向の振動によって、振動板６２は、音を発生する。すなわち、振動板６２は、圧電フィルム１２に印加した電圧（駆動電圧）の大きさに応じて振動して、圧電フィルム１２に印加した駆動電圧に応じた音を発生する。 As described above, thepiezoelectric 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 thepiezoelectric 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 thediaphragm 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 .
圧電フィルム１２の伸縮によって、圧電素子１０も同方向に伸縮する。この圧電素子１０の伸縮によって、振動板６２は撓み、その結果、厚さ方向に振動する。
この厚さ方向の振動によって、振動板６２は、音を発生する。すなわち、振動板６２は、圧電フィルム１２に印加した電圧（駆動電圧）の大きさに応じて振動して、圧電フィルム１２に印加した駆動電圧に応じた音を発生する。 As described above, the
As the
This vibration in the thickness direction causes the
ここで、ＰＶＤＦ等の高分子材料からなる一般的な圧電フィルムは、分極処理後に一軸方向に延伸処理することで、延伸方向に対して分子鎖が配向し、結果として延伸方向に大きな圧電特性が得られることが知られている。そのため、一般的な圧電フィルムは、圧電特性に面内異方性を有し、電圧を印加された場合の面方向の伸縮量に異方性がある。
これに対して、圧電素子１０において、図４に示す高分子マトリックス３８中に圧電体粒子４０を分散してなる高分子複合圧電体からなる圧電フィルム１２は、分極処理後に延伸処理をせずとも大きな圧電特性が得られるため、圧電特性に面内異方性がなく、面方向では全方向に等方的に伸縮する。すなわち、図示例の圧電素子１０において、圧電素子１０を構成する図４に示す圧電フィルム１２は、等方的に二次元的に伸縮する。このような等方的に二次元的に伸縮する圧電フィルム１２を積層した圧電素子１０によれば、一方向にしか大きく伸縮しないＰＶＤＦ等の一般的な圧電フィルムを積層した場合に比べ、大きな力で振動板６２を振動することができ、より大きく、かつ、美しい音を発生できる。 Here, in 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.
On the other hand, in thepiezoelectric element 10, the piezoelectric film 12 made of the polymer composite piezoelectric body in which the piezoelectric particles 40 are dispersed in the polymer matrix 38 shown in FIG. 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.
これに対して、圧電素子１０において、図４に示す高分子マトリックス３８中に圧電体粒子４０を分散してなる高分子複合圧電体からなる圧電フィルム１２は、分極処理後に延伸処理をせずとも大きな圧電特性が得られるため、圧電特性に面内異方性がなく、面方向では全方向に等方的に伸縮する。すなわち、図示例の圧電素子１０において、圧電素子１０を構成する図４に示す圧電フィルム１２は、等方的に二次元的に伸縮する。このような等方的に二次元的に伸縮する圧電フィルム１２を積層した圧電素子１０によれば、一方向にしか大きく伸縮しないＰＶＤＦ等の一般的な圧電フィルムを積層した場合に比べ、大きな力で振動板６２を振動することができ、より大きく、かつ、美しい音を発生できる。 Here, in 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.
On the other hand, in the
上述したように、図示例の圧電素子１０は、このような圧電フィルム１２を、５層、積層したものである。図示例の圧電素子１０は、さらに、隣接する圧電フィルム１２同士を、貼着層２０で貼着している。
そのため、１枚毎の圧電フィルム１２の剛性が低く、伸縮力は小さくても、圧電フィルム１２を積層することにより、剛性が高くなり、圧電素子１０としての伸縮力は大きくなる。その結果、圧電素子１０は、振動板６２がある程度の剛性を有するものであっても、大きな力で振動板６２を十分に撓ませて、厚さ方向に振動板６２を十分に振動させて、振動板６２に音を発生させることができる。
また、圧電体層２６が厚い方が、圧電フィルム１２の伸縮力は大きくなるが、その分、同じ量、伸縮させるのに必要な駆動電圧は大きくなる。ここで、上述したように、圧電素子１０において、好ましい圧電体層２６の厚さは、最大でも３００μｍ程度であるので、個々の圧電フィルム１２に印加する電圧が小さくても、十分に、圧電フィルム１２を伸縮させることが可能である。 As described above, the illustratedpiezoelectric element 10 is formed by laminating five such piezoelectric films 12 . In the illustrated piezoelectric element 10 , the adjoining piezoelectric films 12 are further attached to each other with an adhesive layer 20 .
Therefore, even if the rigidity of eachpiezoelectric 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 .
