JP5157324B2 - Piezoelectric structure and speaker equipped with the same - Google Patents

Description

  The present invention generally relates to a piezoelectric structure and a speaker including the same, and more particularly to a transparent piezoelectric structure and a speaker including the same.

  Conventionally, there has been a form of a speaker that can add a speaker function to an article while various articles such as windows, doors, walls, and other buildings, furniture, decorations, etc. have their original functions. It is being considered. As one form of such a speaker, a thin-film transparent speaker has been proposed.

  For example, Japanese Patent Laid-Open No. 4-70100 (Patent Document 1) is configured by providing a transparent piezoelectric ceramic such as PLZT with transparent electrodes on both surfaces of a glass or plastic thin film diaphragm. Unimorph type or bimorph type transparent speakers have been proposed.

Further, for example, Japanese Patent Laid-Open No. 2003-244792 (Patent Document 2) proposes a piezoelectric film speaker installed in a portable information terminal. The piezoelectric film diaphragm constituting the piezoelectric film speaker is formed by forming transparent electrodes on both front and back surfaces of a transparent and elastic flexible piezoelectric film. Polyvinylidene fluoride (PVDF) is used as the flexible piezoelectric film.
JP-A-4-70100 JP 2003-244792 A

  However, although the transparent speaker proposed in Japanese Patent Laid-Open No. 4-70100 (Patent Document 1) has transparency, it uses a piezoelectric member made of ceramic or single crystal, so it has low flexibility and is a transparent speaker. It is difficult to form a curved surface by itself. For this reason, for example, when a transparent speaker is pasted on the display screen of an electronic device such as a mobile phone or a portable game machine, the piezoelectric member may be destroyed. In addition, when the piezoelectric member is formed of PLZT, PLZT itself is not colorless and transparent, and thus the above-described transparent speaker has a problem of poor transparency.

  On the other hand, although the piezoelectric film speaker proposed in Japanese Patent Application Laid-Open No. 2003-244792 (Patent Document 2) has flexibility, it uses milky white PVDF as the piezoelectric film, so the piezoelectric film is formed very thin. Even so, there is a problem that transparency is inferior. For this reason, when the above piezoelectric film speaker is pasted on the display screen of an electronic device such as a mobile phone or a portable game machine, the display performance of the display screen may be deteriorated.

  Accordingly, an object of the present invention is to provide a piezoelectric structure capable of having both good flexibility and good transparency to visible light, and a speaker including the piezoelectric structure.

  The piezoelectric structure according to the present invention includes a resin layer having main surfaces facing each other on both sides, and a transparent electrode layer arranged so as to sandwich the main surfaces on both sides of the resin layer. The resin layer includes a transparent resin portion and a plurality of columnar dispersion portions exhibiting piezoelectricity dispersed in the resin portion. The dispersed portion is oriented and dispersed in the resin portion so that the major axis direction is substantially parallel to the normal direction of the resin portion, has a diameter of 400 nm or less, and is polarized in the major axis direction. .

  In the piezoelectric structure according to the present invention, the portion serving as the base material in which the dispersed portion exhibiting piezoelectricity is disposed is the resin portion. As a result, the piezoelectric structure of the present invention has flexibility. For example, a speaker including the piezoelectric structure of the present invention is pasted on the display screen of an electronic device such as a mobile phone or a portable game machine. In such a case, the piezoelectric member is not destroyed.

  In the piezoelectric structure of the present invention, the dispersed portion having a diameter of 400 nm or less is dispersed in the transparent resin portion so that the major axis direction is substantially parallel to the normal direction of the resin portion. Yes. Thus, since the diameter of the dispersed portion dispersed in the transparent resin portion is smaller than about 400 nm which is the lower limit of the wavelength of visible light, the resin layer itself may have good transparency to visible light. it can. Thereby, for example, when a speaker having the piezoelectric structure of the present invention is pasted on a display screen of an electronic device such as a mobile phone or a portable game machine, the display performance of the display screen is not deteriorated. .

  Therefore, it is possible to obtain a piezoelectric structure that can have both good flexibility and good transparency to visible light.

  In the piezoelectric structure of the present invention, it is preferable that the resin layers and the electrode layers are alternately laminated.

  With such a configuration, a piezoelectric structure having a multilayer structure can be obtained. Therefore, when a speaker is configured using the piezoelectric structure of the present invention, the strength of the speaker can be improved.

