JP2017215319A - Piezoelectric sensor and display using piezoelectric sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric sensor improving optical transparency and haze, compared with a conventional one, and a display using the piezoelectric sensor.SOLUTION: A piezoelectric sensor 10, 11 is arranged on a surface of a display 12. The piezoelectric sensor 10, 11 includes: a piezoelectric film 15 having piezoelectricity; transparent electrodes 16, 17 formed on one side and the other side of the piezoelectric film 15; and a transparent filler layer 18 formed on a side opposite to the piezoelectric film 15 with regard to the transparent electrodes 16, 17. The piezoelectric film 15 has a film-like shape with a coating layer 14 having piezoelectricity laminated on a substrate film 13. A simple substance film having piezoelectricity may be used as a piezoelectric film 15.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a piezoelectric sensor for detecting pressure and a display using the piezoelectric sensor.

  Conventionally, a touch panel is attached to the front surface of a display of an electronic device and is used for operation of the electronic device. The touch panel only detects the position coordinates, but it can also detect the pressing force by adding a pressure sensor. For example, the following patent document 1 discloses a touch panel that can also detect a pressing force.

  In the touch panel of Patent Document 1, the end of a film-like piezoelectric sensor is bonded to a display with an adhesive. There is a space between the film-like piezoelectric sensor and the display. When the film-like piezoelectric sensor is pressed, the pressed portion is bent toward the display, and the pressed portion is extended. The pressing force is detected based on the intensity of a signal generated by the shape change of the film-like piezoelectric sensor.

  However, the touch panel of Patent Document 1 may deteriorate light transmittance and haze due to the space between the film-like piezoelectric sensor and the display.

JP2014-144452A

  An object of the present invention is to provide a piezoelectric sensor with improved light transmission and haze as compared with the conventional one and a display using the piezoelectric sensor.

  The present invention is a piezoelectric sensor disposed in front of a display. The piezoelectric sensor includes a piezoelectric film in which a coating layer having piezoelectricity is laminated on a base film or a single film having piezoelectricity, and a transparent electrode disposed directly or indirectly on at least one side of the piezoelectric film, A transparent filling layer filling the space between the transparent electrode and the display.

  The refractive index of the transparent filling layer is a refractive index between the refractive index of the transparent electrode and the refractive index of the display.

  The transparent filling layer is an adhesive or a resin.

  The piezoelectric coating layer and the piezoelectric single film include a fluororesin.

  The fluororesin is a copolymer of two or more of vinylidene fluoride, trifluoroethylene, and chlorotrifluoroethylene, or a polymer of vinylidene fluoride.

  A refractive index adjusting layer is provided on at least one of the piezoelectric film between the base film and the coating layer, between the piezoelectric film and the transparent electrode, or on the single film having piezoelectricity. Further, the anchor coat layer is formed on either one of the piezoelectric film between the base film and the coating layer, or on the surface of the base film opposite to the coating layer, or on the piezoelectric single element film. Have

  The coating layer has a thickness of 0.5 to 10 μm, the refractive index adjustment layer has a thickness of 80 to 160 nm, and the transparent electrode has a thickness of 20 nm or more. The refractive index of the coating layer is 1.40 to 1.50, the refractive index of the refractive index adjusting layer is 1.50 to 1.70, and the refractive index of the transparent electrode is 1.90 to 2.10.

  A touch panel may be disposed on the opposite side of the display in the piezoelectric film.

  The display of the present invention includes the above piezoelectric sensor, and the space between the piezoelectric sensor and the display is filled with the transparent filling layer.

  The piezoelectric sensor of the present invention is provided with a transparent filling layer so as to cover the entire surface facing the display. Therefore, unlike a film-like piezoelectric sensor having an air layer between the display and a conventional display, it is difficult to reduce optical characteristics such as total light transmittance and haze. The refractive index of the transparent electrode, the transparent filling layer, and the display is gradually changed, and there is little reflection / scattering of light, and it is difficult to deteriorate optical characteristics.

  The display of the present invention includes the above-described piezoelectric sensor, and there is no air layer at the boundary between the display and the piezoelectric sensor, and a transparent filling layer is filled. Therefore, it is difficult to reduce optical characteristics such as total light transmittance and haze when the display is viewed.

