JP2020047281A - Transparent piezoelectric panel - Google Patents

Abstract

To provide a transparent piezoelectric panel configured to reduce variability in performance of detecting touch pressure using touch positions.SOLUTION: A transparent piezoelectric panel 10A includes first transparent electrodes ES1-ESm, a transparent piezoelectric film 11, and second transparent electrodes EC1-ECn, in this order. When total light transmissivity and total haze value are measured throughout a plane direction in each 1 centimeter square in 10 places, an average of the total light transmissivity is 85% or more and variation coefficient thereof is 30% or less, and an average of the total haze value is 5% or less and variation coefficient thereof is 30% or less.SELECTED DRAWING: Figure 1A

Description

  The present invention relates to a transparent piezoelectric panel.

In recent years, electronic devices, such as smartphones, tablet PCs, and car navigation systems, in which an input device having a touch panel is arranged in front of a display device such as a liquid crystal display, have become widespread. Smartphones and tablet PCs often employ a capacitive touch panel that can perform operations such as tapping, flipping, pinching, dragging, and the like lightly (that is, the operation is comfortable). On the other hand, in a car navigation system, a resistive touch panel that does not easily cause an erroneous operation (that is, has a high degree of certainty in operation) is often used.
Here, if the “position” touched by the user (may be referred to as a touch position in this specification) and its “strength” (in other words, presence / absence of pressing, size (strong / weak), speed, or Change, or a combination thereof) (in this specification, sometimes referred to as touch pressure), if a touch panel capable of detecting both of them is put to practical use, there will be many cases, such as compatibility between the above-mentioned operation comfort and reliability. The advantages are considered. However, a touch panel that has been put into practical use and spread so far can only detect a touch position, but cannot detect a touch pressure.
On the other hand, since the touch panel is installed on the front of the display device, the touch panel is required to have high transparency in order to enhance the visibility of the display on the display device.

Regarding the detection of the touch pressure, for example, in a capacitive touch panel, a technology has been proposed in which a touch pressure is pseudo-detected from the contact area between the finger and the touch panel when the finger is touched. However, in the case of this principle, when touching with a pen, the touch pressure cannot be detected, so that the use scene is limited.
In addition, a technique for detecting pen pressure using a pen capable of detecting a change in electromagnetic induction has been proposed. However, in the case of this principle, a special pen for exclusive use is required, so that the use scene is limited.
Further, a technique for detecting a touch pressure using pressure-sensitive ink has been proposed. However, the use of pressure-sensitive ink reduces the transparency of the touch panel.
In addition, a technology has been proposed that enables a touch pressure to be detected by incorporating or combining a member dedicated to touch pressure detection into a conventional touch panel capable of detecting a touch position such as a resistive film type or a capacitance type. I have. However, incorporating a member dedicated to touch pressure detection is disadvantageous from the viewpoint of reducing the thickness of an electronic device having the touch panel and the viewpoint of manufacturing cost.
Patent Document 1 discloses a piezoelectric layer containing a vinylidene fluoride / tetrafluoroethylene copolymer and a piezoelectric layer containing the vinylidene fluoride / tetrafluoroethylene copolymer as a touch panel that can detect both a touch position and a touch pressure without these problems. There is disclosed a touch panel having a first transparent electrode provided on one surface of the piezoelectric layer and a second transparent electrode provided on the other surface of the piezoelectric layer.

JP 2011-181748 A

As described above, conventionally, a touch panel capable of detecting a touch pressure has been proposed, but it has not been required that the detection performance of the touch pressure varies little depending on the touch position. However, recently, it has been emphasized that touch panels have an excellent feeling in use. The fact that the detection performance of the touch pressure varies depending on the touch position of the touch panel may impair the sense of use of the touch panel.
The touch panel described in Patent Literature 1 has excellent transparency without restricting the method of use, can detect both the touch position and the touch pressure, and does not need to further incorporate a touch pressure detection sensor. Touch panel.
However, the study of the present inventors has revealed that the touch panel described in Patent Literature 1 has a variation in touch pressure detection performance depending on a touch position (that is, in a plane direction of the touch panel).
Therefore, an object of the present invention is to provide a transparent piezoelectric panel in which the detection performance of the touch pressure depending on the touch position has a small variation.

The cause of the variation in the touch pressure detection performance depending on the touch position of the touch panel described in Patent Literature 1 was unknown, but the present inventors have researched to improve the transparency of the transparent piezoelectric film. It has been found that among touch panels having a high touch panel, there is a touch panel having a small variation in touch pressure detection performance in a plane direction.
And, the present inventors, as a result of further investigation, surprisingly,
A first transparent electrode;
A transparent piezoelectric film,
A second transparent electrode;
In this order,
When the total light transmittance and the total haze value are measured at 10 points every 1 cm square over the entire plane direction, the average value of the total light transmittance is 85% or more, and the variation coefficient thereof is 30% or less. And the average value of all the haze values is 5% or less, and the coefficient of variation thereof is 30% or less.
It has been found that the above problem can be solved by a transparent piezoelectric panel.

