JP2013206444A - Electrostatic capacity touch sensor with plastic cover - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic capacity touch sensor with a plastic cover that has excellent detection sensitivity, transmittance, and rigidity.SOLUTION: An electrostatic capacity touch sensor with a plastic cover of the present invention includes: a transparent protective cover that contains ultra fine glass particles dispersed in a plastic plate; a film sensor of a capacitance method that is arranged on a rear face of the protective cover; and an adhesive layer that is provided between the protective cover and the film sensor, and bonds both members with each other.

Description

  The present invention relates to a capacitive touch sensor with a cover in which a capacitive film sensor is bonded to the back surface of a protective cover attached to a liquid crystal display unit of an electronic device, and particularly detection sensitivity and transmittance while being a plastic cover. It is excellent in rigidity.

  Usually, PDAs, handheld terminals and other portable information terminals, copy machines, facsimile and other office automation equipment, smartphones, mobile phones, portable game devices, electronic dictionaries, car navigation systems, small PCs, digital cameras, video cameras, portable MDs (PMD) A protective cover is attached to a liquid crystal display window of an electronic device or the like to protect it. Conventionally, this protective cover has a black frame-shaped light shielding layer formed on the peripheral edge of the back surface of a transparent glass substrate.

  In addition, touch panels are often used in the above-described electronic devices, and among several types of touch panels, a multi-touch function that enlarges / reduces an image by operations such as hitting, flipping, and picking a screen with a fingertip, Capacitive touch panels are popular because of their excellent visibility and durability.

  An example of a capacitive touch panel is disclosed in Patent Document 1. In Patent Document 1, the touch panel further includes a light-transmitting protective cover that functions as a dielectric on the viewer side of the capacitive film sensor, that is, on the side opposite to the display device. . The protective cover is bonded onto the film sensor via an adhesive layer. This protective cover functions as an input surface (touch surface, contact surface) to the touch panel. That is, information can be input from the outside to the touch panel by bringing a conductor such as a human finger into contact with the protective cover.

JP 2010-198103 A

  However, in the case of a cover glass, there is a problem that it is heavy (heavy specific gravity), easily broken by impact, and low cost is difficult in terms of mass productivity. On the other hand, plastic covers do not have these problems, but instead have low detection sensitivity due to low dielectric constant, poor visibility due to low transmittance, and lack of rigidity, which makes them easy to bend. It was.

  Accordingly, an object of the present invention is to solve the above-described problems, and to provide a capacitive touch sensor with a plastic cover that is excellent in detection sensitivity, transmittance, and rigidity.

  According to a first aspect of the present invention, there is provided a transparent protective cover containing ultrafine glass particles dispersed in a plastic plate, a capacitive film sensor disposed on the back surface of the protective cover, and the protective cover. The present invention provides a capacitive touch sensor with a plastic cover, which is provided between the film sensor and an adhesive layer that bonds the two members together.

  According to a second aspect of the present invention, there is provided a capacitive touch sensor with a plastic cover according to the first aspect, wherein the plastic plate is made of a resin of PMMA, PC or COP.

  The third aspect of the present invention provides the capacitive touch sensor with a plastic cover according to the first aspect or the second aspect, wherein the ultrafine glass particles have a particle size of 0.3 μm or less.

  Moreover, the 4th aspect of this invention provides the electrostatic capacitance touch sensor with a plastic cover in any one of the 1st-3rd aspect whose dispersion degree of the said ultrafine glass particle is 5 to 30%.

  The fifth aspect of the present invention provides the capacitive touch sensor with a plastic cover according to any one of the first to fourth aspects, wherein the base film of the film sensor is made of any resin of PET, PC, or COP. To do.

  Moreover, the 6th aspect of this invention provides the electrostatic capacitance touch sensor with a plastic cover of the 1st-5th aspect in which the said protective cover has a decoration part in a back surface peripheral part.

  According to the configuration of the present invention, since the plastic cover contains the ultrafine glass particles dispersed in the plastic plate, the dielectric constant can be increased and the detection sensitivity is increased. Moreover, the transmittance | permeability rose because the refractive index of the plastic cover became small, and as a result, visibility improved. Furthermore, the rigidity has increased and it has become difficult to bend, and the surface strength has been improved. Therefore, a capacitive touch sensor with a protective cover having both the advantages of a cover glass and a plastic cover could be obtained.