  A speaker according to one aspect of the present invention includes a piezoelectric structure having the above characteristics.

  The speaker according to the present invention may include a transparent base material having a main surface, and the piezoelectric structure having the above characteristics may be bonded onto the main surface of the base material.

  By comprising in this way, a unimorph type speaker can be constituted.

  Further, the speaker of the present invention may be configured to include a plurality of stacked piezoelectric structures.

  With this configuration, a bimorph type speaker can be configured.

  Further, in the speaker of the present invention, the piezoelectric structure may have a main surface, and the plurality of piezoelectric structures may be configured to be joined so that the main surfaces are connected to form a plurality of vibration regions. .

  With this configuration, a speaker having a plurality of separated vibration regions can be configured. The plurality of vibration regions do not necessarily have different resonance frequencies. For example, a stereo speaker can be configured by forming two vibration regions having the same characteristics.

  In this case, the plurality of vibration regions may have different resonance frequencies.

  With this configuration, it is possible to configure a speaker having a plurality of vibration regions having different frequency characteristics.

  Furthermore, in this case, the plurality of vibration regions may have different areas.

  In this way, a speaker having a plurality of vibration regions with different frequency characteristics can be configured with a simple configuration.

  In the speaker according to the present invention, it is preferable that an attenuation region for attenuating vibrations of a plurality of adjacent vibration regions is provided at a boundary between the plurality of vibration regions.

  With this configuration, it is possible to improve sound separability in a speaker having a plurality of vibration regions.

  As described above, according to the present invention, it is possible to obtain a piezoelectric structure that can have both good flexibility and good transparency to visible light, and a speaker including the piezoelectric structure.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a partial perspective view showing a resin layer in a piezoelectric structure as one embodiment of the present invention. FIG. 2 is a partial cross-sectional view as seen from the direction along line II-II in FIG.

  As shown in FIG. 1 and FIG. 2, a plate-shaped resin layer 10 as a piezoelectric composite layer has a columnar single crystal body 1 as a large number of columnar dispersed portions and a large number of columnar single crystal bodies 1 arranged therein. And a transparent resin portion 2 as a base material. The plate-like resin layer 10 has main surfaces facing each other on both sides. Although not shown, the transparent electrode layer is disposed so as to sandwich the main surfaces on both sides of the resin layer 10 as described later, whereby the piezoelectric structure of the present invention is configured. Many columnar single crystals 1 are polarized in the long axis direction and exhibit piezoelectricity when a predetermined voltage is applied to the electrode layer. A large number of columnar single crystals 1 are dispersed in the resin portion 2 so that the major axis direction is substantially parallel to the normal direction of the resin portion 2. In other words, a large number of columnar single crystals 1 are aligned in the resin thin film, that is, a large number of columnar single crystals 1 are erected in the thickness direction of the resin portion 2, and the resin portion 2. They are arranged in a dispersed manner at a predetermined interval. Each of the columnar single crystals 1 has a diameter of 400 nm or less.

  Since it is configured in this way, the resin layer 1 can obtain a high piezoelectric constant by the columnar single crystal 1 dispersed in the resin portion 2 even if the resin portion 2 itself does not have piezoelectricity.

  Moreover, the part used as the base material in which the columnar single crystal body 1 which shows piezoelectricity is arrange | positioned is the resin part 2. FIG. For this reason, since the resin layer 1 has flexibility, for example, when a speaker provided with the piezoelectric structure of the present invention is pasted on the display screen of an electronic device such as a mobile phone or a portable game machine, The member showing piezoelectricity is not destroyed.

  Furthermore, in the piezoelectric structure of the present invention, the columnar single crystal 1 having a diameter of 400 nm or less is oriented so that the major axis direction is substantially parallel to the normal direction of the resin portion 2, and the transparent resin portion 2 Distributed in. Thus, since the diameter of the columnar crystal 1 dispersed in the transparent resin portion 2 is smaller than about 400 nm which is the lower limit of the wavelength of visible light, the resin layer 10 itself has good transparency to visible light. Can have. That is, as shown in FIG. 2, visible light can pass through the resin portion 2 as indicated by an arrow P. Preferably, when the diameter of the columnar crystal body 1 is 100 nm or less, the visible light scattering is hardly caused by the difference in refractive index between the columnar single crystal body 1 and the resin portion 2. For this reason, if the transparency of the resin part 2 is high, the transparency of the resin layer 10 itself can be increased. Thereby, for example, when a speaker having the piezoelectric structure of the present invention is pasted on a display screen of an electronic device such as a mobile phone or a portable game machine, the display performance of the display screen is not deteriorated. .