  This is due to the non-uniform arrangement of piezoelectric elements or piezoelectric films (eg, arrangement under the frame, etc.), the air in the transparent piezoelectric panel, or the rough surface of The presence of wrinkles (e.g., wrinkles) is the main cause of the variation in the detection performance of the touch pressure in the plane direction, and in the transparent piezoelectric panel of the present invention, these are highly advanced by using the total light transmittance and the total haze value as indices. Based on the uniform suppression, it is assumed that the variation in the detection performance of the touch pressure depending on the touch position is suppressed, but the present invention is not limited to this principle.

  The present invention includes the following aspects.

Item 1.
A first transparent electrode;
A transparent piezoelectric film,
A second transparent electrode;
In this order,
When the total light transmittance and the total haze value are measured at 10 points every 1 cm square over the entire plane direction, the average value of the total light transmittance is 85% or more, and the variation coefficient thereof is 30% or less. And the average value of all the haze values is 5% or less, and the coefficient of variation thereof is 30% or less.
Transparent piezoelectric panel.
Item 2.
Item 1. The transparent piezoelectric panel according to Item 1,
A pressure detector,
A position detector,
A touch input device having:
Item 3.
Item 3. An electronic device having the touch input device according to item 2.

  In the transparent piezoelectric panel of the present invention, the total light transmittance and the haze value are highly and uniformly suppressed, and the variation in the touch pressure detection performance depending on the touch position is small.

It is a top view of the transparent piezoelectric panel concerning one embodiment (Embodiment 1) of the present invention. It is a sectional view of a transparent piezoelectric panel concerning one embodiment (Embodiment 1) of the present invention. It is a top view of the transparent piezoelectric panel concerning one embodiment (Embodiment 2) of the present invention. It is sectional drawing of the transparent piezoelectric panel which concerns on one Embodiment (Embodiment 2) of this invention. FIG. 1 is a block diagram illustrating a configuration of a touch input device according to an embodiment of the present invention.

In the present specification, “detection” of “touch position” means determination of a touch position, while “detection” of “touch pressure” means presence / absence of press, speed, magnitude (strong / weak), Or a change thereof, or a combination thereof.
In the present specification, the “average value” is an arithmetic average value, and the “variation coefficient” is calculated based on the arithmetic average value.
As used herein, the term "touch" encompasses touching, being touched, pushing, being pushed, and touching.

  In the present specification, “total light transmittance” is obtained by a light transmittance test using Hazeguard II (product name) (Toyo Seiki Seisakusho) or an equivalent thereof based on ASTM D1003.

  In this specification, the “total haze value” (total haze) is based on a haze (HAZE, turbidity) test using Haze Guard II (product name) (Toyo Seiki Seisakusho) or an equivalent thereof in accordance with ASTM D1003. can get.

  In the present specification, the “inner haze value” refers to a method of measuring the haze value by placing water in a glass cell, inserting a film therein, and measuring the haze value in the method for measuring the total haze value. Is obtained by

  In the present specification, the “outer haze value” (Outer haze) is calculated by subtracting an inward haze value from the entire haze value of the film.

Transparent piezoelectric panel The transparent piezoelectric panel of the present invention is:
A first transparent electrode;
A transparent piezoelectric film,
A second transparent electrode;
In this order,
When the total light transmittance and the total haze value are measured at 10 points every 1 cm square over the entire plane direction, the average value of the total light transmittance is 85% or more, and the variation coefficient thereof is 30% or less. And the average value of all haze values is 5% or less, and the variation coefficient thereof is 30% or less.

The average value of the total light transmittance of the transparent piezoelectric panel of the present invention needs to be 85% or more, preferably 88% or more, and more preferably 90% or more.
The coefficient of variation of the total light transmittance of the transparent piezoelectric panel of the present invention needs to be 30% or less, preferably 20% or less, more preferably 10% or less.

The average value of all the haze values of the transparent piezoelectric panel of the present invention needs to be 5% or less, preferably 3% or less, more preferably 2% or less.
The coefficient of variation of the total haze value of the transparent piezoelectric panel of the present invention needs to be 30% or less, preferably 20% or less, more preferably 10% or less.

  The first transparent electrode may be, for example, an ITO (indium tin oxide) electrode or a tin oxide electrode.

  The thickness of the first transparent electrode is preferably in the range of 0.01 to 0.3 μm.

  The second transparent electrode can be, for example, an ITO (indium tin oxide) electrode or a tin oxide electrode, or a silver nanowire, or a glass electrode.

  The thickness of the second transparent electrode is preferably in the range of 0.01 to 0.3 μm.

