JP2015075893A - Piezoelectric body, touch panel and electronic device - Google Patents

Abstract

A touch panel capable of detecting a touch position and a touch pressure with high accuracy is provided. A touch panel includes a piezoelectric body. The piezoelectric body 21 includes a plurality of piezoelectric blocks corresponding to the detection unit area of the touch panel 2, and each piezoelectric block is partitioned from each other by a cut C that suppresses deformation propagation to the adjacent piezoelectric block. [Selection] Figure 2

Description

  The present invention relates to a piezoelectric body and a touch panel using the same.

  In recent years, electronic devices in which an input device having a touch panel is arranged on the front surface of a display device such as a liquid crystal display, such as smartphones, tablet PCs, and car navigation systems, have become widespread. Smartphones and tablet PCs often employ capacitive touch panels that can easily perform operations such as tapping, flipping, pinching, and dragging (that is, high operational comfort). On the other hand, in a car navigation system, many resistive film type touch panels are employed in which erroneous operations are unlikely to occur (that is, operation reliability is high).

  Here, if the “position” touched by the user (sometimes referred to herein as a touch position) and its “strength” (in other words, presence or absence of pressure, strength, speed, or a combination thereof) ( If a touch panel capable of detecting both of them (which may be referred to as “touch pressure” in this specification) is put to practical use, many advantages such as compatibility of the above-described comfort and certainty of operation can be considered.

  Therefore, a touch panel having a piezoelectric body has been proposed (for example, Patent Document 1). When the piezoelectric body is pressed, the piezoelectric body generates a voltage corresponding to the temporal displacement of strain at the time of pressing. Utilizing this property, the technique according to Patent Document 1 can detect not only the touch position (XY axis) but also the touch pressure (Z axis) by using a piezoelectric body.

  FIG. 7 is a plan view showing the touch panel 101 disclosed in Patent Document 1. As shown in FIG. As shown in FIG. 7, the touch panel 101 has m transparent electrodes ES1 to ESm arranged in the X direction and n transparent electrodes EC1 to ECn arranged in the Y direction.

  FIG. 8 is a cross-sectional view of the touch panel 101 along the transparent electrode EC1. As shown in FIG. 8, the touch panel 101 includes a piezoelectric body 102, transparent electrodes ES <b> 1 to ESm are provided on one surface of the piezoelectric body 102, and transparent electrodes EC <b> 1 to ECn are provided on the other surface of the piezoelectric body 102. ing. The transparent electrodes ES1 to ESm are covered with a protective film 103, and the transparent electrodes EC1 to ECn are covered with a protective film 104.

  When a touch operation is performed on the touch panel 101, a portion corresponding to the touch position of the piezoelectric body 102 is deformed to generate a voltage, and a voltage signal is applied to the two transparent electrodes corresponding to the touch position. The touch position and the touch pressure on the touch panel 101 can be detected based on the position of the transparent electrode to which the voltage signal is applied and the magnitude of the voltage.

JP 2006-163619 A

  However, in the technique according to Patent Document 1, since the deformation (deflection) of the piezoelectric body 102 due to pressing extends to the periphery of the touch position, a voltage is applied not only to the transparent electrode corresponding to the touch position but also to the adjacent transparent electrode. Will be. Therefore, there is a problem that the detection sensitivity of the touch position and the touch pressure is low.

  Therefore, an object of the present invention is to provide a touch panel that can detect a touch position and a touch pressure with high accuracy.

As a result of intensive studies, the present inventors have
A piezoelectric body used for a touch panel,
A plurality of piezoelectric blocks corresponding to the detection unit region of the touch panel;
It has been found that each of the piezoelectric blocks can solve the above problem by a piezoelectric body that is partitioned from each other by a deformation propagation suppressing structure that suppresses deformation propagation to an adjacent piezoelectric block.

