JP7050426B2 - Piezoelectric sensor and display using the piezoelectric sensor - Google Patents

Description

The present invention relates to a piezoelectric sensor that detects pressing and a display using the piezoelectric sensor.

Conventionally, a touch panel is attached to the front of a display of an electronic device and is used for operating the electronic device. The touch panel only detects the position coordinates, but it can also detect the pressing force by adding a pressure-sensitive sensor. For example, Patent Document 1 below discloses a touch panel capable of detecting a pressing force.

In the touch panel of Patent Document 1, the end portion of the film-shaped piezoelectric sensor is adhered to the display with an adhesive. There is a space between the film-shaped piezoelectric sensor and the display. When the film-shaped piezoelectric sensor is pressed, the pressed portion bends toward the display, and the pressed portion extends. The pressing force is detected by the strength of the signal generated by the shape change of this film-shaped piezoelectric sensor.

However, in the touch panel of Patent Document 1, the light transmission and haze may be deteriorated due to the space between the film-shaped piezoelectric sensor and the display.

JP-A-2014-134452

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

The present invention is a piezoelectric sensor located on the front surface 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 piece film having piezoelectricity, and a transparent electrode directly or indirectly arranged on at least one surface side of the piezoelectric film. A transparent packing layer that fills the space between the transparent electrode and the display is provided.

The index of refraction of the transparent packed bed is the index of refraction between the index of refraction of the transparent electrode and the index of refraction of the display.

The transparent packed bed is an adhesive or a resin.

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

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

The refractive index adjusting layer is provided between the base film and the coating layer of the piezoelectric film, between at least one between the piezoelectric film and the transparent electrode, or one of the single films having piezoelectricity. Further, an anchor coat layer is provided between the base film and the coating layer of the piezoelectric film, on either one of the surfaces of the base film on the opposite side of the coating layer, or on either of the single films having piezoelectricity. Has.

The thickness of the coating layer is 0.5 to 10 μm, the thickness of the refractive index adjusting layer is 80 to 160 nm, and the thickness of the transparent electrode is 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 arranged on the opposite side of the display in the piezoelectric film.

The display of the present invention includes the piezoelectric sensor, and the space between the piezoelectric sensor and the display is filled with the transparent packed bed.

The piezoelectric sensor of the present invention is provided with a transparent packed layer so as to cover the entire surface facing the display. Therefore, unlike the conventional film-shaped piezoelectric sensor having an air layer between the display and the display, it is difficult to reduce optical characteristics such as total light transmittance and haze. The refractive index of the transparent electrode, the transparent packed bed, and the display gradually changes, the reflection / scattering of light is small, and the optical characteristics are not easily deteriorated.

The display of the present invention includes the above-mentioned 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 visually recognized.

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 in which one transparent electrode of this invention is indirectly arranged. It is a figure which shows typically the other structure of the piezoelectric sensor in which one transparent electrode of this invention is indirectly arranged. It is a figure which shows typically the other structure of the piezoelectric sensor in which both transparent electrodes of this invention are indirectly arranged. 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 which used the single film which has the piezoelectricity of this invention. It is a figure which shows typically the structure which provided the refractive index adjustment layer in the piezoelectric sensor of FIG. It is a figure which shows typically the structure which carried out Example 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 the display 12. The piezoelectric sensors 10 and 11 are a piezoelectric film 15, 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 of the transparent electrodes 17. A packed layer 18 is provided.

The piezoelectric film 15 is in the form of a film in which a coating layer 14 having piezoelectricity is laminated on a base film 13.

[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) having excellent 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. Further, if the thickness of the base film 13 exceeds 200 μm, it may be difficult to wind the piezoelectric film into a roll. Further, if the thickness of the base film 13 exceeds 200 μm, the thickness may become too thick when the piezoelectric film 15 is mounted on the touch panel.

[Piezoelectric coating layer]
The piezoelectric coating layer 14 is a thin film coated on the base film 13. The coating layer 14 having piezoelectricity is not particularly limited as long as the film after coating has piezoelectricity. The coating layer 14 having piezoelectricity is preferably one that exhibits piezoelectricity without polling (polarization treatment), but may be one that exhibits piezoelectricity after polling.