The transparent piezoelectric film is, for example, an odd-chain nylon piezoelectric film or a vinylidene fluoride-based piezoelectric film (eg, a vinylidene fluoride / tetrafluoroethylene copolymer piezoelectric film, a vinylidene fluoride / trifluoroethylene copolymer piezoelectric film) Or a polyvinylidene fluoride piezoelectric film).
The “transparent organic piezoelectric film” is a film (polymer film) formed from an organic polymer. The “organic piezoelectric film” may contain components other than the polymer. The “transparent organic piezoelectric film” includes a film including the polymer and a film including the polymer.
The content of the polymer in the “transparent organic piezoelectric film” is preferably 80% by mass or more, more preferably 85% by mass or more, and further preferably 90% by mass. The upper limit of the content is not particularly limited, and may be, for example, 100% by mass or 99% by mass.
The polymer is preferably a vinylidene fluoride polymer.
The transparent piezoelectric film is preferably a vinylidene fluoride-based piezoelectric film, and more preferably a vinylidene fluoride / tetrafluoroethylene copolymer piezoelectric film.
The transparent piezoelectric film such as a vinylidene fluoride-based polymer piezoelectric film may contain an additive usually used for a resin film.

  The “vinylidene fluoride polymer piezoelectric film” is a film composed of a vinylidene fluoride polymer and contains the vinylidene fluoride polymer.

Examples of the "vinylidene fluoride polymer" include:
(1) a copolymer of vinylidene fluoride and one or more monomers copolymerizable therewith; and (2) polyvinylidene fluoride.

Examples of the “monomers copolymerizable therewith” in the “(1) copolymer of vinylidene fluoride and one or more monomers copolymerizable therewith” include trifluoroethylene, tetrafluoroethylene , Hexafluoropropylene, chlorotrifluoroethylene, and vinyl fluoride.
The "one or more monomers copolymerizable therewith" or one of them is preferably tetrafluoroethylene.
Preferred examples of the "vinylidene fluoride-based polymer" include a vinylidene fluoride / tetrafluoroethylene copolymer.
The “vinylidene fluoride / tetrafluoroethylene copolymer” may contain a repeating unit derived from a monomer other than vinylidene fluoride and tetrafluoroethylene, as long as the properties relating to the present invention are not significantly impaired.
The “(1) copolymer of vinylidene fluoride and one or more monomers copolymerizable therewith” includes 50 mol% or more (preferably 60 mol% or more) of repeating units derived from vinylidene fluoride. )contains.
The molar ratio of (repeat units derived from tetrafluoroethylene) / (repeat units derived from vinylidene fluoride) in the “vinylidene fluoride / tetrafluoroethylene copolymer” is preferably from 5/95 to 36/64. Within the range, more preferably within the range of 15/85 to 25/75, even more preferably within the range of 18/82 to 22/78.

The “vinylidene fluoride / tetrafluoroethylene copolymer” may contain a repeating unit derived from a monomer other than vinylidene fluoride and tetrafluoroethylene, as long as the properties relating to the present invention are not significantly impaired. Usually, the content of such a repeating unit is 10 mol% or less. Such a monomer is not limited as long as it can be copolymerized with a vinylidene fluoride monomer and a tetrafluoroethylene monomer.
(1) fluoromonomers (eg, vinyl fluoride (VF), trifluoroethylene (TrFE), hexafluoropropene (HFP), 1-chloro-1-fluoro-ethylene (1,1-CFE), 1-chloro- 2-fluoro-ethylene (1,2-CFE), 1-chloro-2,2-difluoroethylene (CDFE), chlorotrifluoroethylene (CTFE), trifluorovinyl monomer, 1,1,2-trifluorobutene- 4-bromo-1-butene, 1,1,2-trifluorobutene-4-silane-1-butene, perfluoroalkyl vinyl ether, perfluoromethyl vinyl ether (PMVE), perfluoropropyl vinyl ether (PPVE), perfluoroacrylate, 2, 2,2-trifluoroethyl acrylate, 2- (Perfluorohexyl) ethyl acrylate); and (2) hydrocarbon monomers (eg, ethylene, propylene, maleic anhydride, vinyl ether, vinyl ester, allyl glycidyl ether, acrylic acid monomers, methacrylic acid monomers, vinyl acetate) No.

The average value of the total light transmittance of the transparent piezoelectric film is 85% or more, preferably 90% or more, more preferably 92% or more, and further preferably 95% or more. The upper limit of the total light transmittance is not limited, but is usually 99% or less.
The coefficient of variation of the total light transmittance of the transparent piezoelectric film is 30% or less, preferably 10% or less, more preferably 1.0% or less, and further preferably 0.5% or less.

The average value of the total haze value of the transparent piezoelectric film is 5% or less, preferably 3.0% or less, more preferably 2.0% or less, still more preferably 1.5% or less, and even more preferably 1.0% or less. % Or less. The total haze value is preferably as low as possible, and the lower limit is not limited, but is usually 0.1% or more.
The coefficient of variation of the total haze value of the transparent piezoelectric film is 30% or less, preferably 15% or less, more preferably 10% or less, and still more preferably 5.0% or less.

The average value of the external haze value of the transparent piezoelectric film is preferably 1.5% or less, more preferably 1.2% or less, and further preferably 1.0% or less.
The coefficient of variation of the external haze value of the transparent piezoelectric film is preferably 30% or less, more preferably 15% or less, further preferably 10% or less, and particularly preferably 5.0% or less.