The present invention includes the following aspects.
[Claim 1]
A piezoelectric body used for a touch panel,
A plurality of piezoelectric blocks corresponding to the detection unit region of the touch panel;
Piezoelectric bodies in which each piezoelectric block is partitioned from each other by a deformation propagation suppressing structure that suppresses deformation propagation to an adjacent piezoelectric block.
[Section 2]
The piezoelectric body according to Item 1, wherein the deformation propagation suppressing structure is a break formed in the piezoelectric body.
[Section 3]
The piezoelectric body according to Item 1, wherein the deformation propagation suppressing structure is a groove that separates the piezoelectric blocks from each other.
[Claim 4]
Item 4. The piezoelectric body according to any one of Items 1 to 3, comprising an organic piezoelectric film.
[Section 5]
Item 5. The piezoelectric body according to Item 4, wherein the organic piezoelectric film is a vinylidene fluoride film.
[Claim 6]
Item 5. The piezoelectric body according to Item 4, wherein the organic piezoelectric film is a vinylidene fluoride / tetrafluoroethylene copolymer film.
[Claim 7]
A touch panel comprising the piezoelectric body according to any one of Items 1 to 6.
[Section 8]
An electronic device comprising the touch panel according to Item 7.

  ADVANTAGE OF THE INVENTION According to this invention, the touch panel which can detect a touch position and a touch pressure with high precision can be provided.

It is a block diagram showing the composition of the touch input device concerning one embodiment of the present invention. (A) And (b) is sectional drawing of the touchscreen which concerns on embodiment of this invention. FIG. 3 is a plan view of the touch panel shown in FIG. 2. It is a partial expanded sectional view of a piezoelectric material, (a) shows the state before pressing, and (b) shows the state at the time of pressing. (A) And (b) is sectional drawing of the touchscreen which concerns on the modification of embodiment of this invention. It is a top view of the touch panel shown in FIG. It is a top view of the conventional touch panel. It is sectional drawing of the conventional touch panel.

In this specification, “detection” of “touch position” means determination of touch position, while “detection” of “touch pressure” means presence / absence of pressure, speed, magnitude, or a combination thereof. Means the decision.

  FIG. 1 is a block diagram showing a configuration of a touch input device 1 according to an embodiment of the present invention. The touch input device 1 includes a touch panel 2 and a signal processing unit 3 that processes an output signal of the touch panel 2, and includes a mobile phone (eg, a smartphone), a personal digital assistant (PDA), a tablet PC, a digitizer, and a touch. It is incorporated in electronic devices such as pads, ATMs, automatic ticket vending machines, and car navigation systems.

  The touch panel 2 is configured to be able to detect a touch position and a touch pressure, and includes m transparent electrodes ES1 to ESm arranged in the X direction and n transparent electrodes EC1 to ECn arranged in the Y direction. Have. One end of each of the transparent electrodes ES1 to ESm and EC1 to ECn is connected to the signal processing unit 3. The signal processing unit 3 includes a position detection unit 4 that detects a touch position on the touch panel 2 and a pressure detection unit 5 that detects a touch pressure.

  2A is a cross-sectional view taken along the transparent electrode EC1 of the touch panel 2, and FIG. 2B is a cross-sectional view taken along the transparent electrode ES1 of the touch panel 2. The touch panel 2 includes a sheet-like piezoelectric body 21, transparent electrodes ES <b> 1 to ESm are provided on one surface of the piezoelectric body 21, and transparent electrodes EC <b> 1 to ECn are provided on the other surface of the piezoelectric body 21. The transparent electrodes ES1 to ESm are covered with a protective film 22, and the transparent electrodes EC1 to ECn are covered with a protective film 23.

  The piezoelectric body 21 can be a transparent or opaque piezoelectric body, and is preferably a transparent piezoelectric body.

The piezoelectric body 21 can be an inorganic piezoelectric film or an organic piezoelectric film. Examples of inorganic piezoelectric films include quartz piezoelectric films (wafers), LiNbO ₃ piezoelectric films, LiTaO ₃ piezoelectric films, KNbO ₃ piezoelectric films, ZnO piezoelectric films, AlN piezoelectric films, and PZT (PbZrO ₃ —PbTiO ₃ based solid solution system materials). A piezoelectric film etc. are mentioned. Examples of organic piezoelectric films include odd-chain nylon piezoelectric films, vinylidene fluoride polymer piezoelectric films (eg, vinylidene fluoride / tetrafluoroethylene copolymer films, vinylidene fluoride / trifluoroethylene copolymer films, Polyvinylidene fluoride film) and polylactic acid.