Also, the thicker thepiezoelectric layer 26, the greater the expansion/contraction force of the piezoelectric film 12, but the drive voltage required for the same amount of expansion/contraction increases accordingly. Here, as described above, in the piezoelectric element 10, the preferable thickness of the piezoelectric layer 26 is about 300 μm at most. 12 can be stretched.
そのため、１枚毎の圧電フィルム１２の剛性が低く、伸縮力は小さくても、圧電フィルム１２を積層することにより、剛性が高くなり、圧電素子１０としての伸縮力は大きくなる。その結果、圧電素子１０は、振動板６２がある程度の剛性を有するものであっても、大きな力で振動板６２を十分に撓ませて、厚さ方向に振動板６２を十分に振動させて、振動板６２に音を発生させることができる。
また、圧電体層２６が厚い方が、圧電フィルム１２の伸縮力は大きくなるが、その分、同じ量、伸縮させるのに必要な駆動電圧は大きくなる。ここで、上述したように、圧電素子１０において、好ましい圧電体層２６の厚さは、最大でも３００μｍ程度であるので、個々の圧電フィルム１２に印加する電圧が小さくても、十分に、圧電フィルム１２を伸縮させることが可能である。 As described above, the illustrated
Therefore, even if the rigidity of each
Also, the thicker the
このような本発明の圧電素子は、上述のような圧電スピーカー以外にも、例えば、各種のセンサー、音響デバイス、ハプティクス、超音波トランスデューサー、アクチュエータ、制振材（ダンパー）、および、振動発電装置等、各種の用途に好適に利用される。
具体的には、本発明の圧電素子を用いるセンサーとしては、音波センサー、超音波センサー、圧力センサー、触覚センサー、歪みセンサー、および、振動センサー等が例示される。本発明の圧電フィルムおよび積層圧電素子を用いるセンサーは、特に、ひび検知等のインフラ点検、および、異物混入検知など、製造現場における検査に有用である。
本発明の圧電素子を用いる音響デバイスとしては、上述のような圧電スピーカー（エキサイター）以外にも、マイクロフォン、ピックアップ、ならびに、公知の各種のスピーカーおよびエキサイター等が例示される。本発明の圧電素子を用いる音響デバイスの具体的な用途としては、車、電車、飛行機およびロボット等に使用されるノイズキャンセラー、人工声帯、害虫・害獣侵入防止用ブザー、ならびに、音声出力機能を有する家具、壁紙、写真、ヘルメット、ゴーグル、ヘッドレスト、サイネージおよびロボットなどが例示される。
本発明の圧電素子を用いるハプティクスの適用例としては、自動車、スマートフォン、スマートウォッチ、および、ゲーム機等が例示される。
本発明の圧電素子を用いる超音波トランスデューサーとしては、超音波探触子、および、ハイドロホン等が例示される。
本発明の圧電素子を用いるアクチュエータの用途としては、水滴付着防止、輸送、攪拌、分散、および、研磨等が例示される。
本発明の圧電素子を用いる制振材の適用例としては、容器、乗り物、建物、ならびに、スキーおよびラケット等のスポーツ用具などが例示される。
さらに、本発明の圧電素子を用いる振動発電装置の適用例としては、道路、床、マットレス、椅子、靴、タイヤ、車輪、および、パソコンキーボード等が例示される。 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.
Specifically, 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.
Further, 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.
具体的には、本発明の圧電素子を用いるセンサーとしては、音波センサー、超音波センサー、圧力センサー、触覚センサー、歪みセンサー、および、振動センサー等が例示される。本発明の圧電フィルムおよび積層圧電素子を用いるセンサーは、特に、ひび検知等のインフラ点検、および、異物混入検知など、製造現場における検査に有用である。
本発明の圧電素子を用いる音響デバイスとしては、上述のような圧電スピーカー（エキサイター）以外にも、マイクロフォン、ピックアップ、ならびに、公知の各種のスピーカーおよびエキサイター等が例示される。本発明の圧電素子を用いる音響デバイスの具体的な用途としては、車、電車、飛行機およびロボット等に使用されるノイズキャンセラー、人工声帯、害虫・害獣侵入防止用ブザー、ならびに、音声出力機能を有する家具、壁紙、写真、ヘルメット、ゴーグル、ヘッドレスト、サイネージおよびロボットなどが例示される。
本発明の圧電素子を用いるハプティクスの適用例としては、自動車、スマートフォン、スマートウォッチ、および、ゲーム機等が例示される。
本発明の圧電素子を用いる超音波トランスデューサーとしては、超音波探触子、および、ハイドロホン等が例示される。
本発明の圧電素子を用いるアクチュエータの用途としては、水滴付着防止、輸送、攪拌、分散、および、研磨等が例示される。
本発明の圧電素子を用いる制振材の適用例としては、容器、乗り物、建物、ならびに、スキーおよびラケット等のスポーツ用具などが例示される。
さらに、本発明の圧電素子を用いる振動発電装置の適用例としては、道路、床、マットレス、椅子、靴、タイヤ、車輪、および、パソコンキーボード等が例示される。 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.