The average value of the internal haze value of the transparent piezoelectric film is preferably 1.0% or less, more preferably 0.9% or less, and further preferably 0.8% or less.
The coefficient of variation of the internal haze value of the transparent piezoelectric film is preferably 30% or less, more preferably 15% or less, further preferably 10% or less, and particularly preferably 5.0% or less.

  The thickness of the transparent piezoelectric film is usually in the range of 3 to 100 μm, preferably in the range of 6 to 50 μm, more preferably in the range of 9 to 40 μm, and still more preferably in the range of 10 to 30 μm.

The transparent piezoelectric film, for example,
Step A of polarizing a non-polarized polymer film (eg, a non-polarized vinylidene fluoride-based polymer film); and heat-treating a subsequent polarized polymer film (eg, a polarized vinylidene fluoride-based polymer film) Step B
And a method for producing a transparent piezoelectric film.

Step A (polarization step)
In the step A, the non-polarized polymer film is subjected to a polarization treatment.

  The “non-polarized polymer film” used in the step A can be produced by a known method such as a casting method, a hot press method, or a melt extrusion method. The “non-polarized polymer film” used in Step A is preferably a film manufactured by a casting method. The polymer constituting the non-polarized polymer film is, as understood by those skilled in the art, the polymer described for the “transparent piezoelectric film”.

The manufacturing method of the "non-polarized polymer film" by the casting method, for example,
(1) a step of preparing a liquid composition by dissolving or dispersing a polymer (eg, a vinylidene fluoride-based polymer) and a desired component in a solvent;
(2) a step of casting (applying) the liquid composition on a substrate; and (3) a step of vaporizing the solvent to form a film.

The dissolution temperature in the preparation of the liquid composition is not particularly limited, but it is preferable to increase the dissolution temperature because dissolution can be promoted. However, if the dissolution temperature is too high, the resulting film tends to be colored, so the dissolution temperature is preferably from room temperature to 80 ° C.
From the viewpoint of preventing such coloring, preferred examples of the solvent include ketone solvents (eg, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), acetone, diethyl ketone, dipropyl ketone), ester solvents ( Examples include ethyl acetate, methyl acetate, propyl acetate, butyl acetate, ethyl lactate), ether solvents (eg, tetrahydrofuran, methyltetrahydrofuran, dioxane), and amide solvents (eg, dimethylformamide (DMF), dimethylacetamide). Can be These solvents may be used alone or in combination of two or more. As the solvent, an amide-based solvent which is a solvent widely used for dissolving polyvinylidene fluoride (PVDF) may be used, but the content of the amide-based solvent in the solvent is desirably 50% or less.

  The liquid composition is cast (coated) on a substrate by a knife coating method, a cast coating method, a roll coating method, a gravure coating method, a blade coating method, a rod coating method, an air doctor coating method, or a slot die method. What is necessary is just to carry out based on the conventional methods, such as. Among them, the gravure coating method or the slot die method is preferred in terms of easy operability, small variation in the thickness of the obtained film, and excellent productivity. As the substrate, for example, a polyethylene terephthalate (PET) film can be used.

The solvent can be vaporized by a conventional drying method such as heating.
The drying temperature in the evaporation of the solvent can be appropriately determined depending on the type of the solvent and the like, but is usually in the range of 20 ° C to 200 ° C, preferably in the range of 40 ° C to 170 ° C.
The drying temperature may be a constant temperature or may be changed. By changing the drying temperature from a low temperature (eg, 40 to 100 ° C.) to a high temperature (eg, 120 to 200 ° C.), the haze value of the obtained film can be reduced. This can be achieved, for example, by dividing the drying zone into several zones and moving the film (or the cast solution before film formation) into the cold zone and into the hot zone.
Specifically, for example, the drying zone may be divided into four zones of 50 ° C, 80 ° C, 120 ° C, and 150 ° C, and the film may be continuously moved from the 50 ° C zone to the 150 ° C zone.
The drying time in the evaporation of the solvent is usually in the range of 1 to 600 seconds, preferably in the range of 10 to 200 seconds.

The “non-polarized polymer film (eg, non-polarized vinylidene fluoride polymer film)” (hereinafter sometimes simply referred to as “non-polarized film”) used in step A is preferably stretched. Not something. Also, preferably, the non-polarized film is not stretched in the manufacturing method. That is, the transparent piezoelectric film is preferably a non-stretched piezoelectric film.
The transparent piezoelectric film thus obtained has high uniformity in thickness. More specifically, preferably, the transparent piezoelectric film has a coefficient of variation in thickness measured at 10 points in every 1 cm square over the entire film of not more than 20% of the average film thickness.

  The non-polarized film used in the step A may be a film that has been subjected to a heat treatment after the formation.

  The thickness of the non-polarized film used in the step A may be determined according to the piezoelectric film to be obtained.

  The polarization treatment in the step A can be performed by a conventional method such as a corona discharge treatment.

The polarization treatment in the step A is preferably performed by corona discharge.
Either a negative corona or a positive corona may be used for the corona discharge, but it is desirable to use a negative corona from the viewpoint of easy polarization of the non-polarized resin film.