It is a figure which shows typically the structure of the piezoelectric sensor of this invention. It is a figure which shows typically the other structure of the piezoelectric sensor which has arrange | positioned one transparent electrode of this invention indirectly. It is a figure which shows typically the other structure of the piezoelectric sensor which has arrange | positioned one transparent electrode of this invention indirectly. It is a figure which shows typically the other structure of the piezoelectric sensor which has arrange | positioned both the transparent electrodes of this invention indirectly. It is a figure which shows typically the other structure of the piezoelectric sensor of this invention. It is a figure which shows typically the other structure of the piezoelectric sensor of this invention. It is a figure which shows typically the other structure of the piezoelectric sensor of this invention. It is a figure which shows typically the structure of the piezoelectric sensor using the single-piece | unit film which has piezoelectricity of this invention. It is a figure which shows typically the structure provided with the refractive index adjustment layer in the piezoelectric sensor of FIG. It is a figure which shows typically the structure which performed Examples 3-9.

  The piezoelectric sensor and display of the present invention will be described with reference to the drawings.

  The piezoelectric sensors 10 and 11 of the present invention shown in FIGS. 1A and 1B are arranged on the display surface of a display 12. The piezoelectric sensors 10 and 11 include a piezoelectric film 15 having piezoelectricity, transparent electrodes 16 and 17 formed on one surface and the other surface of the piezoelectric film 15, and transparent formed on the opposite surface of the piezoelectric film 15 in one transparent electrode 17. A packed bed 18 is provided.

  The piezoelectric film 15 is a film in which a base film 13 is laminated with a coating layer 14 having piezoelectricity.

[Base film]
Examples of the base film 13 include polymer films such as polyethylene terephthalate, polyethylene naphthalate, polyolefin, polycycloolefin, polycarbonate, polyether sulfone, polyarylate, polyimide, polyamide, polystyrene, and polynorbornene. The base film 13 is preferably a polyethylene terephthalate film (PET film) excellent in transparency, heat resistance, and mechanical properties, but is not limited thereto.

  The thickness of the base film 13 is preferably 10 μm or more and 200 μm or less, but is not limited thereto. However, if the thickness of the base film 13 is less than 10 μm, handling may be difficult. Moreover, when the thickness of the base film 13 exceeds 200 μm, it may be difficult to wind up the piezoelectric film into a roll. On the other hand, if the thickness of the base film 13 exceeds 200 μm, the piezoelectric film 15 may be too thick when mounted on the touch panel.

[Coating layer with piezoelectricity]
The coating layer 14 having piezoelectricity is a thin film coated on the base film 13. The coating layer 14 having piezoelectricity is not particularly limited as long as the coated film has piezoelectricity. The coating layer 14 having piezoelectricity desirably exhibits piezoelectricity without performing poling (polarization treatment), but may exhibit piezoelectricity after poling.

  The coating layer 14 having piezoelectricity is, for example, a solution obtained by dissolving the material of the coating layer in a solvent, and coating the substrate film 13 thinly and uniformly by a known coating apparatus such as a bar coater or a gravure coater, Thereafter, it is obtained by drying.

  As shown in FIGS. 1A and 1B, the vertical direction of the piezoelectric film 15 relative to the display 12 is not limited. In FIG. 1A, the base film 13 is on the display 12, and in FIG. 1B, the piezoelectric coating layer 14 is on the display 12.

[Material of coating layer having piezoelectricity]
As the material of the coating layer 14 having piezoelectricity, for example, a material containing a fluorine resin is preferably used. Specific examples of a material containing a fluororesin include polyvinylidene fluoride which is a vinylidene fluoride component-containing polymer, a copolymer of vinylidene fluoride-trifluoroethylene, and vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene. Copolymer, copolymer of hexafluoropropylene-vinylidene fluoride, copolymer of perfluorovinyl ether-vinylidene fluoride, copolymer of tetrafluoroethylene-vinylidene fluoride, copolymer of hexafluoropropylene oxide-vinylidene fluoride It can be selected from a polymer, a copolymer of hexafluoropropylene oxide-tetrafluoroethylene-vinylidene fluoride, and a copolymer of hexafluoropropylene-tetrafluoroethylene-vinylidene fluoride. These polymers can be used alone or as a mixture. More preferred are a vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene copolymer, a vinylidene fluoride-trifluoroethylene copolymer, and a vinylidene fluoride polymer.

  When a copolymer of vinylidene fluoride-trifluoroethylene is used as the material of the coating layer 14, the molar ratio of vinylidene fluoride and trifluoroethylene is 100 as a whole, and (70 to 75): (30 to 25) is appropriate. It is. When a vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene copolymer is used as the material of the coating layer 14, the molar ratio of vinylidene fluoride, trifluoroethylene, and chlorotrifluoroethylene is 100 as a whole. 63-65) :( 27-29) :( 10-6) is suitable.