  Therefore, it is possible to obtain a piezoelectric structure that can have both good flexibility and good transparency to visible light.

  The resin layer 10 as shown in FIGS. 1 and 2 is manufactured as follows, for example.

  A large number of columnar single crystals are mixed in a liquid resin that is not solidified, and the columnar single crystals are dispersed in the liquid resin using a dispersing material. Thereafter, by applying a magnetic field from the outside, the columnar single crystal is oriented upright in the magnetic field direction.

  In this case, even if the single crystal other than the cubic crystal is a paramagnetic substance or a weak magnetic substance, it has a magnetic anisotropy in the crystal, so that it can be oriented in the magnetic field direction by applying a strong magnetic field from the outside. it can. Since a single crystal body exhibiting piezoelectricity is basically not a cubic crystal, it can be always oriented by the above method. In addition, since the columnar single crystal has a large shape anisotropy, it becomes easier to be oriented by applying a strong magnetic field.

  As a material for the resin portion 2, it is preferable to use a resin such as acrylic, polycarbonate, acrylonitrile styrene, polystyrene, nylon 12, or polyether sulfone. These resins are excellent in transparency, have no discoloration due to sunlight, are very small, and have a high flexural modulus. Therefore, high sound quality can be expected when a speaker is configured.

As a material for the columnar single crystal body 1, it is preferable to use relaxor, BaTiO ₃ , BaTi ₂ O ₅ or the like.

When a relaxer is used as the material of the columnar single crystal body 1, since the relaxer is generally a single crystal having a huge piezoelectric constant, for example, a piezoelectric constant two to four times that of lead zirconate titanate (PZT) is obtained. be able to. Further, by using a relaxer as the material of the columnar single crystal body 1, a piezoelectric composite layer having a large piezoelectric constant can be obtained. The relaxer can be obtained by using a rapid cooling method. As the relaxer, PMN-PT (Pb (Mg _1/3 Nb _2/3 ) O ₃ -PbTiO ₃ ), PZN-PT (Pb (Zn _1/3 Nb _2/3 ) O ₃ -PbTiO ₃ ), PNN- At least one of PT (Pb (Ni _1/3 Nb _2/3 ) O ₃ —PbTiO ₃ ) or a mixture thereof may be used. Among these materials, PMN-PT single crystals are relatively easy to obtain, and the Curie temperature is relatively low at 155 ° C. When polyethersulfone (PES) is used as the material constituting the resin portion 2, the temperature of the single crystal of PMN-PT is set to be equal to or higher than the Curie temperature during the polarization treatment because the heat distortion temperature of PES is relatively high at 200 ° C. However, the resin portion 2 is not deformed. On the other hand, if the resin portion 2 is made of a material having a low thermal deformation temperature, the temperature of the single crystal of PMN-PT cannot be raised to the Curie temperature, but can be polarized by increasing the voltage in the polarization process. it can.

By using a single crystal of BaTiO ₃ or BaTi ₂ O ₅ as the material of the columnar single crystal body 1, a lead-free transparent speaker can be configured. In particular, since BaTi ₂ O ₅ has a larger piezoelectric constant than BaTiO ₃ and is colorless and transparent, it is advantageous for constituting a transparent speaker.

  FIG. 3 is a partial cross-sectional view of a resin layer in a piezoelectric structure as another embodiment of the present invention as seen from the direction along line II-II in FIG.

  As shown in FIG. 3, the columnar single crystal may not penetrate through the resin layer 10 as in the columnar single crystal 1 a and may not be exposed on the main surfaces on both sides of the resin layer 10 facing each other. Good. Further, the columnar single crystal may be exposed only on one main surface of the resin layer 10 as in the columnar single crystal 1b, and the columnar single crystal in the resin layer 10 as in the columnar single crystal 1c. It may be exposed only on the other main surface. As shown in FIG. 3, when the columnar single crystals 1 a to 1 c do not penetrate the resin layer 10, as compared to the case where the columnar single crystals 1 penetrate the resin layer 10 as shown in FIG. 2. The electric field in the columnar single crystal is reduced. Therefore, in such a case, since the electrostrictive effect of the columnar single crystal is reduced, it is preferable to increase the content ratio of the columnar single crystals 1a to 1c in the resin layer 10. Thereby, even when the columnar single crystal does not penetrate the resin layer, a sufficient piezoelectric constant can be obtained. In order to maintain the transparency of the resin layer 10 as a whole, the density of the columnar single crystals is preferably limited so that the distance between the columnar single crystals is not too close. It is preferable that the distance be larger than approximately twice the diameter of the columnar single crystal.