The corona discharge treatment is not particularly limited. For example, as described in Japanese Patent Application Laid-Open No. 2011-181748 (Patent Document 1), application is performed on a non-polarized film using a linear electrode; By applying a needle-shaped electrode to the polarizing film.
The conditions of the corona discharge treatment may be appropriately set based on common sense in the technical field to which the present invention belongs. If the conditions of the corona discharge treatment are too weak, the piezoelectricity of the resulting piezoelectric film may be insufficient, while if the conditions of the corona discharge treatment are too strong, the resulting piezoelectric film may have point-like defects. is there.
For example, when continuous application is performed by roll-to-roll using a linear electrode, the distance varies between the linear electrode and the non-polarized film, the film thickness, and the like. DC electric field. The processing speed is, for example, 10 to 500 cm / min.

  Alternatively, the polarization treatment may be performed by, for example, sandwiching the non-polarized film between both surfaces of the non-polarized film with a plate electrode and applying the voltage in addition to corona discharge. Specifically, for example, when the application is performed by sandwiching the non-polarized film between both surfaces with a flat plate electrode, a DC electric field of 0 to 400 MV / m (preferably 50 to 400 MV / m) and 0.1 seconds to 60 minutes Can be adopted.

Step B (heat treatment step)
Step B is performed after step A. In step B, a polarized polymer film (eg, a polarized vinylidene fluoride polymer film) obtained by the polarization treatment in step A (hereinafter, may be simply referred to as a polarized film) is heat-treated.
The heat treatment in the step B can be performed on the polarized film or on the portion where the polarization has been completed in the step A. That is, while performing the polarization process in step A, the heat treatment in step B may be performed on the portion where the polarization process has been completed.
The method of the heat treatment is not particularly limited. For example, the polarizing film is sandwiched between two metal plates and the metal plate is heated; the roll of the polarizing film is heated in a thermostat; In the production of polarized films in a roll mode, heating a metal roller and contacting the polarized film with the heated metal roller; or roll-to-roll in a furnace in which the polarized film is heated. It can be done by passing through. At this time, the polarized film may be heat-treated alone, or may be laminated on another kind of film or metal foil to form a laminated film and heat-treated. In particular, when heat treatment is performed at a high temperature, the latter method is preferable because the polarized film is less likely to wrinkle.
The temperature of the heat treatment may vary depending on the type of the polarized film to be heat-treated, and is preferably in the range of (melting point of the polarized film to be heat-treated -100) ° C to (melting point of the polarized film to be heat-treated +40) ° C. Is within.
Specifically, the temperature of the heat treatment is preferably 80 ° C. or higher, more preferably 85 ° C. or higher, and further preferably 90 ° C. or higher.
The temperature of the heat treatment is preferably 170 ° C. or lower, more preferably 160 ° C. or lower, and further preferably 140 ° C. or lower.
The time of the heat treatment is usually at least 10 seconds, preferably at least 0.5 minutes, more preferably at least 1 minute, further preferably at least 2 minutes.
Although the upper limit of the heat treatment time is not limited, usually, the heat treatment time is 60 minutes or less.
The condition of the heat treatment is preferably at 90 ° C. or more for 1 minute or more.
In the present specification, the melting point of the film is a maximum value in a heat of fusion curve obtained when the temperature is increased at a rate of 10 ° C./min using a differential scanning calorimeter (DSC).

  After the heat treatment, the non-polarized polymer film is cooled to a predetermined temperature. The temperature is preferably in the range from 0 ° C to 60 ° C and can be room temperature. The cooling rate may be slow cooling or rapid cooling, and rapid cooling is preferable in terms of productivity. The quenching can be performed, for example, by means such as blowing.

  Further, the transparent piezoelectric film may be a known method, a film manufactured according to the method, or a commercially available film.

The structure of the transparent piezoelectric panel of the present invention is not limited as long as it has a first transparent electrode, a transparent piezoelectric film, and a second transparent electrode in this order, and may have other members. .
Examples of the other members include a pressure-sensitive adhesive layer and a base film described in a second embodiment of the present invention described below.
Such another member has an average value of the total light transmittance of the transparent piezoelectric panel of the present invention of 85% or more, a coefficient of variation thereof of 30% or less, and an average value of all haze values of 5 or less. And that the coefficient of variation thereof is 30% or less may be selected and used as an index.
Examples of such a pressure-sensitive adhesive layer include a pressure-sensitive adhesive layer formed from an acrylic pressure-sensitive adhesive and having a thickness in the range of 0.01 to 20 μm described in a second embodiment of the present invention described below. .
Further, as such a base film, a PET film having a thickness in the range of 10 to 100 μm is exemplified.
The thickness of the transparent piezoelectric panel of the present invention is generally in the range of 1 to 1000 μm, preferably in the range of 1 to 100 μm, and more preferably in the range of 1 to 50 μm.