[Thickness of coating layer having piezoelectricity]
The thickness of the coating layer 14 having piezoelectricity after drying is not limited, but considering the optical characteristics described later, 0.5 μm or more and 20 μm or less, preferably 0.5 μm or more and 5 μm or less are appropriate. is there. If the thickness of the coating layer 14 having piezoelectricity after drying is less than 0.5 μm, the formed film may be incomplete. If the thickness of the coating layer 14 having piezoelectricity after drying exceeds 20 μm, the optical properties (haze and total light transmittance) may become inappropriate.

[Optical characteristics of piezoelectric film]
Since the image of the display 12 must be clearly seen, the haze value of the piezoelectric film 15 is preferably 5% or less, the total light transmittance is preferably 85% or more, more preferably 88% or more, and further 90% or more. preferable. If the haze value of the piezoelectric film 15 exceeds 5%, or if the total light transmittance is less than 85%, the image on the display 12 may not be clearly visible.

[Transparent electrode]
The transparent electrodes 16 and 17 are disposed on both surfaces of the piezoelectric film 15. When the piezoelectric sensors 10 and 11 are pressed, the piezoelectric coating layer 14 is polarized, and a change in the potential of the piezoelectric coating layer 14 is detected by one transparent electrode 16. The other transparent electrode 17 becomes a reference potential (ground potential). The transparent electrodes 16 and 17 are formed so as to cover the entire surfaces of the piezoelectric film 15.

  Examples of the transparent electrodes 16 and 17 include indium composite oxides, typically indium tin oxide (ITO) and indium zinc composite oxides. An example is doped indium oxide (In203). Indium-based composite oxides are characterized by high transmittance of 80% or more in the visible light region (380 to 780 nm) and low surface resistance per unit area (30 to 1000 Ω / □).

  The surface resistance value of the indium composite oxide is preferably 300Ω / □ (ohms per square) or less, and more preferably 150Ω / □. The transparent electrodes 16 and 17 having a low surface resistance are formed by, for example, forming an amorphous layer of indium-based composite oxide on the cured resin layer by sputtering or vacuum deposition, and then performing heat treatment at 100 to 200 ° C. It can be obtained by changing the amorphous layer into a crystalline layer.

  The transparent electrodes 16 and 17 are not limited to the above materials, and transparent conductive oxides such as tin zinc oxide, zinc oxide, and fluorine-doped tin oxide, and conductive polymers such as polyethylenedioxythiophene can be used. .

[Interlayer]
For example, in FIG. 1A, the refractive index adjusting layer (at least between the base film 13 and the coating layer 14, between the base film 13 and the transparent electrode 17, or between the coating layer 14 and the transparent electrode 16). An Index matching layer) may be provided. In the case of forming a plurality of refractive index adjustment layers, the refractive index adjustment layer is formed between the base film 13 and the coating layer 14 and on any surface of the piezoelectric film 15. The refractive index adjustment layer is a thin layer of about several nm to several tens of nm and adjusts the reflectance. In FIG. 1B, the above layers may be formed similarly.

  An anchor coat layer (anchor coat layer) may be formed between the base film 13 and the coating layer 14 on the surface of the base film 13 opposite to the coating layer 14. The anchor coat layer can improve the adhesion between the layers.

  Further, an anti-blocking layer may be provided between the base film 13 and the transparent electrodes 16 and 17. The anti-blocking layer has an effect of preventing the stacked films from being pressed (blocked).

  As for the interlayer, not one of the above-described layers is formed, and a plurality of types of layers may be formed in one piezoelectric sensor 10, 11.

[Transparent packing layer]
The transparent filling layer 18 is formed on the entire opposite surface of the piezoelectric film 15 in one transparent electrode 17. A space between the transparent electrode 17 and the display 12 is filled with a transparent filling layer 18.

  The transparent filling layer 18 uses an adhesive or resin made of an optical transparent adhesive material or an optical transparent adhesive material. The transparent filling layer 18 in the form of a sheet may be bonded to the surface of the transparent electrode 17 to form the transparent filling layer 18, or the liquid transparent filling layer 18 is applied to the surface of the transparent electrode 17 and irradiated with ultraviolet rays. Then, the transparent filling layer 18 may be formed by curing. The transparent filling layer 18 is formed when the piezoelectric sensors 10 and 11 are attached to the display 12. It is also possible to form the transparent filling layer 18 on the front surface of the display 12 instead of the transparent electrode 17.