Specifically, 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.
Further, 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.
以上、本発明の圧電素子および圧電スピーカーについて詳細に説明したが、本発明は上述の例に限定はされず、本発明の要旨を逸脱しない範囲において、各種の改良や変更を行ってもよいのは、もちろんである。
Although the piezoelectric element and piezoelectric speaker of the present invention have been described in detail above, the present invention is not limited to the above examples, and various improvements and modifications may be made without departing from the scope of the present invention. is of course.
以下、本発明の具体的な実施例を挙げ、本発明について、より詳細に説明する。
Hereinafter, the present invention will be described in more detail by giving specific examples of the present invention.
［圧電フィルムの作製］
図５～図７に示す方法で、図４に示すような圧電フィルムを作製した。
まず、下記の組成比で、シアノエチル化ＰＶＡ（ＣＲ－Ｖ、信越化学工業社製）をジメチルホルムアミド（ＤＭＦ）に溶解した。その後、この溶液に、圧電体粒子としてＰＺＴ粒子を下記の組成比で添加して、プロペラミキサー（回転数２０００ｒｐｍ）で攪拌して、圧電体層を形成するための塗料を調製した。
・ＰＺＴ粒子・・・・・・・・・・・３００質量部
・シアノエチル化ＰＶＡ・・・・・・・３０質量部
・ＤＭＦ・・・・・・・・・・・・・・７０質量部
なお、ＰＺＴ粒子は、主成分となるＰｂ酸化物、Ｚｒ酸化物およびＴｉ酸化物の粉末を、Ｐｂ＝１モルに対し、Ｚｒ＝０．５２モル、Ｔｉ＝０．４８モルとなるように、ボールミルで湿式混合してなる混合粉を、８００℃で５時間、焼成した後、解砕処理したものを用いた。 [Preparation of piezoelectric film]
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.
・PZT particles・・・・・・・・・・300 parts by mass ・Cyanoethylated PVA・・・・・・・・30 parts by mass ・DMF・・・・・・・・・・・・70 parts by mass The PZT particles are composed of powders of Pb oxide, Zr oxide and Ti oxide, which are the main components, so that Zr = 0.52 mol and Ti = 0.48 mol with respect to Pb = 1 mol. Mixed powder obtained by wet-mixing in a ball mill was fired at 800° C. for 5 hours and then pulverized.
図５～図７に示す方法で、図４に示すような圧電フィルムを作製した。
まず、下記の組成比で、シアノエチル化ＰＶＡ（ＣＲ－Ｖ、信越化学工業社製）をジメチルホルムアミド（ＤＭＦ）に溶解した。その後、この溶液に、圧電体粒子としてＰＺＴ粒子を下記の組成比で添加して、プロペラミキサー（回転数２０００ｒｐｍ）で攪拌して、圧電体層を形成するための塗料を調製した。
・ＰＺＴ粒子・・・・・・・・・・・３００質量部
・シアノエチル化ＰＶＡ・・・・・・・３０質量部
・ＤＭＦ・・・・・・・・・・・・・・７０質量部
なお、ＰＺＴ粒子は、主成分となるＰｂ酸化物、Ｚｒ酸化物およびＴｉ酸化物の粉末を、Ｐｂ＝１モルに対し、Ｚｒ＝０．５２モル、Ｔｉ＝０．４８モルとなるように、ボールミルで湿式混合してなる混合粉を、８００℃で５時間、焼成した後、解砕処理したものを用いた。 [Preparation of piezoelectric film]
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.
・PZT particles・・・・・・・・・・300 parts by mass ・Cyanoethylated PVA・・・・・・・・30 parts by mass ・DMF・・・・・・・・・・・・70 parts by mass The PZT particles are composed of powders of Pb oxide, Zr oxide and Ti oxide, which are the main components, so that Zr = 0.52 mol and Ti = 0.48 mol with respect to Pb = 1 mol. Mixed powder obtained by wet-mixing in a ball mill was fired at 800° C. for 5 hours and then pulverized.