The piezoelectric coating layer 14 is formed by, for example, dissolving the material of the coating layer in a solvent to form a solution, and coating the substrate film 13 thinly and uniformly with a known coating device such as a bar coater or a gravure coater. It is then dried and obtained.

As shown in FIGS. 1A and 1B, the vertical direction of the piezoelectric film 15 with respect 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.

[Piezoelectric coating layer material]
As the material of the coating layer 14 having piezoelectricity, for example, a material containing a fluororesin is preferably used. Specific examples of the material containing a fluororesin include polyvinylidene fluoride, which is a polymer containing a vinylidene fluoride component, a copolymer of vinylidene fluoride-trifluoroethylene, and vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene. Copolymer, hexafluoropropylene-vinylidene fluoride copolymer, perfluorovinyl ether-vinylidene fluoride copolymer, tetrafluoroethylene-vinylidene fluoride copolymer, hexafluoropropylene oxide-vinylidene fluoride co-polymer The polymer can be selected from a polymer of hexafluoropropylene oxide-tetrafluoroethylene-vinylidenefloride, and a copolymer of hexafluoropropylene-tetrafluoroethylene-vinylidenefloride. And these polymers can be used alone or as a mixture. More preferably, it is a copolymer of vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene, a copolymer of vinylidene fluoride-trifluoroethylene, or a polymer of vinylidene fluoride.

When a copolymer of vinylidene fluoride-trifluoroethylene is used as the material of the coating layer 14, the molar ratio of vinylidene fluoride to trifluoroethylene is 100 as a whole, and (70 to 75) :( 30 to 25) is appropriate. Is. When a copolymer of vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene 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 appropriate.

[Thickness of the coating layer with piezoelectricity]
The thickness of the piezoelectric coating layer 14 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. be. If the thickness of the piezoelectric coating layer 14 after drying is less than 0.5 μm, the formed film may be incomplete. If the thickness of the piezoelectric coating layer 14 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 visible, 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 arranged on both sides of the piezoelectric film 15. When the piezoelectric sensors 10 and 11 are pressed, the piezoelectric coating layer 14 is polarized, and one of the transparent electrodes 16 detects a change in the potential of the piezoelectric coating layer 14. The other transparent electrode 17 has a reference potential (earth potential). The transparent electrodes 16 and 17 are formed so as to cover the entire surface of the piezoelectric film 15.

Examples of the transparent electrodes 16 and 17 include indium-based composite oxides, typically indium tin oxide (ITO: Indium Tin Oxide), and indium zinc composite oxides, but tetravalent metal ions or divalent metal ions are used. Indium oxide (In203) doped can be mentioned. The indium-based composite oxide has a feature that the transmittance is as high as 80% or more in the visible light region (380 to 780 nm) and the surface resistance per unit area is low (30 to 1000 Ω / □).

The surface resistance value of the indium-based composite oxide is preferably 300 Ω / □ (ohms per square) or less, and more preferably 150 Ω / □. The transparent electrodes 16 and 17 having low surface resistance are subjected to heat treatment at 100 to 200 ° C. after forming an amorphous layer of an indium-based composite oxide on the cured resin layer by, for example, a sputtering method or a vacuum vapor deposition method. , 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 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 (between the base film 13 and the coating layer 14, between the base film 13 and the transparent electrode 17, or at least one between the coating layer 14 and the transparent electrode 16 ( Index matching layer) may be provided. When a plurality of refractive index adjusting layers are formed, the refractive index adjusting 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 adjusting layer is a thin layer having a degree of several nm to several tens of nm, and adjusts the reflectance. The above layer may be formed in the same manner in FIG. 1 (b).

An anchor coat layer may be formed between the base film 13 and the coating layer 14 on the opposite surface of the coating layer 14 in the base film 13. The anchor coat layer can enhance the adhesion between 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 the effect of preventing the stacked films from being crimped (blocking).

As for the layers, instead of forming any of the above-mentioned layers, a plurality of types of layers may be formed on one piezoelectric sensor 10 or 11.

[Transparent packed bed]
The transparent packed bed 18 is formed on the entire opposite surface of the piezoelectric film 15 in one of the transparent electrodes 17. A transparent packed bed 18 is filled and filled between the transparent electrode 17 and the display 12.