It is sectional drawing which shows an example of the electrostatic capacitance touch sensor with a protective cover of this invention with a display apparatus. It is a top view which shows the touch sensor of FIG.

[First embodiment]
Hereinafter, an embodiment of a capacitive touch sensor with a plastic cover according to the present invention will be described with reference to the drawings.

  The touch sensor 20 shown in FIG. 1 includes a protective cover 12 containing ultrafine glass particles 12b dispersed in a plastic plate 12a, a capacitive film sensor 30 disposed on the back surface of the protective cover 12, An adhesive layer 14 is provided between the protective cover 12 and the film sensor 30 and bonds the two members together.

  Examples of the resin used for the plastic plate 12a of the protective cover 12 include heat such as polymethyl methacrylate (PMMA), polycarbonate (PC), cyclic olefin polymer (COP), alicyclic methacrylate, and HEMA hydroxyethyl methacrylate (PHEMA). A thermoplastic resin that can be softened and fluidized and molded with a mold and hardens when cooled can be used. In addition, thermosetting resins that chemically change into a net-like molecular structure by heat, such as diethylene glycol diallyl carbonate (ADC) and siloxanyl methacrylate (SiMA), and photo-curing resins that cure at room temperature with ultraviolet rays or the like may be used. it can. Among these, PMMA and PC are generally well known as representative examples of transparent plastics used for optics. PMMA is excellent in transparency, birefringence, which is an optical distortion, is small, and PC has high heat resistance. In recent years, COPs having transparency, low birefringence, heat resistance, low hygroscopicity and the like have been widely used. The thickness of the plastic plate 2a is 0.2 mm to 2 mm.

  As a molding method of the plastic plate 12a, there are injection molding, cast molding, roll molding, compression molding, extrusion molding, and the like. An appropriate molding method is adopted depending on the resin material to be used and the shape to be made.

Examples of the ultrafine glass particles 12b in the protective cover 12 include (1) a mixture of lead oxide, boron oxide, and silicon oxide (PbO—B ₂ O ₃ —SiO ₂ system), (2) zinc oxide, and oxidation. A mixture of boron and silicon oxide (ZnO—B ₂ O ₃ —SiO ₂ system), (3) lead oxide, boron oxide, silicon oxide, aluminum oxide (PbO—B ₂ O ₃ —SiO ₂ —Al ₂ O ₃ system) (4) Lead oxide, zinc oxide, boron oxide, silicon oxide (PbO—ZnO—B ₂ O ₃ —SiO ₂ type) mixture, (5) Bismuth oxide, boron oxide, silicon oxide (Bi ₂ O ₃₎ -B ₂ O ₃ mixtures -SiO ₂ system), (6) zinc oxide, a mixture of phosphorous oxide, silicon oxide _{(ZnO-P 2 O 5 -SiO} 2 system), (7) zinc oxide, boron oxide, potassium oxide (ZnO Mixture of B ₂ O ₃ -K ₂ O system), (8) phosphorylation, boron oxide, a mixture of aluminum oxide _{(P 2 O 5 -B 2 O} 3 -Al 2 O 3 system), (9) zinc oxide, Mixture of phosphorus oxide, silicon oxide, aluminum oxide (ZnO—P ₂ O ₅ —SiO ₂ —Al ₂ O ₃ system), (10) zinc oxide, phosphorus oxide, titanium oxide (ZnO—P ₂ O ₅ —TiO ₂ system) ), (11) a mixture of zinc oxide, boron oxide, silicon oxide, potassium oxide (ZnO—B ₂ O ₃ —SiO ₂ system—K ₂ O system), (12) zinc oxide, boron oxide, silicon oxide, potassium oxide, a mixture of calcium oxide _{(ZnO-B 2 O 3 -SiO} 2 -K 2 O-CaO -based), (13) zinc oxide, boron oxide, silicon oxide, potassium oxide, calcium oxide, aluminum oxide (Z _{O-B 2 O 3 -SiO 2} -K 2 O-CaO-Al mixture 2 _{O 3} system), (14) lead oxide, zinc oxide, boron oxide, barium oxide, silicon oxide _(PbO-ZnO-B 2 O ₃ -BaO-SiO ₂ -based), (15) barium oxide, calcium oxide, silicon oxide (BaO-CaO-SiO ₂ -based) and the like.