  The refractive index of the transparent filling layer 18 is a refractive index between the refractive index of the transparent electrode 17 and the refractive index of the display 12. The refractive index is gradually changed to suppress light scattering and the like. When indium tin oxide is used for the transparent electrode 17, an adhesive or resin is used for the transparent filling layer 18, and a PET film is used for the outermost layer of the functional film on the front surface of the display 12, the transparent electrode 17, the transparent filling layer 18, and the outermost layer of the display 12 Each of the refractive indexes can be about 1.7, 1.5, and 1.3.

[display]
As the display 12, a flat display such as a liquid crystal display or an organic EL display can be used. Piezoelectric sensors 10 and 11 are arranged on the front surface of the display 12. The piezoelectric sensors 10 and 11 are bonded to the display 12 by the transparent filling layer 18 of the piezoelectric sensors 10 and 11. There is no air layer between the piezoelectric sensors 10, 11 and the display 12, and the transparent filling layer 18 covers the entire front surface of the display 12.

[Touch panel]
A touch panel may be disposed on the transparent electrode 16 of the piezoelectric sensors 10 and 11. The piezoelectric sensors 10 and 11 and the touch panel are stacked on the display 12 in this order. Between the piezoelectric sensors 10 and 11 and the touch panel, the same material as the transparent filling layer 18 may be filled and bonded.

  The touch panel includes an arbitrary touch panel such as a capacitance type or a resistance film type. The position pressed on the touch panel is detected. The transparent electrode 16 on the upper side of the piezoelectric sensors 10 and 11 may function as a touch panel electrode. Since the piezoelectric sensors 10 and 11 do not bend as in the prior art, a capacitive touch panel can be used without being bent. The detection accuracy of the pressed position can be increased, and the life of the touch panel can be extended.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to said embodiment. For example, the transparent electrodes 16 and 17 may be disposed indirectly with respect to the piezoelectric film 15. Only one transparent electrode 16 may be directly formed on the piezoelectric film 15 as in the piezoelectric sensors 20 and 21 in FIGS. A laminate 24 in which a transparent electrode 17 is laminated on a base film 23 is formed, transparent filling layers 18 and 25 are provided on both sides of the laminate 24, one transparent filling layer 25 is a piezoelectric film 15, and the other transparent filling is provided. Layer 18 is applied to display 12. The transparent filling layers 18 and 25 cover the entire surface of the laminate 24 and the other surface. In addition, the base film 23 and the transparent filling layer 25 can use the same thing as the base film 13 and the transparent filling layer 18 of FIG.

  Only the other transparent electrode 17 may be directly formed on the piezoelectric film 15 as in the piezoelectric sensors 30 and 31 of FIGS. A laminated body 33 in which one transparent electrode 16 is laminated on the base film 32 is formed, and the laminated body 33 and the piezoelectric film 15 are bonded by the transparent filling layer 34. The base film 32 and the transparent filling layer 34 can be the same as the base film 13 and the transparent filling layer 18 of FIG.

  A combination of the piezoelectric sensors 20, 21, 30, and 31 of FIGS. 2 and 3 may be used as in the piezoelectric sensors 40 and 41 of FIGS. 4 (a) and 4 (b). Two laminated bodies 24 and 33 are bonded to the piezoelectric sensor 15 with transparent filling layers 25 and 36, and two transparent electrodes 16 and 17 are indirectly arranged.

  Further, in the piezoelectric sensor 50 of FIG. 5, the laminate 24 is disposed on the transparent electrode 16 directly formed on the piezoelectric film 15 via the transparent filling layer 25. The transparent electrode 17 of the laminated body 24 becomes a reference potential.

  In FIG. 5, the piezoelectric film 15 has the piezoelectric coating layer 14 disposed on the display 12 side, but the base film 13 may be disposed on the display 12 side. Moreover, although the laminated body 24 has arrange | positioned the base film 23 on the display 12 side, you may arrange | position the transparent electrode 17 on the display 12 side.

  As in the piezoelectric sensor 60 of FIG. 6, the transparent electrode 16 is not directly formed on the piezoelectric film 15 in the piezoelectric sensor 50 of FIG. 5, and the laminate 33 is prepared and adhered to the piezoelectric film 15 by the transparent filling layer 34. You may do it. As in FIG. 5, the laminate 33 has the base film 32 disposed on the display 12 side, but the transparent electrode 16 side may be disposed on the display 12 side.

  Instead of forming the two transparent electrodes 16 and 17 on separate substrate sheets as in the piezoelectric sensor 70 of FIG. 7, a laminate 71 formed on one substrate film 72 may be used. The laminated body 71 has transparent electrodes 16 and 17 formed on one surface and the other surface of the base film 72. One of the laminates 71 is adhered to the piezoelectric film 15 by the transparent filling layer 34, and the other of the laminates 71 is adhered to the display 12 by the transparent filling layer 18. The base film 71 can be the same as the base film 13 of the piezoelectric film 15.