  FIG. 4 is a cross-sectional view showing a multilayered piezoelectric structure as one embodiment of the present invention.

  As shown in FIG. 4, in the piezoelectric structure 100, the transparent electrode layers 21 and 22 are disposed so as to sandwich the main surfaces on both sides of the resin layers 11 and 12 as piezoelectric composite layers. By applying a predetermined voltage between the electrode layers 21 and 22, the resin layers 11 and 12 expand and contract. At this time, the resin layers 11 and 12 are polarized in opposite directions in order to align the expansion and contraction directions of the resin layers 11 and 12. That is, the columnar single crystal dispersed in the resin layer 11 and the columnar single crystal dispersed in the resin layer 12 are polarized in opposite directions. With this configuration, by applying a predetermined voltage between the electrode layers 21 and 22, the piezoelectric structure 100 can be expanded and contracted in the plane direction as a unit.

  As described above, in the piezoelectric structure 100, since the resin layers 11 and 12 and the electrode layers 21 and 22 are alternately laminated, a piezoelectric structure having a multilayer structure can be obtained. When a speaker is configured using 100, the strength of the speaker can be improved.

  As a material of the transparent electrode layers 21 and 22, ITO, IZO (registered trademark), ZnO, or the like can be used. Since ITO or IZO contains indium which is a rare metal as a constituent metal, it may be expensive, so it is preferable to use ZnO. In addition, ZnO has been conventionally considered to be difficult to form on a resin because the formation temperature is 200 ° C. or higher, but as disclosed in International Publication No. WO2007 / 080738, Since it becomes possible to form at normal temperature, it is suitable for forming on the surface of the resin layers 11 and 12.

  FIG. 5 is a partial cross-sectional view schematically showing the expansion and contraction operation of the resin layer.

  As shown in FIGS. 5A to 5B, by applying a voltage to the transparent electrode layer arranged so as to sandwich both surfaces of the resin layer 10, the resin layer 10 is arranged in the thickness direction as indicated by arrows. The resin layer 10 stretches in the plane direction, that is, the resin layer 10 extends in the plane direction so that the interval between the columnar single crystals 1 increases as indicated by arrows. And the reverse expansion / contraction operation | movement is performed as shown to (A) from (B) of FIG. By repeating such an operation, the resin layer 10 expands and contracts in the surface direction. The function of the speaker is realized using this expansion and contraction motion.

  FIG. 6 is a sectional view conceptually showing a unimorph type speaker constituted by using the piezoelectric structure of the present invention.

  As shown in FIG. 6, a unimorph type speaker unit 1000 is configured by joining a piezoelectric structure 100 on a main surface of a transparent substrate 200 as a transparent base material having a main surface. The transparent substrate 200 is formed of, for example, a transparent resin. In this case, due to the expansion and contraction of the piezoelectric structure 100, the entire unimorph type speaker unit 1000 undergoes bending vibration.

  FIG. 7 is a sectional view conceptually showing a bimorph type speaker constituted by using the piezoelectric structure of the present invention.

  As shown in FIG. 7, a plurality of piezoelectric structures 110 and 120 are laminated and bonded to each other to form a bimorph type speaker unit 1100. In this case, the bimorph type loudspeaker unit 1100 as a whole vibrates by bending when the expansion and contraction operations of the plurality of piezoelectric structures 110 and 120 are driven in opposite directions. In FIG. 7, the plurality of piezoelectric structures 110 and 120 are directly joined, but a resin layer or the like may be interposed between the plurality of piezoelectric structures 110 and 120.

  FIG. 8 is a partial cross-sectional view schematically showing the expansion / contraction operation of the piezoelectric structure constituting the bimorph type speaker unit.