  The ultrafine glass particles 12b preferably have a refractive index of 1.5 to 1.65. In general, a glass material has a refractive index of about 1.5 to 1.9, but when the ultrafine glass particles 12b are dispersed in the plastic plate 12a as in the present invention, the average refraction of the resin component. When the refractive index is significantly different from the refractive index of the ultrafine glass particles 12b, reflection / scattering at the interface between the ultrafine glass particles 12b and the resin component is increased, resulting in poor transparency. Since the refractive index of a general resin is 1.45 to 1.7 (PMMA: 1.49, PC: 1.59, COP: 1.52), the refractive index of the ultrafine glass particles 12b and the resin component In order to match these, it is preferable to set the refractive index of the ultrafine glass particles 12b to 1.5 to 1.65.

  The particle diameter of the ultrafine glass particles 12b is 0.3 μm or less, which is smaller than the wavelength of visible light so that light scattering does not occur.

  Further, when the ultrafine glass particles 12b are surface-treated with a silane coupling agent, the protective cover 12 having excellent rigidity and impact resistance can be obtained by firmly bonding to the polymerized and cured resin component.

  The degree of dispersion of the ultrafine glass particles 12b is preferably 5 to 30%. If the degree of dispersion of the ultrafine glass particles 12b is less than 5%, the strength, refractive index, and dielectric constant are almost the same as those of conventional plastic covers, and if it exceeds 30%, molding processing is difficult and impact resistance. Is inferior.

  As the adhesive layer 14 for affixing the capacitive film sensor 30 to the back surface of the protective cover 12, layers made of materials having various adhesive properties can be used. OCA (Optical Clear Adhesive: highly transparent adhesive) is preferable. In the present specification, “adhesion (layer)” is used as a concept including adhesion (layer).

  An example of the capacitive film sensor 30 disposed on the back surface of the protective cover 2 will be described below.

  As shown in FIG. 1, the film sensor 30 includes a base film 32, a first electrode portion 40 provided on a surface 32 a on one side (observer side) of the base film 32, and the base film 32. 2nd electrode part 45 provided on the surface 32b of the other side (display apparatus 15 side). The first electrode portion 40 includes a first conductor 41 arranged in a predetermined pattern on the surface 32a on one side (observer side) of the base film 32. The second electrode portion 45 has a second conductor 46 arranged in a predetermined pattern on the surface 32b on the other side (the display device 15 side) of the base film 32. As described above, the film sensor 30 is disposed on the display panel of the display device 15. The base film 32, the first conductor 41, and the second conductor 46 have translucency, and the observer can observe the image displayed on the display device 15 through these. .

  The base film 32 functions as a dielectric, and for example, PET, PC, COP, PVC, or the like may be used. In particular, the COP film is preferable because it not only has excellent optical isotropy, but also has excellent dimensional stability and, in turn, processing accuracy. The thickness of the base film 31 may be 20 μm to 3 mm.

  The base film 31 preferably has a refractive index equivalent to that of the protective cover 2. When the refractive index of the base film 31 of the film sensor 3 is significantly different from the refractive index of the protective cover 2, the interface between the base film 31 of the film sensor 3 and the adhesive layer 4, or between the adhesive layer 4 and the protective cover 2. Reflection / scattering at the interface is increased and transparency is deteriorated. Incidentally, the refractive indexes of the above-mentioned resins mentioned as specific examples of the base film 31 are PET (1.58), PC (1.59), COP (1.52), and PVC (1.52).

  The first conductor 41 and the second conductor 46 are made of a conductive material (for example, ITO (indium tin oxide)) and configured to detect the contact position of the outer conductor 5 with the protective cover 12. The detection control unit 25 is electrically connected to the detection circuit. As shown in FIG. 2, the first conductor 41 is composed of a plurality of linear conductors arranged in one direction along the film surface of the base film 32. The second conductor 46 is composed of a plurality of linear conductors arranged side by side in the other direction along the film surface of the base film 32 intersecting with the one direction. In the present embodiment, one direction that is the arrangement direction of the first conductors 41 and the other direction that is the arrangement direction of the second conductors 46 are orthogonal to each other on the film surface of the base film 32.