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

The refractive index of the transparent packing layer 18 is the 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 filler layer 18, and a PET film is used for the outermost surface layer of the functional film on the front surface of the display 12, the transparent electrode 17, the transparent filler layer 18, and the outermost surface layer of the display 12 are used. The refractive index of each of the above can be set to about 1.7, 1.5, and 1.3.

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

[Touch panel]
A touch panel may be arranged on the transparent electrodes 16 of the piezoelectric sensors 10 and 11. Piezoelectric sensors 10, 11 and a touch panel are laminated in this order on the display 12. The same material as the transparent packed layer 18 may be filled and adhered between the piezoelectric sensors 10 and 11 and the touch panel.

The touch panel includes any touch panel such as a capacitance type or a resistance film type. Detects the pressed position on the touch panel. The transparent electrode 16 on the upper side of the piezoelectric sensors 10 and 11 may function as an electrode of the touch panel. Since the piezoelectric sensors 10 and 11 do not bend as in the conventional case, any capacitive touch panel can be used without bending. The detection accuracy of the pressed position can be improved, and the life of the touch panel can be extended.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, the transparent electrodes 16 and 17 may be indirectly arranged with respect to the piezoelectric film 15. As in the piezoelectric sensors 20 and 21 of FIGS. 2A and 2B, only one of the transparent electrodes 16 may be formed directly on the piezoelectric film 15. A laminated body 24 in which a transparent electrode 17 is laminated on a base film 23 is formed, transparent packed layers 18 and 25 are provided on both sides of the laminated body 24, and one transparent packed layer 25 is a piezoelectric film 15 and the other is transparently filled. The layer 18 is attached to the display 12. The transparent packed beds 18 and 25 cover one side and the other side of the laminated body 24. As the base film 23 and the transparent packed layer 25, the same base film 13 and the transparent packed layer 18 in FIG. 1 can be used.

As in the piezoelectric sensors 30 and 31 of FIGS. 3A and 3B, only the other transparent electrode 17 may be directly formed on the piezoelectric film 15. A laminated body 33 in which one of the transparent electrodes 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 packed layer 34. As the base film 32 and the transparent packed layer 34, the same base film 13 and the transparent packed layer 18 in FIG. 1 can be used.

Like the piezoelectric sensors 40 and 41 in FIGS. 4A and 4B, the piezoelectric sensors 20, 21, 30 and 31 in FIGS. 2 and 3 may be combined. The two laminated bodies 24 and 33 are adhered to the piezoelectric sensor 15 by the transparent packed layers 25 and 36, and the two transparent electrodes 16 and 17 are indirectly arranged.

Further, in the piezoelectric sensor 50 of FIG. 5, the laminated body 24 is arranged on the transparent electrode 16 directly formed on the piezoelectric film 15 via the transparent packed bed 25. The transparent electrode 17 of the laminated body 24 serves as a reference potential.

In FIG. 5, the piezoelectric film 15 has the piezoelectric coating layer 14 arranged on the display 12 side, but the base film 13 may be arranged on the display 12 side. Further, although the base film 23 is arranged on the display 12 side in the laminated body 24, the transparent electrode 17 may be arranged on the display 12 side.

Like the piezoelectric sensor 60 of FIG. 6, in the piezoelectric sensor 50 of FIG. 5, the transparent electrode 16 is not directly formed on the piezoelectric film 15, but the laminate 33 is prepared and adhered to the piezoelectric film 15 by the transparent filler layer 34. You may. Similar to FIG. 5, in the laminated body 33, the base film 32 is arranged on the display 12 side, but the transparent electrode 16 side may be arranged on the display 12 side.

Unlike the piezoelectric sensor 70 of FIG. 7, the two transparent electrodes 16 and 17 may not be formed on separate base material sheets, but the laminated body 71 formed on one base material film 72 may be used. The laminate 71 forms transparent electrodes 16 and 17 on one surface and the other surface of the base film 72. One of the laminate 71 is adhered to the piezoelectric film 15 by the transparent filler layer 34, and the other of the laminate 71 is adhered to the display 12 by the transparent filler layer 18. As the base film 71, the same base film 13 as the piezoelectric film 15 can be used.