一方、厚さ４μｍのＰＥＴフィルムに、厚さ２０ｎｍの銅薄膜を真空蒸着してなるシート状物を、２枚、用意した。すなわち、本例においては、第１電極層および第２電極層は、厚さ２０ｎｍの銅蒸着薄膜であり、第１保護層および第２保護層は、厚さ４μｍのＰＥＴフィルムとなる。
１枚のシート状物の銅薄膜（第２電極層）の上に、スライドコーターを用いて、先に調製した圧電体層を形成するための塗料を塗布した。
次いで、シート状物に塗料を塗布した物を、１２０℃のホットプレート上で加熱乾燥することでＤＭＦを蒸発させた。これにより、ＰＥＴ製の第２保護層の上に銅製の第２電極層を有し、その上に、厚さが５０μｍの圧電体層（高分子複合圧電体層）を有する積層体を作製した。 On the other hand, 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 μm. 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 μm-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.
Next, the sheet-like material coated with the paint was dried by heating on a hot plate at 120° C. to evaporate the DMF. Thus, 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 μm thereon was produced. .
１枚のシート状物の銅薄膜（第２電極層）の上に、スライドコーターを用いて、先に調製した圧電体層を形成するための塗料を塗布した。
次いで、シート状物に塗料を塗布した物を、１２０℃のホットプレート上で加熱乾燥することでＤＭＦを蒸発させた。これにより、ＰＥＴ製の第２保護層の上に銅製の第２電極層を有し、その上に、厚さが５０μｍの圧電体層（高分子複合圧電体層）を有する積層体を作製した。 On the other hand, 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 μm. 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 μm-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.
Next, the sheet-like material coated with the paint was dried by heating on a hot plate at 120° C. to evaporate the DMF. Thus, 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 μm thereon was produced. .
作製した圧電体層（積層体）に、加熱ローラ対を用いてカレンダー処理を施した。加熱ローラ対の温度は１００℃とした。
カレンダー処理を行った後、作製した圧電体層を、厚さ方向に分極処理した。 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.
After the calendering treatment, the produced piezoelectric layer was subjected to a polarization treatment in the thickness direction.
カレンダー処理を行った後、作製した圧電体層を、厚さ方向に分極処理した。 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.
After the calendering treatment, the produced piezoelectric layer was subjected to a polarization treatment in the thickness direction.
もう一枚のシート状物を、銅薄膜（第１電極層）を圧電体層に向けて、積層体に積層した。
次いで、積層体とシート状物との積層体を、加熱ローラ対を用いて、温度１２０℃で熱圧着することで、圧電体層と第１電極層とを接着して、図４に示すような圧電フィルムを作製した。 Another sheet was laminated on the laminate with the copper thin film (first electrode layer) facing the piezoelectric layer.
Next, 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.
次いで、積層体とシート状物との積層体を、加熱ローラ対を用いて、温度１２０℃で熱圧着することで、圧電体層と第１電極層とを接着して、図４に示すような圧電フィルムを作製した。 Another sheet was laminated on the laminate with the copper thin film (first electrode layer) facing the piezoelectric layer.
Next, 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.
［実施例１］
作製した圧電フィルムを２０×２５ｃｍの矩形に切断した。
この圧電フィルムを、図１０に示すように、貼着層を設けて、圧電フィルムを折り返し、ローラで押圧して貼着することを、２５ｃｍの方向に５ｃｍ間隔で繰り返した。これにより、圧電フィルムを、５層、積層し、かつ、隣接して積層された圧電フィルムを貼着してなる、平面形状が２０×５ｃｍの図２に示すような圧電素子を作製した。従って、圧電素子は、長さが２０ｃｍの辺が、稜線（折り返し線）となる。
貼着層は、熱可塑性樹脂を用いた。
ローラは、長さが２０ｃｍ以上のものを用い、稜線方向の全域を押圧するように、折り返し方向に移動しつつ圧電フィルムの押圧および貼着を行った。ローラーは、熱可塑性樹脂が溶融する温度以上に加熱した。
なお、ローラによる押圧は、途中で、一部、押圧力を、若干、弱くした。押圧力を弱くする位置は、全ての層で同じ位置とした。 [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.
In addition, 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.
作製した圧電フィルムを２０×２５ｃｍの矩形に切断した。
この圧電フィルムを、図１０に示すように、貼着層を設けて、圧電フィルムを折り返し、ローラで押圧して貼着することを、２５ｃｍの方向に５ｃｍ間隔で繰り返した。これにより、圧電フィルムを、５層、積層し、かつ、隣接して積層された圧電フィルムを貼着してなる、平面形状が２０×５ｃｍの図２に示すような圧電素子を作製した。従って、圧電素子は、長さが２０ｃｍの辺が、稜線（折り返し線）となる。
貼着層は、熱可塑性樹脂を用いた。
ローラは、長さが２０ｃｍ以上のものを用い、稜線方向の全域を押圧するように、折り返し方向に移動しつつ圧電フィルムの押圧および貼着を行った。ローラーは、熱可塑性樹脂が溶融する温度以上に加熱した。
なお、ローラによる押圧は、途中で、一部、押圧力を、若干、弱くした。押圧力を弱くする位置は、全ての層で同じ位置とした。 [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.