  As shown in FIG. 8A, the piezoelectric structure 110 constituting the bimorph type speaker unit 1100 extends as indicated by an arrow, and the piezoelectric structure 120 contracts as indicated by an arrow. Then, the reverse expansion / contraction operation is performed as shown in FIG. By repeating such an operation, the bimorph type speaker unit 1100 expands and contracts in the surface direction. The function of the speaker is realized using this expansion and contraction motion.

  FIG. 9 is a cross-sectional view showing one embodiment of the attenuation region when the speaker unit is composed of a plurality of vibration regions.

  As shown in FIG. 9, when the unimorph type speaker unit 1000 or the bimorph type speaker unit 1100 is composed of a plurality of vibration regions, the vibrations of the adjacent vibration regions are attenuated at the boundaries of the plurality of vibration regions. A groove 1001 is formed as an attenuation region.

  FIG. 10 is a cross-sectional view showing another embodiment of the attenuation region when the speaker unit is composed of a plurality of vibration regions.

  As shown in FIG. 10, when the unimorph type speaker unit 1000 or the bimorph type speaker unit 1100 is composed of a plurality of vibration regions, the vibrations of the adjacent vibration regions are attenuated at the boundaries of the plurality of vibration regions. The attenuation region is provided. Specifically, the attenuation region includes a through hole 1002 and an elastic member 300 such as silicone rubber filled in the through hole 1002.

  FIG. 11 is a cross-sectional view showing still another embodiment of the attenuation region in the case where the speaker unit is composed of a plurality of vibration regions.

  As shown in FIG. 11, when the unimorph type speaker unit 1000 or the bimorph type speaker unit 1100 is composed of a plurality of vibration regions, the vibrations of the adjacent vibration regions are attenuated at the boundaries of the plurality of vibration regions. The attenuation region is provided. Specifically, the attenuation region includes a groove 1001 and an elastic member 310 such as silicone rubber filled in the groove 1001.

  By configuring as shown in FIGS. 9 to 11 as described above, it is possible to improve sound separability in a speaker having a plurality of vibration regions.

  FIG. 12 is a plan view showing a stereo type speaker unit, and FIG. 13 is a cross-sectional view seen from the direction along line XIII-XIII in FIG.

  As shown in FIGS. 12 and 13, a plurality of piezoelectric structures 110 and 120 are bonded to each other with a transparent substrate 200 made of a resin layer or the like interposed therebetween, and a metal or hard metal is surrounded so as to surround the bonded body. A stereo type bimorph type speaker unit 1100 is configured by fixing a frame body 400 made of resin or the like to the transparent substrate 200. Adjacent piezoelectric structures 110 and 110 and adjacent piezoelectric structures 120 and 120 are joined such that their main surfaces are continuous. Attenuation areas for attenuating vibrations of the adjacent vibration areas as necessary at the boundaries between the adjacent piezoelectric structures 110 and 110 and the adjacent piezoelectric structures 120 and 120 as a plurality of vibration areas. Is provided. Specifically, the attenuation region includes a through hole 1002 and an elastic member 300 such as silicone rubber filled in the through hole 1002. In this case, the bimorph type loudspeaker unit 1100 as a whole vibrates by bending when the expansion and contraction operations of the plurality of piezoelectric structures 110 and 120 are driven in opposite directions. In addition, it is possible to improve the separation of left and right sounds in a stereo type speaker. A groove may be formed instead of the through hole 1002, and a rubber resin having a refractive index close to that of the resin part constituting the piezoelectric structure is used as the through hole 1002 or the elastic member 300 filling the groove. The boundary portion may not be noticeable.

  FIG. 14 is a plan view showing a speaker unit as still another embodiment of the present invention.

  As shown in FIG. 14, the speaker unit 1200 may be configured by joining together a plurality of piezoelectric structures 130 having different areas. In this case, the frequency characteristics of each piezoelectric structure 130 can be made different. That is, a speaker having a plurality of vibration regions having different resonance frequencies can be formed by forming a plurality of vibration regions having different areas. For example, a multi-way speaker capable of reproducing from a low sound range to a high temperature range can be configured. The piezoelectric structure 130 generally has a lower resonance frequency when the area is larger. The resonance frequency can also be changed by changing the thickness of the piezoelectric structure 130. In addition, a through hole or a groove may be formed at the boundary between the plurality of piezoelectric structures 130 as necessary. As an elastic member filling the through hole or the groove, a resin portion and a refractive index constituting the piezoelectric structure are used. By using a rubber-based resin close to the boundary, the boundary portion may not be noticeable. By doing in this way, the separability of the frequency characteristic of each piezoelectric structure can be improved.