  As shown in FIG. 2, each of a large number of first conductors 41 included in the first electrode portion 40 extends linearly in a direction intersecting with the arrangement direction (the one direction). Similarly, each of the multiple second conductors 46 included in the second electrode portion 45 extends linearly in a direction intersecting with the arrangement direction (the other direction). In particular, in the illustrated example, each first conductor 41 included in the first electrode portion 40 extends linearly along a direction (the other direction) orthogonal to the arrangement direction (the one direction), Each second conductor 46 included in the two-electrode portion 45 extends linearly along a direction (the one direction) orthogonal to the arrangement direction (the other direction).

  In the present embodiment, the first conductor 41 included in the first electrode portion 40 includes a line portion 42 that extends linearly and a bulging portion 43 that bulges from the line portion 42. In the illustrated example, the line portion 42 extends linearly along a direction that intersects the arrangement direction of the first conductors 41. The bulging portion 43 is a portion that bulges from the line portion 42 along the film surface of the base film 32. Therefore, the width of the first conductor 41 is thicker at the portion where the bulging portion 43 is provided. As shown in FIG. 2, in the present embodiment, the first conductor 41 has an outer contour having a substantially square shape in plan view at the bulging portion 43.

  The second conductor 46 included in the second electrode portion 45 is configured similarly to the first conductor 41 included in the first electrode portion 40. That is, the second conductor 46 included in the second electrode portion 45 has a line portion 47 extending linearly and a bulging portion 48 bulging from the line portion 47. In the illustrated example, the line portion 47 extends linearly along a direction that intersects with the arrangement direction of the second conductors 46. The bulging portion 48 is a portion that bulges from the line portion 47 along the film surface of the base film 32. Therefore, the width of the second conductor 46 is thicker at the portion where the bulging portion 48 is provided. As shown in FIG. 2, in the present embodiment, the second conductor 46 has an outer contour having a substantially square shape in plan view at the bulging portion 48.

  In addition, as shown in FIG. 2, when observed from the normal direction of the film surface of the base film 32 (that is, in plan view), each first conductor 41 included in the first electrode portion 40 has a second It intersects with a number of second conductors 46 included in the electrode part 45. The bulging portion 43 of the first electrode portion 40 is disposed on the first conductor 41 between the intersections of two adjacent second conductors 46. Similarly, when observed from the normal direction of the film surface of the base film 32, each of the second conductors 46 included in the second electrode portion 45 includes a large number of first conductors 41 included in the first electrode portion 40. Intersects. The bulging portion 48 of the second electrode portion 45 is also disposed on the second conductor 46 between the intersections of the two adjacent first conductors 41. Furthermore, in the present embodiment, the bulging portion 43 of the first conductor 41 included in the first electrode portion 40 and the bulging portion 48 of the second conductor 46 included in the second electrode portion 45 are based on It arrange | positions so that it may not overlap, when it observes from the normal line direction of the film surface of the material film 32. FIG. That is, when observed from the normal direction of the film surface of the base film 32, the first conductor 41 included in the first electrode portion 40 and the second conductor 46 included in the second electrode portion 45 are each conductive. They intersect only at the line portions 42 and 47 of the bodies 41 and 46.

  In addition, on the surface 32a on one side and the surface 32b on the other side of the base film 32, an external lead wire 36 having conductivity is formed. One or two external lead wires 36 are provided for each of the conductors 41 and 46 of the electrode portions 40 and 45 depending on the contact position detection method. The external lead wire 36 is made of a conductive material. Then, one end of the corresponding external lead wire 36 is electrically connected to both ends of each conductor 41, 46 (see FIG. 2). Each external lead-out line 36 is electrically connected at the other end to a detection circuit of a detection control unit (not shown) configured to detect the contact position of the external conductor with respect to the display surface 12. That is, the conductors 41 and 46 of the electrode portions 40 and 45 are electrically connected to the detection circuit that detects the contact position via the external lead wire 36. The external lead-out line 36 extends on the base film 32 in the non-display area A2 and does not extend in the display area A1. Therefore, the external lead-out line 36 does not need to be formed from a light-transmitting material, and can be formed from a highly conductive metal such as silver or copper.

[Example of changes]
In addition, this invention is not limited to the said embodiment. For example, the protective cover 12 may have the decoration part 50 in the back surface peripheral part. The decoration unit 50 conceals the external lead-out line 36 of the film sensor 30 or expresses a product name logo or the like. As a formation means of the decoration part 50, you may print directly on the protective cover 12, and you may bond the decorating film separately printed on the film. Further, a color resist pattern may be provided as one configuration of the film sensor 30 and used as the decorative portion 50.