In addition, 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.
［実施例２および比較例１］
圧電素子の積層時において、ローラによる押圧力、および、押圧力を弱める位置を変更した以外は、実施例１と同様に圧電素子を作製した。 [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.
圧電素子の積層時において、ローラによる押圧力、および、押圧力を弱める位置を変更した以外は、実施例１と同様に圧電素子を作製した。 [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.
［最短距離Ｌおよび最厚部の決定］
作製した圧電素子において、図９に示すように、稜線方向において、稜線方向の中心に中心測定線ｘ１を設定し、端部から内側に１ｃｍの位置に測定線ｘ２および測定線ｘ３を設定し、中心測定線ｘ１と測定線ｘ２との中間に測定線ｘ４を、中心測定線ｘ１と測定線ｘ３との中間に測定線ｘ５を、それぞれ設定した。
各測定線において、輪郭形状測定器（ミツトヨ社製、ＣＶ－３０００）を用いて表面形状を測定し、最高点の位置を検出した。各測定線毎に、最高点と圧電素子の稜線との最短距離を測定し、その平均値を求めた。この平均値を、圧電素子における、稜線と最厚部との最短距離Ｌとした。
また、折り返し方向に、稜線から最短距離Ｌだけ離れた稜線方向の位置を、圧電素子における最厚部とした。
結果を下記の表に示す。 [Determination of Shortest Distance L and Thickest Part]
In the manufactured piezoelectric element, as shown in FIG. 9, in the direction of the ridgeline, a central measurement line x1 is set at the center of the ridgeline direction, and measurement lines x2 and x3 are set atpositions 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.
On each measurement line, 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.
In addition, 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.
作製した圧電素子において、図９に示すように、稜線方向において、稜線方向の中心に中心測定線ｘ１を設定し、端部から内側に１ｃｍの位置に測定線ｘ２および測定線ｘ３を設定し、中心測定線ｘ１と測定線ｘ２との中間に測定線ｘ４を、中心測定線ｘ１と測定線ｘ３との中間に測定線ｘ５を、それぞれ設定した。
各測定線において、輪郭形状測定器（ミツトヨ社製、ＣＶ－３０００）を用いて表面形状を測定し、最高点の位置を検出した。各測定線毎に、最高点と圧電素子の稜線との最短距離を測定し、その平均値を求めた。この平均値を、圧電素子における、稜線と最厚部との最短距離Ｌとした。
また、折り返し方向に、稜線から最短距離Ｌだけ離れた稜線方向の位置を、圧電素子における最厚部とした。
結果を下記の表に示す。 [Determination of Shortest Distance L and Thickest Part]
In the manufactured piezoelectric element, as shown in FIG. 9, in the direction of the ridgeline, a central measurement line x1 is set at the center of the ridgeline direction, and measurement lines x2 and x3 are set at
On each measurement line, 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.
In addition, 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.
［最厚部および折り返し部の厚さの測定］
作製した圧電素子において、決定した最厚部の厚さＴ１、および、折り返し部の厚さＴ２を測定した。なお、折り返し部の厚さは、圧電フィルムの両端の貼着層の端部の位置における圧電素子の両表面の、積層方向の間隔である。
なお、最厚部および折り返し部の厚さの測定は、共に、設定した中心測定線ｘ１、および、測定線x２～x５において行い、その平均値を、最厚部の厚さＴ１、および、折り返し部の厚さＴ２とした
最厚部および折り返し部の厚さの測定は、φ２ｍｍのフラットタイプの測定子を用いて、デジマチックインジケータ（ミツトヨ社製、ＩＤ－Ｓ１１２Ｘ）によって行った。
結果を下記の表に示す。 [Measurement of Thickness of Thickest Part and Folded Part]
In the manufactured piezoelectric element, 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 φ2 mm flat-type probe and a digimatic indicator (ID-S112X manufactured by Mitutoyo Co., Ltd.).
Results are shown in the table below.