  When the transparent piezoelectric panel of the present invention (e.g., a touch panel (preferably, a touch panel capable of detecting a touch pressure)) is pressed with a finger or the like, the transparent piezoelectric panel of the present invention responds to a temporal change in strain of the transparent piezoelectric film. Since an electrical signal can be obtained, the presence / absence of pressing, speed, size (strength or weakness), a change thereof, or a combination thereof can be determined by using the transparent piezoelectric panel of the present invention. Here, the magnitude of the pressing (that is, the static pressure) can be determined using the integral value of the electric signal.

In the transparent piezoelectric panel of the invention, one or more (preferably two) transparent piezoelectric films can be used.
When two or more (preferably two) transparent piezoelectric films are used, the two or more transparent piezoelectric films may be bonded to each other by an adhesive sheet. The pressure-sensitive adhesive sheet is not particularly limited as long as the transparent piezoelectric films can be bonded to each other, and can be composed of one or two or more layers. That is, when the pressure-sensitive adhesive sheet is composed of one layer, the pressure-sensitive adhesive sheet is composed of a pressure-sensitive adhesive layer, and when the pressure-sensitive adhesive sheet is composed of two or more layers, both outer layers are pressure-sensitive adhesive layers. When the pressure-sensitive adhesive sheet is composed of three or more layers, the pressure-sensitive adhesive sheet may have a base material layer as an inner layer.
The pressure-sensitive adhesive layer may be, for example, a layer containing an acrylic pressure-sensitive adhesive as a pressure-sensitive adhesive.
The substrate layer may be a transparent film, and preferably, for example, a polyimide, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyparaphenylene sulfide, or polyamideimide film.

For example, the transparent piezoelectric panel of the present invention (eg, a touch panel (preferably, a touch panel capable of detecting a touch pressure)) is preferably
A first transparent electrode;
A first transparent piezoelectric film;
An adhesive sheet,
A second transparent piezoelectric film;
A second transparent electrode;
In this order.
The first transparent electrode is disposed on an outer surface of the first transparent piezoelectric film, and the second transparent electrode is disposed on an outer surface of the second transparent piezoelectric film.

  Although the transparent piezoelectric film may have pyroelectricity, in the transparent piezoelectric panel according to the embodiment of the present invention, the first transparent piezoelectric film and the second transparent piezoelectric film are charged with the same polarity by temperature rise (for example, , Positive charges and positive charges) are arranged on the outside, and a potential difference between the two surfaces is obtained as an electric signal between the first transparent electrode and the second transparent electrode. Electric signals due to electrical properties are reduced, and electric signals due to piezoelectricity can be selectively obtained.

In the transparent piezoelectric panel of the present invention, in order to reduce the electric signal due to the pyroelectricity (that is, the pyroelectric signal) (in other words, to cancel the pyroelectricity), the first transparent piezoelectric film and the first transparent piezoelectric film are used. It is preferable that the transparent piezoelectric films of No. 2 have the same level of piezoelectric constant d33. Further, it is preferable that the piezoelectric constant d33 of the same level possessed by both of the transparent piezoelectric films is lower because the electric signal due to pyroelectricity can be reduced to a higher degree. Specifically, both of the transparent piezoelectric films have a piezoelectric constant d33 of preferably 25 pC / N or less, more preferably 20 pC / N or less, and still more preferably 8 pC / N or less.
In order to sufficiently obtain an electric signal due to piezoelectricity (that is, a piezoelectric signal) while canceling pyroelectricity (in other words, not to cancel piezoelectricity), the first transparent piezoelectric film, and It is preferable to make a difference in the thickness of the second transparent piezoelectric film. Specifically, the ratio of the thickness of the first transparent piezoelectric film to the thickness of the second transparent piezoelectric film is preferably 1.1 times or more, more preferably 1.5 times or more, so that the piezoelectric signal can be increased. .

In the transparent piezoelectric panel of the present invention, the detection of the touch pressure is performed by reading a voltage value or a current value through a detection circuit, which differs depending on whether the detection electric circuit is in a voltage mode or a charge mode. In the detection,
(1) reading the voltage or charge generated from the film as it is, or (2) amplifying and reading the charge or voltage by the detection circuit,
Either can be adopted.
If noise is a problem in the detection,
(1) shielding electromagnetic waves that cause noise to remove noise; and / or (2) generally cutting off charge or voltage below a certain value because noise is smaller than a signal.
Etc. can be adopted.
In the case of the transparent piezoelectric panel of the present invention, a pyroelectric signal may be added to the noise source, but the cut-off setting of the above (2) can be performed as a cutting method. To cancel the pyroelectric signal more positively,
(1) As the first transparent piezoelectric film and the second transparent piezoelectric film, adopting a bimorph structure in which two films having opposite poling directions are opposed to each other,
(2) A pyroelectric signal is reduced by using a film having a low piezoelectric constant d33 as the first transparent piezoelectric film and the second transparent piezoelectric film, and / or (3) the first transparent piezoelectric film. And a method of canceling the pyroelectric signal by incorporating a pyroelectric element for generating a pyroelectric signal equivalent to the pyroelectric signal of the second transparent piezoelectric film.
In the detection, a differential signal may be read, or an integrated signal may be read. In the transparent piezoelectric panel of the present invention, the piezoelectric signal and the pyroelectric signal are generated as differential signals with respect to pressure or heat, but are preferably read as integrated signals in order to accurately obtain gradation with respect to pressure. When reading as an integration signal, the integration time can be set arbitrarily, but is desirably set between 1 μs and 10 min, preferably between 1 ms and 1 min.