  As described above, a plurality of piezoelectric structures are joined so that their main surfaces are connected to form a plurality of vibration regions, whereby a speaker having a plurality of separated vibration regions can be configured. In this case, the plurality of vibration regions can be configured as a speaker having a plurality of vibration regions having different frequency characteristics by having different resonance frequencies. Further, in this case, since the plurality of vibration regions have different areas, a speaker having a plurality of vibration regions with different frequency characteristics can be configured with a simple configuration. However, the plurality of vibration regions do not necessarily have different resonance frequencies. For example, by forming two vibration regions having the same characteristics, a stereo type speaker can be configured. Note that, by providing an attenuation region for attenuating vibrations of a plurality of adjacent vibration regions at the boundaries of the plurality of vibration regions, it is possible to improve sound separability in a speaker having a plurality of vibration regions.

  FIG. 15 is a partial cross-sectional view showing a specific configuration of a bimorph type speaker unit as one embodiment of the present invention. FIG. 16 is a diagram showing a relationship between wiring and polarization direction in the bimorph type speaker unit shown in FIG.

  The bimorph type speaker unit 1100 includes a transparent electrode layer 21 so as to sandwich main surfaces on both sides of the resin layers 11 and 12 as piezoelectric composite layers having opposite polarization directions as indicated by arrows in FIG. 22 is joined. A predetermined voltage is applied by connecting the terminal U to the electrode layer 21 and connecting the terminal V to the electrode layer 22. Adjacent resin layers 11 and 11 and adjacent resin layers 12 and 12 are joined so that their main surfaces are continuous. Attenuating regions for attenuating the vibrations of the plurality of adjacent vibration regions are provided at the boundaries between the adjacent resin layers 11 and 11 and the adjacent resin layers 12 and 12 as the plurality of vibration regions. Specifically, the attenuation region includes a through hole and an elastic member 300 such as silicone rubber filled in the through hole. A transparent substrate 200 made of resin or the like is disposed between the piezoelectric structures A and B configured as described above. By applying a predetermined voltage between the electrode layers 21 and 22, each of the piezoelectric structures A and B integrally expands and contracts in the plane direction as shown in FIG. 16, for example, a positive potential is applied to the electrode layer 21. (When the terminal U is positive), when a voltage is applied to the electrode layer 22 so as to have a negative potential (terminal V is negative), the piezoelectric structure A is displaced so as to expand, and the piezoelectric structure B is displaced so as to contract. And extend and contract. When a potential opposite to the above is applied to the electrode layers 21 and 22, the piezoelectric structure B is displaced so as to be extended, and the piezoelectric structure A is displaced so as to be contracted so as to expand and contract. Note that it is only necessary that the extending piezoelectric structure and the contracting piezoelectric structure are laminated with the transparent substrate 200 as a boundary. In the above embodiment, the bimorph type speaker unit 1100 shows the piezoelectric structures A and B composed of the two resin layers 11 and 12, respectively, but the piezoelectric structure is composed of two or more resin layers. May be configured.

  FIG. 17 is a partial cross-sectional view showing a specific configuration of a bimorph type speaker unit as another embodiment of the present invention. FIG. 18 is a diagram showing the relationship between wiring and polarization direction in the bimorph type speaker unit shown in FIG.