作製した圧電素子において、決定した最厚部の厚さＴ１、および、折り返し部の厚さＴ２を測定した。なお、折り返し部の厚さは、圧電フィルムの両端の貼着層の端部の位置における圧電素子の両表面の、積層方向の間隔である。
なお、最厚部および折り返し部の厚さの測定は、共に、設定した中心測定線ｘ１、および、測定線x２～x５において行い、その平均値を、最厚部の厚さＴ１、および、折り返し部の厚さＴ２とした
最厚部および折り返し部の厚さの測定は、φ２ｍｍのフラットタイプの測定子を用いて、デジマチックインジケータ（ミツトヨ社製、ＩＤ－Ｓ１１２Ｘ）によって行った。
結果を下記の表に示す。 [Measurement of Thickness of Thickest Part and Folded Part]
In the manufactured piezoelectric element, 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 φ2 mm flat-type probe and a digimatic indicator (ID-S112X manufactured by Mitutoyo Co., Ltd.).
Results are shown in the table below.
［貼着層の厚さｔの測定］
作製した圧電素子を設定した中心測定線ｘ１、および、測定線x２～x５で切断して、決定した最厚部の断面をＳＥＭで観察した。ＳＥＭ画像から、各断面における、最厚部の各貼着層の厚さを測定した。
全ての最厚部の貼着層の厚さを平均して、圧電素子における最厚部における貼着層の厚さｔとした。本例では、貼着層が４層、測定線が５本であるので、貼着層の厚さｔは、２０か所の貼着層の厚さの平均値である。
結果を下記の表に示す。
なお、貼着層の厚さｔは、後述する評価を行った後に測定した。 [Measurement of thickness t of adhesive layer]
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.
作製した圧電素子を設定した中心測定線ｘ１、および、測定線x２～x５で切断して、決定した最厚部の断面をＳＥＭで観察した。ＳＥＭ画像から、各断面における、最厚部の各貼着層の厚さを測定した。
全ての最厚部の貼着層の厚さを平均して、圧電素子における最厚部における貼着層の厚さｔとした。本例では、貼着層が４層、測定線が５本であるので、貼着層の厚さｔは、２０か所の貼着層の厚さの平均値である。
結果を下記の表に示す。
なお、貼着層の厚さｔは、後述する評価を行った後に測定した。 [Measurement of thickness t of adhesive layer]
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.
［評価］
＜破断部の検出＞
温度が２３℃、相対湿度が４０％の環境下において、作製した圧電素子の平面形状の全面に、押圧板を用いて１．５Ｍｐａの圧力を１０分間、加えた。
その後、圧電素子における圧電フィルムの折り返し部を、光学顕微鏡によって観察して、圧電体層および電極層における破断部の有無を検出した。
破断部が確認されなかった場合をＡ、
破断部が確認された場合をＢ、と評価した。 [evaluation]
<Detection of broken part>
In an environment of 23° C. temperature and 40% relative humidity, a pressure plate of 1.5 MPa was applied to the entire planar surface of the fabricated piezoelectric element for 10 minutes.
After that, the folded portion of the piezoelectric film in the piezoelectric element was observed with an optical microscope to detect the presence or absence of a broken portion in the piezoelectric layer and the electrode layer.
A when no broken part is confirmed,
A case in which a broken portion was confirmed was evaluated as B.
＜破断部の検出＞
温度が２３℃、相対湿度が４０％の環境下において、作製した圧電素子の平面形状の全面に、押圧板を用いて１．５Ｍｐａの圧力を１０分間、加えた。
その後、圧電素子における圧電フィルムの折り返し部を、光学顕微鏡によって観察して、圧電体層および電極層における破断部の有無を検出した。
破断部が確認されなかった場合をＡ、
破断部が確認された場合をＢ、と評価した。 [evaluation]
<Detection of broken part>
In an environment of 23° C. temperature and 40% relative humidity, a pressure plate of 1.5 MPa was applied to the entire planar surface of the fabricated piezoelectric element for 10 minutes.
After that, the folded portion of the piezoelectric film in the piezoelectric element was observed with an optical microscope to detect the presence or absence of a broken portion in the piezoelectric layer and the electrode layer.
A when no broken part is confirmed,
A case in which a broken portion was confirmed was evaluated as B.
＜ＥＳＲの測定＞
上述した押圧を行った後、圧電素子に関して、Ａｇｉｌｅｎｔ社製のインピーダンスアナライザー４２９４Ａを用いて、測定周波数１０ｋＨｚにおけるＥＳＲ（等価直列抵抗)を測定した。
結果を下記の表に示す。 <Measurement of ESR>
After performing the pressing described above, the ESR (equivalent series resistance) at a measurement frequency of 10 kHz was measured for the piezoelectric element using an impedance analyzer 4294A manufactured by Agilent.
Results are shown in the table below.