  Furthermore, it is not limited to using said piezoelectric film 15. For example, a single film 81 having piezoelectricity may be used as the piezoelectric film 15 in FIG. 1 like the piezoelectric sensor 80 in FIG. The piezoelectric sensor 80 has the same configuration as that of the piezoelectric sensor 10 of FIG. 1 except for a single film 81 having piezoelectricity. Hereinafter, the single film 81 having piezoelectricity will be described, but the other configuration is described in the touch sensor 10 and thus omitted.

[Single film with piezoelectric properties]
The single film 81 having piezoelectricity is not particularly limited as long as it has piezoelectricity. The single film 81 having piezoelectricity desirably exhibits piezoelectricity without performing poling (polarization treatment), but may exhibit piezoelectricity after poling.

  There are two known types of poling, a non-contact method using corona discharge treatment polarization and a contact method in which a film is sandwiched between two metal plates and polarized by applying a voltage.

[Material of single film having piezoelectricity]
As the material of the single film 81 having piezoelectricity, for example, a material containing a fluorine resin is preferably used. Specific examples of a material containing a fluororesin include polyvinylidene fluoride which is a vinylidene fluoride component-containing polymer, a copolymer of vinylidene fluoride-trifluoroethylene, and vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene. Copolymer, copolymer of hexafluoropropylene-vinylidene fluoride, copolymer of perfluorovinyl ether-vinylidene fluoride, copolymer of tetrafluoroethylene-vinylidene fluoride, copolymer of hexafluoropropylene oxide-vinylidene fluoride It can be selected from a polymer, a copolymer of hexafluoropropylene oxide-tetrafluoroethylene-vinylidene fluoride, and a copolymer of hexafluoropropylene-tetrafluoroethylene-vinylidene fluoride. These polymers can be used alone or as a mixture. More preferred are a vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene copolymer, a vinylidene fluoride-trifluoroethylene copolymer, and a vinylidene fluoride polymer.

  When a vinylidene fluoride-trifluoroethylene copolymer is used as the material of the single film 81 having piezoelectricity, the molar ratio of vinylidene fluoride and trifluoroethylene is 100 as a whole, (70 to 75): (30 to 25) is appropriate. When a vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene copolymer is used as the material of the coating layer 14, the molar ratio of vinylidene fluoride, trifluoroethylene, and chlorotrifluoroethylene is 100 as a whole. 63-65) :( 27-29) :( 10-6) is suitable.

[Thickness of single film having piezoelectricity]
Although the thickness of the single film 81 having piezoelectricity is not limited, in consideration of the optical characteristics described later, 0.5 μm or more and 20 μm or less, preferably 0.5 μm or more and 5 μm or less are appropriate. If the thickness of the single film 81 having piezoelectricity is less than 0.5 μm, the formed film may be incomplete. If the thickness of the single film 81 having piezoelectricity exceeds 20 μm, the optical characteristics (haze and total light transmittance) may become inappropriate.

  At least one of an anchor coat layer, an index matching layer (optical matching layer), and an anti-blocking layer may be formed on at least one surface of the single film 81 having piezoelectricity. . The refractive index adjustment layer is a thin layer of about several nm to several tens of nm and adjusts the reflectance. The anchor coat layer can improve the adhesion between the layers. Furthermore, the anti-blocking layer has an effect of preventing the stacked films from being pressed (blocked).

  Also, in the piezoelectric sensors 20, 21, 30, 31, 40, 41, 50, 60, 70 of FIGS. 2 to 7, the piezoelectric film 15 may be replaced with a single film 81 having piezoelectricity.

  When the piezoelectric sensor 80 is pressed, the single film 81 having piezoelectricity is polarized, and the change in potential at that time is detected by the transparent electrode 16, whereby the pressing force can be detected.

  Moreover, you may apply said refractive index adjustment layer etc. to the piezoelectric sensors 10, 11, 20, 21, 30, 31, 40, 41, 50, 60, 70 of FIGS. For example, although the piezoelectric film 15 and the transparent electrode 16 are laminated in FIG. 1, a refractive index adjusting layer 92 is laminated between the piezoelectric film 15 and the transparent electrode 16 like the piezoelectric sensors 90 and 91 in FIG.