  Hereinafter, embodiments of the transparent piezoelectric panel of the present invention will be described with reference to the drawings. Members common to the drawings may be denoted by the same reference numerals.

FIG. 1A is a plan view of a transparent piezoelectric panel according to an embodiment (Embodiment 1) of the present invention.
FIG. 1B shows a cross-sectional view of a transparent piezoelectric panel according to one embodiment (Embodiment 1) of the present invention. FIG. 1B is a cross-sectional view along the transparent electrode EC1 in FIG. 1A.

The transparent piezoelectric panel 10A is
M first transparent electrodes ES1 to ESm arranged in the X direction;
A transparent piezoelectric film 11,
N second transparent electrodes EC1 to ECn arranged in the Y direction;
In this order.
The first transparent electrodes ES <b> 1 to ESm are arranged on one main surface of the transparent piezoelectric film 11.
The second transparent electrodes EC1 to ECn are arranged on the other main surface of the transparent piezoelectric film 11.
In FIG. 1B, the first transparent electrodes ES1 to ESm are covered with a protective layer 12, and the second transparent electrodes ES1 to ECn are covered with a protective layer 13. The protective layer is not always necessary.

The transparent piezoelectric panel of the aspect, for example,
Forming a first transparent electrode and a second transparent electrode on the transparent piezoelectric film by sputtering, respectively;
Patterning the first transparent electrode and the second transparent electrode by etching,
It can be manufactured by a manufacturing method having

FIG. 2A shows a plan view of a transparent piezoelectric panel according to another embodiment (Embodiment 2) of the present invention.
FIG. 2B is a sectional view of a transparent piezoelectric panel according to another embodiment (Embodiment 2) of the present invention. FIG. 2B is a cross-sectional view along the transparent electrode EC1 in FIG. 2A.

The transparent piezoelectric panel 10B
A first base film 16;
M first transparent electrodes ES1 to ESm arranged in the X direction;
A first pressure-sensitive adhesive layer 14,
A transparent piezoelectric film 11,
N second transparent electrodes EC1 to ECn arranged in the Y direction with the second adhesive layer 15;
A second base film 17;
In this order.

The first pressure-sensitive adhesive layer 14 is disposed on one main surface of the transparent piezoelectric film 11,
The first transparent electrodes ES1 to ESm are arranged on the first pressure-sensitive adhesive layer 14,
The first base film 16 is disposed on the first transparent electrodes ES1 to ESm.

The second pressure-sensitive adhesive layer 15 is disposed on the other main surface of the transparent piezoelectric film 11,
The second transparent electrodes EC1 to ECn are arranged on the second adhesive layer 15,
The second base film 17 is disposed on the second transparent electrodes EC1 to ECn.
The thickness of the pressure-sensitive adhesive layers 14 and 15 is usually in the range of 0.01 to 20 μm as a distance from the surface of the transparent piezoelectric film 11 to the first base film 16 or the second base film 17. It is.
The thickness of the first base film 16 and the second base film 17 is usually in the range of 10 to 100 μm.

  In FIG. 1A, the first transparent electrodes ES1 to ESm are covered with a protective layer 12, and the second transparent electrodes ES1 to ECn are covered with a protective layer 13. The protective layer is not always necessary.

The transparent piezoelectric panel of the aspect, for example,
A step of preparing two base film with a transparent electrode (eg, a PET film with an ITO electrode);
A step of patterning the transparent electrodes of the two base films with a transparent electrode by etching, and a step of etching the two base films with the transparent electrodes with the transparent electrodes etched using an adhesive on the main surface of the transparent piezoelectric film, respectively. It can be manufactured by a manufacturing method having a step of sticking.

Known materials used for the transparent piezoelectric panel can be used as the materials for the pressure-sensitive adhesive layer, the transparent electrode, and the base film.
As the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer, for example, an acrylic pressure-sensitive adhesive can be used.
The transparent electrode can be, for example, those exemplified above.
Examples of the base film include a polyethylene terephthalate resin film (PET film), a polyethylene naphthalate resin film (PEN film), a polycarbonate resin film (PC film), a polyether sulfone resin film (PES film), and a cyclic olefin resin. A coalesced resin film (COP film) is exemplified. Among them, a PET film or a PEN film is preferable.

  In the transparent piezoelectric panel of the present invention, the detection of the touch pressure is performed by the voltage or the current value passed through the detection circuit, and these are different depending on whether the detection electric circuit is in the voltage mode or the charge mode, but the transparent piezoelectric panel of the present invention is the same. The coefficient of variation of each value in the panel surface when the touch pressure is applied is preferably in the range of 0 to 30%.

  The planar size of the transparent piezoelectric panel of the present invention is not particularly limited, but is preferably in the range of 3 to 40 inches.