上述した押圧を行った後、圧電素子に関して、Ａｇｉｌｅｎｔ社製のインピーダンスアナライザー４２９４Ａを用いて、測定周波数１０ｋＨｚにおけるＥＳＲ（等価直列抵抗)を測定した。
結果を下記の表に示す。 <Measurement of ESR>
After performing the pressing described above, the ESR (equivalent series resistance) at a measurement frequency of 10 kHz was measured for the piezoelectric element using an impedance analyzer 4294A manufactured by Agilent.
Results are shown in the table below.
表に示されるように、圧電フィルムを折り返して積層し、隣接する圧電フィルムを貼着層で貼着した圧電素子において、稜線（折り返し部の端部）と圧電素子の最厚部との最短距離Ｌが、最厚部における貼着層の厚さｔの５０倍以上（Ｌ≧５０＊ｔ）である本発明の圧電素子は、平面形状の全面に圧力を加えられても、折り返し部において圧電体層および電極層の破断を生じていない。従って、本発明の圧電素子は、圧電スピーカーを構成するために振動板に押圧／貼着された際にも、折り返し部の圧電体層および電極層に破断を生じることはなく、目的とする音圧の音声を出力することができる。
また、折り返し部の厚さＴ２に対する最厚部の厚さＴ１が、好ましい範囲である１１５％以上である実施例１は、これを満たさない実施例２に比して、押圧後のＥＳＲが低い。従って、実施例１の圧電素子は、圧電スピーカーを構成するために振動板に押圧／貼着された後に、より安定的で、効率の良い駆動が可能である。
これに対して、最短距離Ｌが、貼着層の厚さｔの５０倍未満である比較例１の圧電素子は、平面形状の全面に圧力を加えられた際に、折り返し部の圧電フィルムが強い面圧を受けたと考えられ、折り返し部において、圧電体層および電極層の破断が生じている。そのため、この圧電素子が圧電スピーカーを構成するために振動板に押圧／貼着された際には、折り返し部の圧電体層および電極層に破断を生じ、目的とする音圧の音声を出力することができない可能性がある。また、比較例１の圧電素子は、本発明品に比して押圧後のＥＳＲが高い。そのため、比較例１の圧電素子は、圧電スピーカーを構成するために振動板に押圧／貼着された後に、駆動が不安定で、また、効率も悪くなる可能性がある。
以上の結果より、本発明の効果は明らかである。 As shown in the table, 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.
In addition, 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.
On the other hand, in 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.
また、折り返し部の厚さＴ２に対する最厚部の厚さＴ１が、好ましい範囲である１１５％以上である実施例１は、これを満たさない実施例２に比して、押圧後のＥＳＲが低い。従って、実施例１の圧電素子は、圧電スピーカーを構成するために振動板に押圧／貼着された後に、より安定的で、効率の良い駆動が可能である。
これに対して、最短距離Ｌが、貼着層の厚さｔの５０倍未満である比較例１の圧電素子は、平面形状の全面に圧力を加えられた際に、折り返し部の圧電フィルムが強い面圧を受けたと考えられ、折り返し部において、圧電体層および電極層の破断が生じている。そのため、この圧電素子が圧電スピーカーを構成するために振動板に押圧／貼着された際には、折り返し部の圧電体層および電極層に破断を生じ、目的とする音圧の音声を出力することができない可能性がある。また、比較例１の圧電素子は、本発明品に比して押圧後のＥＳＲが高い。そのため、比較例１の圧電素子は、圧電スピーカーを構成するために振動板に押圧／貼着された後に、駆動が不安定で、また、効率も悪くなる可能性がある。
以上の結果より、本発明の効果は明らかである。 As shown in the table, 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.
In addition, 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.
On the other hand, in 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.
圧電スピーカー等として、各種の用途に好適に利用可能である。
It can be suitably used for various purposes as a piezoelectric speaker.