  The vinylidene fluoride polymer film is preferably a vinylidene fluoride / tetrafluoroethylene copolymer film.

  The “vinylidene fluoride polymer film” may contain an additive usually used for a resin film.

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

As an example of the “vinylidene fluoride polymer”,
(1) A copolymer of vinylidene fluoride and one or more monomers copolymerizable therewith; and (2) Polyvinylidene fluoride is mentioned. “(1) Vinylidene fluoride and copolymerized therewith” Examples of “monomers copolymerizable therewith” in “Copolymers with one or more possible monomers” include trifluoroethylene, tetrafluoroethylene, hexafluoropropylene, chlorotrifluoroethylene, and vinyl fluoride. Is mentioned.

  The “one or more monomers copolymerizable therewith” or one of them is preferably tetrafluoroethylene.

  Preferable examples of the “vinylidene fluoride polymer” include a vinylidene fluoride / tetrafluoroethylene copolymer.

  The “vinylidene fluoride / tetrafluoroethylene copolymer” may contain repeating units derived from monomers 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” contains 50 mol% or more (preferably 60 mol% or more) of repeating units derived from vinylidene fluoride. )contains.

  The molar ratio of (a repeating unit derived from tetrafluoroethylene) / (a repeating unit derived from vinylidene fluoride) in the “vinylidene fluoride / tetrafluoroethylene copolymer” is preferably 5/95 to 36/64. Within the range, more preferably within the range of 15/85 to 25/75, still 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 of the present invention are not significantly impaired. Usually, the content of such repeating units is 10 mol% or less. Such a monomer is not limited as long as it is copolymerizable with a vinylidene fluoride monomer or a tetrafluoroethylene monomer.
(1) Fluoromonomer (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- (2) hydrocarbon monomers (eg, ethylene, propylene, maleic anhydride, vinyl ether, vinyl ester, allyl glycidyl ether, acrylic acid monomers, methacrylic acid monomers, vinyl acetate) It is done.

  The organic piezoelectric film of the present invention has a total light transmittance of 90% or more.

  The total light transmittance of the organic piezoelectric film of the present invention is preferably 92% or more, more preferably 95% or more. The upper limit of the total light transmittance is not limited, but the total light transmittance of the organic piezoelectric film of the present invention is usually 99% or less.

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

  The total haze value of the organic piezoelectric film of the present invention is preferably 3.0% or less.

  The total haze value of the organic piezoelectric film of the present invention is more preferably 2.0% or less, still more preferably 1.5% or less, and particularly preferably 1.0% or less. The lower the total haze value, the better. The lower limit is not limited, but the total haze value of the organic piezoelectric film of the present invention is usually 0.2% or more.

  In this specification, “total haze” is based on ASTM D1003 and is determined by haze (HAZE, turbidity) test using Hazeguard II (product name) (Toyo Seiki Seisakusho) or its equivalent. can get.

  The internal haze value of the organic piezoelectric film of the present invention is preferably 1.2% or less.

  The internal haze value of the organic piezoelectric film of the present invention is more preferably 1.0% or less, still more preferably 0.9% or less, and particularly preferably 0.8% or less. The lower the internal haze value, the better. The lower limit is not limited, but the internal haze value of the organic piezoelectric film of the present invention is usually 0.1% or more.

  In the present specification, “inner haze” means that in the method for measuring the total haze value, water is put into a glass cell, a film is inserted therein, and the haze value is measured. Is obtained.

  The external haze value of the organic piezoelectric film of the present invention is preferably 1.5% or less, more preferably 1.2% or less, and still more preferably 1.0% or less. The lower the external haze value, the better. The lower limit is not limited, but the external haze value of the organic piezoelectric film of the present invention is usually 0.1% or more.

  In the present specification, the “outer haze value” (outer haze) is calculated by subtracting the internal haze value from the total haze value of the film.