Further, the present invention is not limited to the use of the above-mentioned piezoelectric film 15. For example, as in the piezoelectric sensor 80 of FIG. 8, a single film 81 having piezoelectricity may be used as the piezoelectric film 15 of FIG. The piezoelectric sensor 80 has the same configuration as the piezoelectric sensor 10 of FIG. 1 except for the single film 81 having piezoelectricity. Hereinafter, the single film 81 having piezoelectricity will be described, but other configurations will be omitted because they are described by the touch sensor 10.

[Piezoelectric single film]
The single film 81 having piezoelectricity is not particularly limited as long as it has piezoelectricity. The single film 81 having piezoelectricity is preferably one that exhibits piezoelectricity without polling (polarization treatment), but may be one that exhibits piezoelectricity after polling.

Two types of polling are known: a non-contact type by corona discharge processing polarization and a contact type in which a film is sandwiched between two metal plates and a voltage is applied to polarize the polling.

[Piezoelectric single film material]
As the material of the single film 81 having piezoelectricity, for example, a material containing a fluororesin is preferably used. Specific examples of the material containing a fluororesin include polyvinylidene fluoride, which is a polymer containing a vinylidene fluoride component, a copolymer of vinylidene fluoride-trifluoroethylene, and vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene. Copolymer, hexafluoropropylene-vinylidene fluoride copolymer, perfluorovinyl ether-vinylidene fluoride copolymer, tetrafluoroethylene-vinylidene fluoride copolymer, hexafluoropropylene oxide-vinylidene fluoride co-polymer The polymer can be selected from a polymer of hexafluoropropylene oxide-tetrafluoroethylene-vinylidenefloride, and a copolymer of hexafluoropropylene-tetrafluoroethylene-vinylidenefloride. And these polymers can be used alone or as a mixture. More preferably, it is a copolymer of vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene, a copolymer of vinylidene fluoride-trifluoroethylene, or a polymer of vinylidene fluoride.

When a copolymer of vinylidene fluoride-trifluoroethylene is used as a material for the single film 81 having piezoelectricity, the molar ratio of vinylidene fluoride to trifluoroethylene is 100 as a whole, and (70 to 75) :( 30 to 30 to 25) is appropriate. When a copolymer of vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene 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 appropriate.

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

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

Further, in the piezoelectric sensors 20, 21, 30, 31, 40, 41, 50, 60, and 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 pressing force can be detected by detecting the change in potential at that time with the transparent electrode 16.

Further, the above-mentioned refractive index adjusting layer and the like may be applied to the piezoelectric sensors 10, 11, 20, 21, 30, 31, 40, 41, 50, 60 and 70 of FIGS. 1 to 7. For example, in FIG. 1, the piezoelectric film 15 and the transparent electrode 16 are laminated, but as in the piezoelectric sensors 90 and 91 in FIG. 9, the refractive index adjusting layer 92 is laminated between the piezoelectric film 15 and the transparent electrode 16.

As an example, the thickness of the piezoelectric coating layer 14 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 given as an example. Further, 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. With the above thickness and refractive index, the reflectance difference between the transparent electrode 16 and the refractive index adjusting layer 92 becomes 2.0% or less, and the appearance of the piezoelectric sensors 90 and 91 is improved.

[Example 1]
In Example 1, in order to measure the optical characteristics of the piezoelectric sensor 10, a glass substrate was used instead of the display 12 in FIG. 1A, and the total light transmittance and haze were confirmed. The piezoelectric film 15 was prepared 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 Co., Ltd., and had a thickness of 50 μm. The copolymer of vinylidene fluoride, trifluoroethylene, and chlorotrifluoroethylene was Piezotech ^RTTM TS manufactured by Arkema Co., Ltd., and a solution was prepared by ultrasonically in MIBK (methyl isobutyl ketone). Next, a solution of a copolymer of vinylidene fluoride, trifluoroethylene, and chlorotrifluoroethylene was coated on the 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.

Indium tin oxide was formed on both sides of the piezoelectric film 15 by sputtering, and a sheet-shaped transparent packing layer was further attached. The thickness of the indium tin oxide layer was 23 nm. The sheet-shaped transparent packed bed is No. 1 manufactured by Nitto Denko Corporation. It was 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 an alternative to the 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, in order to measure the optical characteristics of the piezoelectric sensor 21, a glass substrate was used instead of the display 12 in FIG. 2A, and the total light transmittance and haze were confirmed. The material used and the method for producing the piezoelectric film 15 are the same as those in the first embodiment. The total light transmittance was 85.0% and the haze was 1.4%.