  In the first embodiment, ITO is exemplified as the material of the first conductor 41 and the second conductor 46, but indium oxide, antimony-added tin oxide, fluorine-added tin oxide, aluminum-added zinc oxide, potassium Addition zinc oxide, silicon addition zinc oxide, metal oxide materials such as zinc oxide-tin oxide system, indium oxide-tin oxide system, zinc oxide-indium oxide-magnesium oxide system, zinc oxide, tin oxide film, or tin, Metal materials such as copper, aluminum, nickel, and chromium can be given, and two or more of these may be formed in combination.

  In the first embodiment, the first conductor 41 and the second conductor 46 are made of ultrafine conductive carbon fibers such as carbon nanotubes, carbon nanohorns, carbon nanowires, carbon nanofibers, graphite fibrils, or silver materials. A composite material in which conductive fibers are dispersed in a polymer material functioning as a binder can be used. Here, as the polymer material, a conductive polymer such as polyaniline, polypyrrole, polyacetylene, polythiophene, polyphenylene vinylene, polyphenylene sulfide, poly p-phenylene, polyheterocyclic vinylene, PEDOT: poly (3,4-ethylenedioxythiophene) should be adopted. Can do. In addition, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetheretherketone (PEEK), polycarbonate (PC), polypropylene (PP), polyamide (PA), acrylic, polyimide, Non-conductive polymers such as epoxy resins, phenol resins, aliphatic cyclic polyolefins, norbornene-based thermoplastic transparent resins can be employed.

  The external lead line 36 may be made of the same material as the first conductor 41 and the second conductor 46, or may be formed using a silver paste or the like.

  Moreover, in 1st Embodiment, although it has the 1st conductor 41 and the 2nd conductor 46 on both surfaces of the base film 32, the film sensor 30 of this invention is not limited to this. For example, a base film having a first conductor on one side and another base film having a second conductor on one side may be bonded together. Furthermore, what has a 1st conductor and a 2nd conductor on the single side | surface of a base film, and insulated the intersection area | region with the insulating layer may be used. Moreover, what formed only the 1st conductor on the single side | surface of a base film may be used.

  Further, the projected capacitive touch sensor of the present invention may be either a self-capacitance (Self Capacitance) method or a mutual capacitance (Mutual Capacitance) method.

  The technical contents and technical features of the present invention have been disclosed as described above. However, those skilled in the art to which the present invention belongs will not depart from the technical idea of the present invention based on the teachings and disclosure of the present invention. Various substitutions and additions can be made. Accordingly, the scope of protection of the present invention is not limited to that disclosed in the examples, and includes various substitutions and additions that are not different from the present invention, and is included in the scope of the appended claims. is there.

5 Finger 10 Input / output device 12 Protective cover 12a Plastic plate 12b Ultra fine glass particles 14 Adhesive layer 15 Display device 19 Adhesive layer 20 Capacitive touch sensor with plastic cover 30 Film sensor 32 Base film 32a Surface (surface on one side) )
32b surface (surface on the other side)
36 External Lead Wire 40 First Electrode Part 41 First Conductor 42 Line Part 43 Swelling Part 45 Second Electrode Part 46 Second Conductor 47 Line Part 48 Swelling Part 50 Decoration Part

Claims (6)

A protective cover containing ultrafine glass particles dispersed in a plastic plate;
A capacitive film sensor disposed on the back surface of the protective cover;
An adhesive layer provided between the protective cover and the film sensor, and bonding both members;
A capacitive touch sensor with a plastic cover, characterized by comprising:   The capacitive touch sensor with a plastic cover according to claim 1, wherein the plastic plate is made of a resin of PMMA, PC, or COP.   The capacitive touch sensor with a plastic cover according to claim 1, wherein the ultrafine glass particles have a particle size of 0.3 μm or less.   The electrostatic capacity touch sensor with a plastic cover according to claim 1, wherein a degree of dispersion of the ultrafine glass particles is 5 to 30%.   The capacitive touch sensor with a plastic cover according to any one of claims 1 to 4, wherein the base film of the film sensor is made of a resin selected from PET, PC, and COP. The electrostatic capacity touch sensor with a plastic cover according to claim 1, wherein the protective cover has a decorative portion on the peripheral edge of the back surface.

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