  As an example, the thickness of the coating layer 14 having piezoelectricity is 0.5 to 10 μm, the thickness of the refractive index adjusting layer 92 is 80 to 160 nm, and the thickness of the transparent electrode 16 is 20 nm or more. Further, the refractive index of the coating layer 14 having piezoelectricity is 1.40 to 1.50, the refractive index of the refractive index adjusting layer 92 is 1.50 to 1.70, and the refractive index of the transparent electrode 16 is 1.90 to 2. .10 is an example. Moreover, the thickness of the base film 13 is set to 2 to 100 μm, and the refractive index is set to 1.50 to 1.70. By using the above thickness and refractive index, the difference in reflectance between the transparent electrode 16 and the refractive index adjustment layer 92 becomes 2.0% or less, and the appearance of the piezoelectric sensors 90 and 91 is improved.

[Example 1]
In Example 1, a glass substrate was used in place of the display 12 in FIG. 1A in order to measure the optical characteristics of the piezoelectric sensor 10, and the total light transmittance and haze were confirmed. The piezoelectric film 15 was produced by coating a polyethylene terephthalate base film with a copolymer of vinylidene fluoride, trifluoroethylene, and chlorotrifluoroethylene. The polyethylene terephthalate base film was LR-50JBN manufactured by Mitsubishi Plastics, Inc., and the thickness was 50 μm. The copolymer of vinylidene fluoride, trifluoroethylene, and chlorotrifluoroethylene was Piezotech RT ^™ TS manufactured by Arkema Co., Ltd., and a solution was prepared in MIBK (methyl isobutyl ketone) by ultrasonic waves. Next, a solution of a copolymer of vinylidene fluoride, trifluoroethylene, and chlorotrifluoroethylene was coated on a polyethylene terephthalate base film by a bar coater. Next, the polyethylene terephthalate base film and the undried coating layer were dried at 110 ° C. for 5 minutes to prepare a coating layer. The thickness of the coating layer after drying was 1 μm.

  An indium tin oxide film was formed on both surfaces of the piezoelectric film 15 by sputtering, and a sheet-like transparent filling layer was further attached. The thickness of the indium tin oxide layer was 23 nm. The sheet-shaped transparent packed bed is No. manufactured by Nitto Denko Corporation. 25 and the thickness was 25 μm.

  The glass substrate was MICRO SLIDE GLASS manufactured by Matsunami Co., Ltd., and the thickness was 1.2 to 1.5 mm. The glass substrate is a substitute for a display and has a refractive index of 1.5.

  The total light transmittance including the piezoelectric sensor 10 and the display 12 was 83.9%, and the haze was 1.8%.

[Example 2]
In Example 2, a glass substrate was used in place of the display 12 in FIG. 2A in order to measure the optical characteristics of the piezoelectric sensor 21, and the total light transmittance and haze were confirmed. The materials used and the method for producing the piezoelectric film 15 are the same as in the first embodiment. The total light transmittance was 85.0%, and the haze was 1.4%.

  In addition, Example 2 has better total light transmittance and haze than Example 1. In FIG. 1A, the transparent electrode 17 is formed directly on the base film 13, but in FIG. 2A, there is a transparent filling layer 25 between the base film 13 and the transparent electrode 22. The surface of the transparent electrode 22 (indium tin oxide here) has fine irregularities, and it is considered that light scattering can be prevented by covering with the transparent filling layer 25 as shown in FIG.

[Comparative Example 1]
In Comparative Example 1, the transparent filling layer in Example 1 was changed to an air layer, and the total light transmittance and haze were confirmed. The transparent filling layer was not attached to the entire surface of indium tin oxide, but was attached to the end of indium tin oxide to form an air layer in the center. The total light transmittance was 75.8%, and the haze was 2.5%, both of which were worse than Example 1.

[Comparative Example 2]
In Comparative Example 2, the transparent filling layer facing the display in Example 2 was changed to an air layer, and the total light transmittance and haze were confirmed in the portion where the air layer was formed. The total light transmittance was 79.7% and the haze was 1.8%, both of which were worse than Example 2.

  In addition, about the thickness in said Example and a comparative example, when less than 1.0 micrometers, such as the coating layer 14 of the piezoelectric film 15, it observed and measured the cross section using the transmission electron microscope (Hitachi Ltd. make, H-7670). . The thickness of 1.0 μm or more such as the base film 13 was measured using a film thickness meter (Peacock, Digital Dial Gauge DG-205). Further, total light transmittance and haze were measured using a Direct reading haze computer (HGM-ZDP manufactured by Suga Test Instruments).