It should be noted that Example 2 has better total light transmittance and haze than Example 1. FIG. 1A shows the transparent electrode 17 directly formed on the base film 13, while FIG. 2A shows a transparent packed bed 25 between the base film 13 and the transparent electrode 22. It is considered that the surface of the transparent electrode 22 (here, indium tin oxide) has fine irregularities, and the scattering of light can be prevented by covering with the transparent packed bed 25 as shown in FIG. 2 (a).

[Comparative Example 1]
In Comparative Example 1, the transparent packed bed in Example 1 was changed to an air layer, and the total light transmittance and haze were confirmed. The transparent packed bed was not attached to the entire surface of the indium tin oxide, but was attached to the edges of the 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 those of Example 1.

[Comparative Example 2]
In Comparative Example 2, the transparent packed bed 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 those of Example 2.

When the thickness in the above Examples and Comparative Examples was less than 1.0 μm such as the coating layer 14 of the piezoelectric film 15, the cross section was observed and measured using a transmission electron microscope (H-7670, manufactured by Hitachi, Ltd.). .. The thickness of 1.0 μm or more, such as the base film 13, was measured using a film thickness meter (Digital Dial Gauge DG-205 manufactured by Peacock). Furthermore, the total light transmittance and haze were measured using a Direct reading haze computer (HGM-ZDP manufactured by Suga Test Instruments).

Table 1 summarizes the above examples and comparative examples. Comparing Example 1 and Comparative Example 1 and Example 2 and Comparative Example 2, it can be seen that the total light transmittance and haze of each example are better than those of the comparative example, and that the present application has better optical characteristics than the conventional one. The total light transmittance and haze of the piezoelectric film used in the above Examples and Comparative Examples were measured in the same manner as in Examples and the like. The total light transmittance was 91.6% and the haze was 0.9%, which satisfied the total light transmittance of 85% or more and the haze of 5% or less.

As described above, it can be seen that the optical characteristics are improved by using the transparent packed bed instead of the conventional air layer. When the piezoelectric sensor is arranged on the front surface of the display, the piezoelectric sensor of the present application does not easily reduce the visibility of the display.

[Examples 3 to 8]
Further, as shown in FIG. 10, a piezoelectric coating layer 14, 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 the refractive index were measured. The results are shown in Table 2. The "first layer" is the coating layer 14 having piezoelectricity, the "second layer" is the refractive index adjusting layer 92, and the "third layer" is the transparent electrode 16. Except for the formation of the refractive index adjusting layer 92, the same as in the above embodiment.

The refractive index adjusting layer 92 may have a refractive index of 1.54, 1.62, or 1.7, as shown in 2 in the table below. Since the manufacturing method differs depending on the refractive index, each refractive index will be described. When the refractive index is 1.54, a heat-curable resin (refractive index of light) having a weight ratio of 2: 2: 1 of melamine resin: alkyd resin: organic silane condensate on one surface of the coating layer 14 having piezoelectricity. n = 1.54) formed a refractive index adjusting layer 92 having a thickness of 120 nm.

When the refractive index is 1.62, an optically adjusting composition containing 47 parts by mass of an ultraviolet curable resin, 57 parts by mass of zirconia oxide particles (median diameter 40 nm) and PGME on one surface of the piezoelectric coating layer 14. (JSR, "Opster 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 treatment was carried out by irradiating with an ultraviolet ray having 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, TiO ₂ is added to a thermosetting resin (melamine resin: alkyd resin: organic silane condensate = 2: 2: 1 by weight) composed of melamine resin, alkyd resin and organic silane condensate. A resin composition was prepared by mixing fine particles of (refractive index = 2.35). 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. Then, the resin composition was applied onto the piezoelectric coating layer 14, and the resin composition was cured to form a refractive index adjusting layer 92 (refractive index 1.70) having a thickness of 150 nm.

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

In each embodiment, as described above, the thickness of the piezoelectric coating layer 14 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. There is. 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. It is .10. The reflectance difference between the transparent electrode 16 and the refractive index adjusting layer 92 was 2% or less, and the appearance was good.