The transparent piezoelectric panel of the present invention is capable of detecting a touch position in addition to detecting a touch pressure. Therefore, the touch pressure and the touch position can be detected without combining with the touch position detecting touch panel.
The transparent piezoelectric panel of the present invention can be a touch panel.
The transparent piezoelectric panel of the present invention can be, for example, a transparent piezoelectric panel of a resistive film type or a capacitance type.

  The transparent piezoelectric panel of the present invention can be used for, for example, a touch input device or a touch sensor device.

Touch input device The touch input device of the present invention,
A transparent piezoelectric panel of the present invention,
A pressure detector,
A position detector,
Having.
The input device is capable of performing an input based on a touch position, a touch pressure, or both (eg, an input based on a magnitude of pressure (strength) such as writing pressure).

FIG. 3 is a block diagram showing a configuration of the touch input device according to one embodiment of the present invention.
The touch input device 2 includes a transparent piezoelectric panel 1 and a signal processing unit 3 that processes an output signal of the transparent piezoelectric panel 1. The transparent piezoelectric panel 1 is the transparent piezoelectric panel of the present invention.
When a touch operation is performed on the transparent piezoelectric panel 1, an electromotive force is generated in a portion of the transparent piezoelectric film 11 corresponding to the touch position, and a voltage signal is output from one of the first transparent electrodes ES1 to ESm, and The signal is input to the signal processing unit 3 via one of the second transparent electrodes EC1 to ECn.
The position detecting unit 4 shown in FIG. 3 can detect a touch position on the transparent piezoelectric panel 1 based on the electrode to which the voltage signal has been input. The detection of the touch position by the position detection unit 4 can be performed in the same manner as in a conventional transparent piezoelectric panel of a resistive film type or a capacitive type.
The pressure detection unit 5 detects a touch pressure based on a voltage signal generated when the piezoelectric body 11 is pressed.
The input device can be used for an electronic device.

Touch sensor device The touch sensor device of the present invention,
A transparent piezoelectric panel of the present invention,
A pressure detector,
A position detector,
Having.
In the above, the touch input device of the present invention has been described, but the description can be similarly applied to the touch sensor device.

Electronic device The electronic device of the present invention is:
It has a touch input device or a touch sensor device of the present invention.
The electronic device having the touch input device or the touch sensor device performs an operation and / or an operation based on a touch position, a touch pressure or both (for example, in paint software, a thickness of a line displayed on a screen according to a pen pressure). , Etc.).
Examples of the electronic device having the touch input device include a smartphone, a tablet PC, a digitizer, a touch pad, a car navigation system, and a touch panel display (touch panel monitor) such as an FA (Factory Automation) device.
Examples of the electronic device having the touch sensor device include a collision sensor and a robot cleaner.
The electronic device may include the touch input device of the present invention, or the touch sensor device of the present invention, or may include the touch input device of the present invention or the touch sensor device of the present invention.

  Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

A 30 μm-thick vinylidene fluoride / tetrafluoroethylene copolymer piezoelectric film was prepared, and PET films with ITO (ITO / PET) (ITO layer thickness: 0.05 μm, PET film thickness , With the matrix transparent electrode facing the piezoelectric film side and an adhesive (thickness of adhesive layer: 10 μm) to produce a transparent piezoelectric panel. By pressing with a finger from above and using a multiplexer, the touch position (XY position) could be detected, and at the same time, the touch pressure (press) could be detected from the magnitude of the electrical signal.
In addition, in order to evaluate the variation of the quantitative detection output and the optical performance (total light transmittance and total haze) depending on the position in the panel plane, the position on the panel is divided into 10 sections each having a width of 10 mm (vertical A to J). , Horizontal 1 to 10), a total of 100 divisions were selected at random, and the detection output with respect to the touch pressure was measured together with the optical performance (Table 1). The touch pressure was represented by a load value obtained by freely dropping a weight with a constant load from a constant height (20 mm) in order to make the conditions uniform.

1: Transparent piezoelectric panel 2: Touch input device 3: Signal processing unit 4: Position detecting unit 5: Pressure detecting unit 10A: Transparent piezoelectric panel 10B: Transparent piezoelectric panel 11: Transparent piezoelectric film 12: Protective layer 13: Protective layer 14: First pressure-sensitive adhesive layer 15: Second pressure-sensitive adhesive layer 16: First base film 17: Second base film ES1 to ESm: First transparent electrode EC1 to ECn: Second transparent electrode

Claims (3)

A first transparent electrode;
A transparent piezoelectric film,
A second transparent electrode;
In this order,
When the total light transmittance and the total haze value are measured at 10 points every 1 cm square over the entire plane direction, the average value of the total light transmittance is 85% or more, and the variation coefficient thereof is 30% or less. And the average value of all the haze values is 5% or less, and the coefficient of variation thereof is 30% or less.
Transparent piezoelectric panel. A transparent piezoelectric panel according to claim 1,
A pressure detector,
A position detector,
A touch input device having: An electronic apparatus comprising the touch input device according to claim 2.