  The thickness of the organic piezoelectric film of the present invention 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 thickness of the piezoelectric body 21 is usually 1 to 200 μm, preferably 1 to 100 μm, more preferably 1 to 50 μm. From the viewpoint of transparency, the thickness is preferably thinner, and thicker is preferred when piezoelectricity is important. Based on these facts, the thickness of the piezoelectric body 21 can be appropriately set according to its use.

  The transparent electrodes ES1 to ESm and the transparent electrodes EC1 to ECn may be, for example, an ITO (indium tin oxide) electrode or a tin oxide electrode.

  When a touch operation is performed on the touch panel 2, a voltage is generated in a portion corresponding to the touch position of the piezoelectric body 21, and the voltage signal is any of the transparent electrodes ES1 to ESm and any of the transparent electrodes EC1 to ECn. The signal is input to the signal processing unit 3 via. The position detection unit 4 illustrated in FIG. 1 can detect the touch position on the touch panel 2 based on the electrode to which the voltage signal is input.

  Furthermore, in the present embodiment, a plurality of cuts C (deformation propagation suppressing structures) are formed in the piezoelectric body 21. As shown in FIG. 3, the cuts C are formed in a lattice shape. Specifically, the cut C extending in the X direction of the piezoelectric body 21 is formed between the transparent electrodes EC1 to ECn, and the cut C extending in the Y direction of the piezoelectric body 21 is formed between the transparent electrodes ES1 to ESm. It is formed in the middle. The piezoelectric body 21 is partitioned into a plurality of piezoelectric blocks 211 by the lattice-shaped cuts C.

  In FIG. 3, the transparent electrodes EC1 to ECn are indicated by broken lines, the transparent electrodes ES1 to ESm are indicated by alternate long and short dash lines, and in the central region of each piezoelectric block 211, the transparent electrodes ES1 to ESm, the transparent electrodes EC1 to ECn, Intersect. That is, each piezoelectric block 211 corresponds to a detection unit area of the touch panel 2.

  4A and 4B are partially enlarged cross-sectional views of the piezoelectric body 21. FIG. 4A shows a state before pressing, and FIG. 4B shows a state during pressing. As shown in FIG. 4A, the cut C has a V-shaped cross section. Three piezoelectric blocks defined by the two cuts C are designated 211a, 211b, and 211c from the left side, respectively.

  When pressure is applied to the piezoelectric block 211b by a touch operation, the piezoelectric block 211b is elastically deformed to generate a voltage, as shown in FIG. 4B. At this time, in the cut C, one side surface is displaced to the other side surface, and the width of the cut C becomes narrow, but the other side surface does not move. Therefore, the piezoelectric blocks 211a and 211c adjacent to the piezoelectric block 211b are not deformed and no voltage is generated. That is, the break C suppresses deformation propagation from the piezoelectric block 211b to the adjacent piezoelectric blocks 211a and 211c. Therefore, the voltage signal is applied only to the transparent electrode corresponding to the piezoelectric block 211b, and the voltage signal is not applied to the transparent electrodes corresponding to the adjacent piezoelectric blocks 211a and 211c. Therefore, the position detection unit 4 and the pressure detection unit 5 shown in FIG. 1 can detect the touch position and the touch pressure with high accuracy, respectively.

  As described above, in the touch panel 2 according to the present embodiment, since the cut C defining the piezoelectric block 211 is formed in the piezoelectric body 21, the piezoelectric blocks 211a and 211c adjacent to the pressed piezoelectric block 211b are not deformed. The voltage of the piezoelectric block is generated only in the detection unit region corresponding to the touch position. Therefore, the touch position and the touch pressure can be detected with high accuracy.

  Note that the cross-sectional shape of the cut C is not particularly limited as long as it is a shape capable of suppressing deformation propagation to the adjacent piezoelectric block, and may be, for example, a U-shape or a concave shape. Also, the size (depth, width) of the cut C is not particularly limited as long as it can suppress the propagation of deformation to the adjacent piezoelectric block and is not visually recognized.