１０ 圧電素子
１２ 圧電フィルム
２０，６８ 貼着層
２６ 圧電体層
２８ 第１電極層
３０ 第２電極層
３２ 第１保護層
３４ 第２保護層
３８ 高分子マトリックス
４０ 圧電体粒子
４２ａ，４２ｂ シート状物
４６ 積層体
５０ ローラ
６０ 圧電スピーカー
６２ 振動板
７２ 第１引出配線
７４ 第２引出配線
Ｍ 最厚部 REFERENCE SIGNSLIST 10 piezoelectric element 12 piezoelectric film 20, 68 adhesive layer 26 piezoelectric layer 28 first electrode layer 30 second electrode layer 32 first protective layer 34 second protective layer 38 polymer matrix 40 piezoelectric particles 42a, 42b sheet-like object 46 Laminated body 50 Roller 60 Piezoelectric speaker 62 Diaphragm 72 First lead wire 74 Second lead wire M Thickest part
１２ 圧電フィルム
２０，６８ 貼着層
２６ 圧電体層
２８ 第１電極層
３０ 第２電極層
３２ 第１保護層
３４ 第２保護層
３８ 高分子マトリックス
４０ 圧電体粒子
４２ａ，４２ｂ シート状物
４６ 積層体
５０ ローラ
６０ 圧電スピーカー
６２ 振動板
７２ 第１引出配線
７４ 第２引出配線
Ｍ 最厚部 REFERENCE SIGNS
Claims (8)
- 可撓性を有する圧電フィルムを折り返すことで、前記圧電フィルムを複数層、積層した圧電素子において、
積層されて隣接する前記圧電フィルムを貼着する貼着層を有し、
前記圧電素子の最厚部における前記貼着層の厚さをｔ、前記圧電フィルムの折り返し部の端部と前記圧電素子の最厚部との最短距離をＬとした際に、『Ｌ≧５０＊ｔ』を満たすことを特徴とする圧電素子。 By folding a flexible piezoelectric film, in a piezoelectric element in which a plurality of layers of the piezoelectric film are laminated,
having an adhesion layer for adhering 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. - 前記圧電フィルムの積層方向から見た際に矩形状であり、
前記矩形の長辺と、前記圧電フィルムの折り返し線とが一致する、請求項１に記載の圧電素子。 It has a rectangular shape when viewed from the lamination direction of the piezoelectric film,
2. The piezoelectric element according to claim 1, wherein the long sides of the rectangle are aligned with folding lines of the piezoelectric film. - 前記最厚部の厚さが、前記圧電フィルムの折り返し部の厚さの１１５％以上である、請求項１に記載の圧電素子。 The piezoelectric element according to claim 1, wherein the thickness of the thickest portion is 115% or more of the thickness of the folded portion of the piezoelectric film.
- 前記圧電フィルムが、圧電体層と、前記圧電体層の両面に設けられた電極層と、前記電極層を覆って設けられた保護層と、を有する、請求項１に記載の圧電素子。 2. The piezoelectric element according to claim 1, wherein the piezoelectric film has a piezoelectric layer, electrode layers provided on both sides of the piezoelectric layer, and a protective layer covering the electrode layer.
- 前記圧電体層が、高分子材料中に圧電体粒子を有する高分子複合圧電体である、請求項４に記載の圧電素子。 The piezoelectric element according to claim 4, wherein the piezoelectric layer is a polymeric composite piezoelectric body having piezoelectric particles in a polymer material.
- 前記高分子材料が、シアノエチル基を有する、請求項５に記載の圧電素子。 The piezoelectric element according to claim 5, wherein the polymeric material has a cyanoethyl group.
- 前記高分子材料が、シアノエチル化ポリビニルアルコールである、請求項６に記載の圧電素子。 The piezoelectric element according to claim 6, wherein the polymeric material is cyanoethylated polyvinyl alcohol.
- 振動板に、請求項１～７のいずれか１項に記載の圧電素子を貼着してなる、圧電スピーカー。 A piezoelectric speaker comprising a diaphragm and the piezoelectric element according to any one of claims 1 to 7 attached thereto.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2020196850A1 (en) * | 2019-03-28 | 2020-10-01 | 富士フイルム株式会社 | Piezoelectric film, layered piezoelectric element, and electroacoustic transducer |
| WO2020241049A1 (en) * | 2019-05-27 | 2020-12-03 | ソニー株式会社 | Audio reproduction apparatus and audio device |
| CN113066924A (en) * | 2021-03-18 | 2021-07-02 | 业成科技（成都）有限公司 | Thin film piezoelectric sensing element and manufacturing method thereof, sensing device and terminal |
| WO2021200455A1 (en) * | 2020-03-31 | 2021-10-07 | 富士フイルム株式会社 | Layered piezoelectric element and electroacoustic transducer |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2020196850A1 (en) * | 2019-03-28 | 2020-10-01 | 富士フイルム株式会社 | Piezoelectric film, layered piezoelectric element, and electroacoustic transducer |
| WO2020241049A1 (en) * | 2019-05-27 | 2020-12-03 | ソニー株式会社 | Audio reproduction apparatus and audio device |
| WO2021200455A1 (en) * | 2020-03-31 | 2021-10-07 | 富士フイルム株式会社 | Layered piezoelectric element and electroacoustic transducer |
| CN113066924A (en) * | 2021-03-18 | 2021-07-02 | 业成科技（成都）有限公司 | Thin film piezoelectric sensing element and manufacturing method thereof, sensing device and terminal |
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