  The bimorph type speaker unit 1100 includes a transparent electrode layer 21 so as to sandwich main surfaces on both sides of the resin layers 11 and 12 as piezoelectric composite layers whose polarization directions are opposite to each other as indicated by arrows in FIG. 22 is joined. A predetermined voltage is applied by connecting the terminal U to the electrode layer 21 and connecting the terminal V to the electrode layer 22. Adjacent resin layers 11 and 11 and adjacent resin layers 12 and 12 are joined so that their main surfaces are continuous. Attenuating regions for attenuating the vibrations of the plurality of adjacent vibration regions are provided at the boundaries between the adjacent resin layers 11 and 11 and the adjacent resin layers 12 and 12 as the plurality of vibration regions. Specifically, the attenuation region includes a through hole and an elastic member 300 such as silicone rubber filled in the through hole. The piezoelectric structures A and B configured in this way are disposed on the transparent substrate 200 while being bonded. In this case, the transparent substrate 200 needs to be made of a rubber-based elastic material such as silicone rubber. The elastic member 300 may not be filled. By applying a predetermined voltage between the electrode layers 21 and 22, each of the piezoelectric structures A and B integrally expands and contracts in the plane direction as shown in FIG. 18, for example, a positive potential is applied to the electrode layer 21. (When the terminal U is positive), when a voltage is applied to the electrode layer 22 so as to have a negative potential (terminal V is negative), the piezoelectric structure A is displaced so as to expand, and the piezoelectric structure B is displaced so as to contract. And extend and contract. When a potential opposite to the above is applied to the electrode layers 21 and 22, the piezoelectric structure B is displaced so as to be extended, and the piezoelectric structure A is displaced so as to be contracted so as to expand and contract. In the above embodiment, the bimorph type speaker unit 1100 shows the piezoelectric structures A and B composed of the two resin layers 11 and 12, respectively, but the piezoelectric structure is composed of two or more resin layers. May be configured. Each electrode layer 21, 22 is connected to the electrode terminal of the drive circuit by wire bonding or the like at the end of the transparent substrate 200.

  The bimorph type speaker unit shown in FIGS. 17 to 18 can divide the vibration of each piezoelectric structure more clearly than the bimorph type speaker unit shown in FIGS. When dividing into a low sound part, a middle sound part, and a high sound part, it is desirable to employ the structure of the bimorph type speaker unit shown in FIGS.

  As described above, various types of transparent speakers can be configured by using the piezoelectric structure of the present invention. Such a transparent speaker can be formed by directly pasting on the surface of a display screen of an electronic device such as a mobile phone, a portable game machine, an electronic dictionary, or an electronic notebook, or a display screen of a personal computer, a television, or the like. .

  FIG. 19 is a perspective view showing a mobile phone as one application example of the speaker of the present invention.

  As shown in FIG. 19, the mobile phone 50 includes an operation unit 51 and a display screen unit 52. On the surface of the display screen section 52, the unimorph type speaker 1000 or the bimorph type speaker 1100 of the present invention is directly attached and formed.

  FIG. 20 is a plan view showing a portable game machine as another application example of the present invention.

  As shown in FIG. 20, the portable game machine 60 includes an operation unit 61 and a display screen unit 62. On the surface of the display screen section 52, the unimorph type speaker 1000 or the bimorph type speaker 1100 of the present invention is directly attached and formed.

  In general, in order to make a speaker of high sound quality, it is necessary to enlarge the speaker. However, in the current piezoelectric speaker, there is a limit to increase it due to the limitation of equipment space. By using the piezoelectric structure of the present invention, a speaker can be disposed on the surface of the display screen. For this reason, since the area of the speaker can be increased, not only the sound quality can be improved, but it is not necessary to incorporate the speaker in the device as in the prior art, and the device can be miniaturized. In addition, since new functional parts and the like can be arranged in the portion where the conventional speaker is built, it is possible to increase the functionality of the device.

  Moreover, in the piezoelectric structure of the present invention, an image displayed on a display screen arranged under the speaker can be clearly seen by using a highly transparent resin portion constituting the base of the resin layer. Furthermore, since the speaker of the present invention does not require parts such as an exciter, the entire surface can be made transparent.

  In the piezoelectric structure of the present invention, since the portion constituting the base material is a resin, it is not broken at a normal impact level. For this reason, even if the speaker of the present invention is adopted in a mobile phone or a portable game machine, the possibility of breakage in a normal usage pattern is very small. In addition, since the speaker of the present invention can be bent, it can be applied to a paper display using an organic EL.

  In the piezoelectric structure of the present invention, as a resin part material, when a resin such as acrylic, polycarbonate, acrylonitrile styrene, polystyrene, nylon 12, polyether sulfone is used, these resins are excellent in transparency and discoloration due to sunlight. The speaker of the present invention is preferably applied to devices that may be used outdoors, such as mobile phones and electronic notebooks, because they are not or very small.

  Further, by attaching the speaker of the present invention to a window near a priority seat such as a train or a bus, it becomes easy for elderly people to listen to the in-car broadcast, and the view of the vehicle window is not blocked by the speaker.

  Furthermore, by attaching the speaker of the present invention to the advertisement on the wall, particularly the face of the advertisement on which the person image is arranged, the advertisement contents can be played as sound as if the person image in the advertisement is speaking. It is possible to attract people's interest and increase the advertising effect. In this case, by combining the infrared sensor or Doppler sensor with the speaker of the present invention, the person in the advertisement when the person approaches the advertisement If the image calls (stops), the advertising effect can be further enhanced.