If necessary, the transparent electrode 16 is etched to become a desired electrode or the like. When determining the refractive index, the portion of the refractive index adjusting layer 92 from which the transparent electrode 16 was removed by etching was used. Therefore, the reflectance difference was obtained by obtaining the reflectance of the air and the transparent electrode 16 and the air and the refractive index adjusting layer 92 from each refractive index.

[Comparative Examples 3 to 4]
As a comparative example with respect to Examples 3 to 8, the case where the refractive index adjusting layer 92 was not present (Comparative Example 3) and the case where the refractive index of the refractive index adjusting layer 92 was smaller than 1.5 (Comparative Example 4) were performed. In the absence of the refractive index adjusting layer 92, the reflectance difference is the difference between the transparent electrode 16 and the piezoelectric coating layer 14. The reflectance difference became larger than 2%, and the appearance became poor.

When the refractive index is 1.46 (Comparative Example 4), the refractive index adjusting layer 92 is obtained by diluting silica sol (Colcoat P, manufactured by Colcoat Co., Ltd.) with ethanol so that the solid content concentration is 2%. A layer having a thickness of 120 nm (SiO ₂ film, refractive index of light 1. 46) was formed to form the refractive index adjusting layer 92. In the comparative example, the manufacturing method of other configurations is the same as that of the embodiment.

From the above, by providing the transparent electrode 16 on the coating layer 14 having piezoelectricity, the transparent electrode 16 may develop a yellow or brown color and impair the appearance. By providing the refractive index adjusting layer 92 as in the present invention and adjusting the thickness and the refractive index of the transparent electrode 16, the refractive index adjusting layer 92, and the piezoelectric coating layer 14 so as to be within the above-mentioned values. As shown in Table 2, it was found that the difference in refractive index can be reduced and the appearance is not impaired. It was found that even if the structure in which the refractive index adjusting layer 92 and the transparent electrode 16 are laminated on the piezoelectric film 15 is arranged on the front surface of the display, the appearance of the display is not spoiled.

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

The piezoelectric sensor of the present invention can be used integrally with a touch panel arranged 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: Piezoelectric Coating layer 15: Piezoelectric film 16, 17, 22: Transparent electrodes 18, 25, 34: Transparent packing layer 24, 33: Laminated body 81: Piezoelectric single film 92: Refractive index adjusting layer 94: Anti-blocking function Hard coat layer

Claims (13)

A piezoelectric sensor located at a position where the image on the front of the display can be visually recognized.
A piezoelectric film in which a piezoelectric coating layer is laminated on a base film, and
A transparent electrode directly or indirectly arranged on at least one surface side of the piezoelectric film,
A transparent packed bed that fills the space between the transparent electrode and the display,
Piezoelectric sensor with. The piezoelectric sensor according to claim 1, wherein the refractive index of the transparent packing layer is a refractive index between the refractive index of the transparent electrode and the refractive index of the display. The piezoelectric sensor according to claim 1 or 2, wherein the transparent packed bed is an adhesive or a resin. The piezoelectric sensor according to any one of claims 1 to 3, wherein the coating layer having piezoelectricity contains a fluororesin. The piezoelectric sensor according to any one of claims 1 to 3, wherein the piezoelectric film having piezoelectricity is a single film containing a fluororesin. The piezoelectric sensor according to claim 4 to 5, wherein the fluororesin is a copolymer of two or more of vinylidene fluoride, trifluoroethylene, and chlorotrifluorotyrene, or a polymer of vinylidene fluoride. The piezoelectric sensor according to any one of claims 1 to 6, which has a refractive index adjusting layer between the base film and the coating layer of the piezoelectric film or at least one 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 adjusting layer has a thickness of 80 to 160 nm, and the transparent electrode has a thickness of 20 nm or more. 7. 8 piezoelectric sensors. The piezoelectric sensor according to claim 4, wherein the piezoelectric sensor has an anchor coat layer between the base film of the piezoelectric film and the coating layer, or on either side of the base film on the opposite side of the coating layer. The piezoelectric sensor according to claim 5, which has an anchor coat layer on either one surface of the piezoelectric single film. The piezoelectric sensor according to any one of claims 1 to 11, wherein a touch panel is arranged on the opposite side of the display in the piezoelectric film. A display provided with the piezoelectric sensor according to any one of claims 1 to 12, wherein the space between the piezoelectric sensor and the display is filled with the transparent packed bed.

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