  Further, in addition to the above-described form in which a cut is formed in the piezoelectric body, it is possible to adopt a form in which each piezoelectric block is disposed separately from each other. This form will be described below.

  FIG. 5 shows a cross-sectional structure of a touch panel 2 ′ according to a modification of the present embodiment. FIG. 5 (a) is a cross-sectional view along the transparent electrode EC1, and FIG. 5 (b) is along the transparent electrode ES1. FIG. The touch panel 2 'has a configuration in which the piezoelectric body 21 is replaced with the piezoelectric body 21' in the touch panel 2 shown in FIG. The piezoelectric body 21 ′ is provided with a groove T penetrating the piezoelectric body 21 ′ in the thickness direction instead of the cut C.

  FIG. 6 is a plan view showing the piezoelectric body 21 ′. As shown in FIG. 6, the grooves T are formed in a lattice shape like the cut lines C. Specifically, the groove T extending in the X direction of the piezoelectric body 21 ′ is formed between the transparent electrodes EC1 to ECn, and the groove T extending in the Y direction of the piezoelectric body 21 ′ is formed from the transparent electrodes ES1 to ESn. It is formed in the middle of ESm. By the lattice-shaped grooves T, the piezoelectric body 21 ′ is partitioned into a plurality of piezoelectric blocks 211 ′ corresponding to the detection unit area of the touch panel 2 ′.

  In the above configuration, since the grooves T are provided between the piezoelectric blocks 211 ′, the piezoelectric blocks 211 ′ are separated from each other by the grooves T. Therefore, even if one of the piezoelectric blocks 211 'is pressed and elastically deformed, the adjacent piezoelectric block 211' is not deformed. Therefore, a voltage signal is applied only to the transparent electrode corresponding to the pressed piezoelectric block 211 '. Therefore, the touch position and the touch pressure can be detected with high accuracy.

  The width of the groove T is not particularly limited as long as deformation propagation to the adjacent piezoelectric block can be suppressed and is not visually recognized.

  As described above, since the touch panel according to the present embodiment partitions the piezoelectric body into a plurality of piezoelectric blocks by cuts or grooves, the touch position and the touch pressure can be detected with high accuracy.

  In addition, the structure which divides a piezoelectric block mutually is not limited to a cut | interruption and a groove | channel, if it is a structure which suppresses a deformation | transformation propagation to an adjacent piezoelectric block. In addition, the touch panel according to the present invention can use any type of touch panel such as a resistive film type and a capacitance type as long as it has a piezoelectric body.

  The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the claims, and a form obtained by appropriately combining technical means disclosed in the embodiment is also included in the present invention. Included in the technical scope.

DESCRIPTION OF SYMBOLS 1 Touch input device 2 Touch panel 2 'Touch panel 3 Signal processing part 4 Position detection part 5 Pressure detection part 21 Piezoelectric body 21' Piezoelectric body 22 Protection film 23 Protection film 211 Piezoelectric block 211 'Piezoelectric block 211a Piezoelectric block 211b Piezoelectric block 211c Piezoelectric block C cut (deformation suppression structure)
T groove (deformation propagation suppression structure)

Claims (8)

A piezoelectric body used for a touch panel,
A plurality of piezoelectric blocks corresponding to the detection unit region of the touch panel;
Piezoelectric bodies in which each piezoelectric block is partitioned from each other by a deformation propagation suppressing structure that suppresses deformation propagation to an adjacent piezoelectric block.   The piezoelectric body according to claim 1, wherein the deformation propagation suppressing structure is a cut formed in the piezoelectric body.   The piezoelectric body according to claim 1, wherein the deformation propagation suppressing structure is a groove that separates the piezoelectric blocks from each other.   The piezoelectric body according to claim 1, comprising an organic piezoelectric film.   The piezoelectric body according to claim 4, wherein the organic piezoelectric film is a vinylidene fluoride film.   The piezoelectric body according to claim 4, wherein the organic piezoelectric film is a vinylidene fluoride / tetrafluoroethylene copolymer film.   A touch panel comprising the piezoelectric body according to claim 1.   An electronic device comprising the touch panel according to claim 7.

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