  Since the speaker of the present invention can be directly attached to the surface of a pachinko machine or a pachislot machine, powerful sound can be produced when sound is emitted from the entire surface.

  It should be considered that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is shown not by the above embodiments but by the scope of the claims, and is intended to include all modifications and variations within the meaning and scope equivalent to the scope of the claims.

It is a fragmentary perspective view which shows the resin layer in the piezoelectric structure as one embodiment of this invention. It is the fragmentary sectional view seen from the direction along the II-II line of FIG. It is the fragmentary sectional view seen from the direction in alignment with the II-II line of FIG. 1 about the resin layer in the piezoelectric structure as another embodiment of this invention. It is sectional drawing which shows the piezoelectric structure of a multilayer structure as one embodiment of this invention. It is a fragmentary sectional view showing typically expansion and contraction operation of a resin layer. It is sectional drawing which shows notionally the unimorph type speaker comprised using the piezoelectric structure of this invention. It is sectional drawing which shows notionally the bimorph type speaker comprised using the piezoelectric structure of this invention. It is a fragmentary sectional view which shows typically the expansion-contraction operation | movement of the piezoelectric structure which comprises a bimorph type speaker unit. It is sectional drawing which shows one embodiment of the attenuation | damping area | region in case a speaker unit is comprised from a some vibration area | region. It is sectional drawing which shows another embodiment of the attenuation | damping area | region in case a speaker unit is comprised from a some vibration area | region. It is sectional drawing which shows another embodiment of the attenuation | damping area | region when a speaker unit is comprised from a some vibration area | region. It is a top view which shows a stereo type speaker unit. It is sectional drawing seen from the direction along the XIII-XIII line | wire of FIG. It is a top view which shows a speaker unit as another embodiment of this invention. It is a fragmentary sectional view showing the concrete composition of the bimorph type speaker unit as one embodiment of this invention. FIG. 16 is a diagram showing a relationship between wiring and polarization direction in the bimorph type speaker unit shown in FIG. 15. It is a fragmentary sectional view showing the concrete composition of the bimorph type speaker unit as another embodiment of this invention. It is a figure which shows the relationship between wiring and a polarization direction in the bimorph type speaker unit shown by FIG. It is a perspective view which shows a mobile telephone as one example of application of the speaker of this invention. FIG. 5 is a plan view showing a portable game machine as another application example of the present invention.

Explanation of symbols

  1, 1a, 1b, 1c: columnar single crystal, 2: resin portion, 10, 11, 12: resin layer, 21, 22: electrode layer, 100, 110, 120, 130: piezoelectric structure, 200: transparent substrate , 300, 310: elastic member, 1000, 1100, 1200: speaker unit, 1001: groove, 1002: through hole.

Claims (9)

A resin layer having opposite main surfaces on both sides;
A transparent electrode layer disposed so as to sandwich the main surface on both sides of the resin layer,
The resin layer includes a transparent resin portion and a plurality of columnar dispersed portions exhibiting piezoelectricity dispersed in the resin portion,
The dispersed portion is oriented and distributed in the resin portion so that the major axis direction is substantially parallel to the normal direction of the resin portion, has a diameter of 400 nm or less, and is polarized in the major axis direction. A piezoelectric structure.   The piezoelectric structure according to claim 1, wherein the resin layer and the electrode layer are alternately laminated.   A speaker comprising the piezoelectric structure according to claim 1.   The speaker according to claim 3, comprising a transparent base material having a main surface, wherein the piezoelectric structure is bonded onto the main surface of the base material.   The speaker according to claim 3 or 4, comprising a plurality of the piezoelectric structures stacked.   6. The piezoelectric structure according to claim 3, wherein the piezoelectric structure has a main surface, and the plurality of piezoelectric structures are joined so that the main surfaces are continuous to form a plurality of vibration regions. The speaker according to item.   The speaker according to claim 6, wherein the plurality of vibration regions have different resonance frequencies.   The speaker according to claim 7, wherein the plurality of vibration regions have different areas.   The speaker according to any one of claims 6 to 8, wherein a damping region for attenuating vibrations of a plurality of adjacent vibration regions is provided at a boundary between the plurality of vibration regions.

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