  The examples and comparative examples are summarized in Table 1. When Example 1 and Comparative Example 1 are compared, and Example 2 and Comparative Example 2 are compared, it can be seen that all Examples have better total light transmittance and haze than the Comparative Example, and that the present application has better optical characteristics than the conventional example. In addition, the total light transmittance and haze of the piezoelectric film used alone in the examples and comparative examples were measured in the same manner as in the examples. The total light transmittance was 91.6%, the haze was 0.9%, and the total light transmittance was 85% or more and the haze was 5% or less.

  As described above, it can be understood that the optical characteristics are improved by using the transparent filling layer instead of the conventional air layer. When the piezoelectric sensor is disposed on the front surface of the display, the piezoelectric sensor of the present application hardly reduces the visibility of the display.

[Examples 3 to 8]
Further, as shown in FIG. 10, a coating layer 14 having a piezoelectric property, a refractive index adjusting layer 92, and a transparent electrode 16 were formed on a base film 13 having a thickness of 23 μm, and the thickness and refractive index were measured. The results are shown in Table 2. The “first layer” is the piezoelectric coating layer 14, the “second layer” is the refractive index adjustment layer 92, and the “third layer” is the transparent electrode 16. Except for the formation of the refractive index adjustment layer 92, this embodiment is the same as the above embodiment.

  As shown in Table 2 below, the refractive index adjustment layer 92 may have a refractive index of 1.54, 1.62, 1.7. Since the manufacturing method differs depending on the refractive index, each refractive index will be described. When the refractive index is 1.54, a thermosetting resin having a weight ratio of 2: 2: 1 of melamine resin: alkyd resin: organosilane condensate (refractive index of light) is formed on one surface of the coating layer 14 having piezoelectricity. n = 1.54), a refractive index adjusting layer 92 having a thickness of 120 nm was formed.

When the refractive index is 1.62, an optical adjustment composition containing 47 parts by mass of ultraviolet curable resin, 57 parts by mass of zirconia oxide particles (median diameter 40 nm) and PGME on one surface of the coating layer 14 having piezoelectricity (Manufactured by JSR, “OPSTAR Z7412”, solid content: 12% by mass) was applied using a gravure coater, and immediately heated and dried at 60 ° C. for 1 minute in a windless state (less than 0.1 m / s). Then, the curing process was performed by irradiating ultraviolet rays with an integrated light amount of 250 mJ / cm ² with a high-pressure mercury lamp. By this method, a refractive index adjusting layer 92 having a thickness of 90, 120, or 150 nm and a refractive index of 1.62 was formed on the coating layer 14 having piezoelectricity.

When the refractive index is 1.7, a thermosetting resin composed of a melamine resin, an alkyd resin, and an organic silane condensate (by weight ratio, melamine resin: alkyd resin: organosilane condensate = 2: 2: 1) and TiO ₂ A resin composition in which fine particles (refractive index = 2.35) were mixed was prepared. At this time, the mixing amount of the TiO ₂ fine particles was adjusted so that the refractive index of the resin composition was 1.70. And the said resin composition was apply | coated on the coating layer 14 which has piezoelectricity, this was hardened, and the 150-nm-thick refractive index adjustment layer 92 (refractive index 1.70) was formed.

  A hard coat layer 94 having an anti-blocking function is formed on the opposite surface of the base film 13 to the coating layer 14.

  In each example, as described above, the thickness of the coating layer 14 having piezoelectricity is 0.5 to 10 μm, the thickness of the refractive index adjusting layer 92 is 80 to 160 nm, and the thickness of the transparent electrode 16 is 20 nm or more. Yes. The refractive index of the coating layer 14 having piezoelectricity is 1.40 to 1.50, the refractive index of the refractive index adjusting layer 92 is 1.50 to 1.70, and the refractive index of the transparent electrode 16 is 1.90 to 2. .10. The difference in reflectance between the transparent electrode 16 and the refractive index adjustment layer 92 was 2% or less, and the appearance was good.

  In addition, the transparent electrode 16 is etched as needed to become a desired electrode or the like. When obtaining the refractive index, the refractive index of the refractive index adjusting layer 92 was the portion where the transparent electrode 16 was removed by etching. Therefore, the reflectance difference was calculated | required by calculating | requiring the reflectance of air and the transparent electrode 16, air, and the refractive index adjustment layer 92 from each refractive index.

[Comparative Examples 3 to 4]
As a comparative example for Examples 3 to 8, the case where the refractive index adjustment layer 92 is not provided (Comparative Example 3) and the case where the refractive index of the refractive index adjustment layer 92 is smaller than 1.5 (Comparative Example 4) were performed. When the refractive index adjusting layer 92 is not provided, the reflectance difference is a difference between the transparent electrode 16 and the coating layer 14 having piezoelectricity. The difference in reflectance was greater than 2% and the appearance was poor.

In the case where the refractive index is 1.46 (Comparative Example 4), the refractive index adjustment layer 92 is obtained by diluting silica sol (Colcoat P, Colcoat P) with ethanol so that the solid content concentration is 2%. It is applied on one of the coating layers 14 having piezoelectricity by a silica coating method, and then dried and cured at 150 ° C. for 2 minutes to form a layer having a thickness of 120 nm (SiO ₂ film, refractive index of light 1.. 46) to form a refractive index adjusting layer 92. In the comparative example, the manufacturing method of the other configuration is the same as that of the example.

  As described above, by providing the transparent electrode 16 on the coating layer 14 having piezoelectricity, the transparent electrode 16 may be colored yellow or brown to impair the appearance. By providing the refractive index adjustment layer 92 as in the present invention, the thickness and refractive index of the transparent electrode 16, the refractive index adjustment layer 92, and the coating layer 14 having piezoelectricity are adjusted to be in the above-described range. As shown in Table 2, it was found that the difference in reflectance can be reduced and the appearance is not impaired. It has been found that even if a configuration in which the refractive index adjustment layer 92 and the transparent electrode 16 are laminated on the piezoelectric film 15 is disposed on the front surface of the display, the appearance of the display is hardly impaired.

  In addition, the present invention can be carried out in a mode in which various improvements, modifications, and changes are added based on the knowledge of those skilled in the art without departing from the spirit of the present invention.

  The piezoelectric sensor of the present invention can be used integrally with a touch panel disposed on the front surface of the display.

10, 11, 20, 21, 30, 31, 40, 41, 50, 60, 70, 80, 90, 91: Piezoelectric sensor 12: Display 13, 23, 32, 72: Base film 14: Having piezoelectricity Coating layer 15: Piezoelectric films 16, 17, 22: Transparent electrodes 18, 25, 34: Transparent filling layers 24, 33: Laminate 81: Single film 92 having piezoelectricity: Refractive index adjusting layer 94: Anti-blocking function Hard coat layer

Claims (13)

A piezoelectric sensor disposed in front of the display,
A piezoelectric film having piezoelectricity;
A transparent electrode disposed directly or indirectly on at least one side of the piezoelectric film;
A transparent filling layer filling between the transparent electrode and the display;
Piezoelectric sensor with The piezoelectric sensor according to claim 1, wherein a refractive index of the transparent filling layer is a refractive index between a refractive index of the transparent electrode and a refractive index of a display. The piezoelectric sensor according to claim 1, wherein the transparent filling layer is an adhesive or a resin. 4. The piezoelectric film according to claim 1, wherein the piezoelectric film has a piezoelectric coating layer accumulated on a base film, and the piezoelectric coating layer contains a fluororesin. Piezoelectric sensor. The piezoelectric sensor according to claim 1, wherein the piezoelectric film having piezoelectricity is a single film containing a fluorine-based resin. 6. The piezoelectric sensor according to claim 4, wherein the fluororesin is a copolymer of two or more of vinylidene fluoride, trifluoroethylene, and chlorotrifluoroethylene, or a polymer of vinylidene fluoride. The piezoelectric sensor according to claim 1, further comprising a refractive index adjusting layer between at least one of the piezoelectric film between the base film and the coating layer or between the piezoelectric film and the transparent electrode. The piezoelectric sensor according to claim 7, wherein the coating layer has a thickness of 0.5 to 10 μm, the refractive index adjustment layer has a thickness of 80 to 160 nm, and the transparent electrode has a thickness of 20 nm or more. The refractive index of the coating layer is 1.40 to 1.50, the refractive index of the refractive index adjusting layer is 1.50 to 1.70, and the refractive index of the transparent electrode is 1.90 to 2.10. 8 piezoelectric sensors. 5. The piezoelectric sensor according to claim 4, wherein the piezoelectric film has an anchor coat layer on either the base film and the coating layer of the piezoelectric film or on the surface of the base film opposite to the coating layer. 6. The piezoelectric sensor according to claim 5, further comprising an anchor coat layer on one surface of the single film having piezoelectricity. The piezoelectric sensor according to claim 1, wherein a touch panel is disposed on the opposite side of the display in the piezoelectric film. A display comprising the piezoelectric sensor according to claim 1, wherein a space between the piezoelectric sensor and the display is filled with the transparent filling layer.

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