JP2012221468A - Touch panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a touch panel in which its upper film substrate does not deform inappropriately even if and because the upper film substrate dilates due to changes in temperature or humidity, by using a simple configuration.SOLUTION: A touch panel 10 comprises a lower substrate 12 and an upper film substrate 16 which is attached to the lower substrate 12 via an adhesion means 14 in a frame-like shape. The adhesion means 14 comprises a foam body 18 in a frame-like shape, a first adhesive layer 20 bonded to a first surface of the foam body 18, and a second adhesive layer 22 bonded to a second surface of the foam body 18.

Description

  The present invention relates to a resistive film type touch panel in which conductive film surfaces are arranged to face each other.

  In a conventional resistive film type touch panel, an upper film substrate and a lower substrate are bonded together using a frame-shaped double-sided adhesive tape or adhesive. FIG. 12 is an exploded perspective view showing a schematic configuration of such a touch panel 100, and FIG. 13 is a cross-sectional view of the touch panel 100 of FIG. For the sake of clarity, the thickness direction of the touch panel (the vertical direction in FIG. 13) is expanded from the actual dimensional relationship. The touch panel 100 includes a lower substrate 102 made of glass or the like and an upper film substrate 106 made of PET or the like attached to the lower substrate 102 through a frame-like adhesive layer 104. As the adhesive layer 104, a double-sided adhesive tape or an adhesive is usually used.

  As shown in FIG. 12, the entire circumference of the upper film substrate 106 is usually fixed by a frame-shaped adhesive layer 104. When the upper film substrate 106 expands due to a change in temperature and humidity, the upper film substrate 106 has a higher expansion coefficient than the lower substrate 102. Therefore, as shown in FIG. May end up. When such a deformation occurs, an input is not detected even if a touch operation is performed with a predetermined pressing force, or conversely, conductive films (not shown) provided on the upper film substrate 106 and the lower substrate 102, respectively. 1), even if they do not touch each other, malfunctions such as contact (short) may occur.

  In order to prevent the waviness, for example, Patent Document 1 discloses an information input display device including a stretching action unit that generates an outward stretching force on a film by elasticity.

JP 2003-296023 A

  In the invention described in Patent Document 1, it is necessary to separately provide a stretching action unit that applies a stretching force that pulls the film outward, which complicates the configuration of the entire touch panel. Moreover, since it is necessary to provide the exterior member 13 provided with the inclination part 13a of an appropriate angle, the dimension of the thickness direction of a touchscreen increases, and the screen area of a touchscreen is reduced somewhat by the exterior member 13. FIG.

  Further, like the touch panel 200 shown in FIG. 15, a leader line 202 such as an FPC is attached only to the lower substrate 204 (glass), and the entire periphery of the upper film substrate 208 is fixed by a frame-like adhesive layer 206. In other cases (when the FPC is not the type in which the FPC is sandwiched between the substrates), other problems due to the difference in thermal expansion (thermal contraction) rate between the members may occur. That is, in the touch panel as shown in FIG. 15, the glass substrate 204 and the PET film 208 are bonded to each other by a conductive adhesive or the like in the conductive bonding portion 210 in order to electrically connect the upper film substrate 208 (PET film) and the FPC 202. The PET film 208 contracts more than the glass 204 due to cooling after the heat treatment in the manufacturing process. At this time, as shown in FIG. 16, due to the shrinkage of the PET film 208, the film-side electrode 212 formed on the PET film 208 may be broken (cracked) and may be disconnected.

  Therefore, the present invention provides a touch panel that realizes that the upper film substrate does not deform or break inappropriately due to a difference in expansion coefficient between the upper film substrate and the lower film substrate using a simpler configuration. The purpose is to provide.

  In order to achieve the above object, the invention described in claim 1 uses an upper film substrate and a lower substrate each provided with a conductive film surface coated with a transparent conductive material, using a frame-like bonding means. In the touch panel in which the conductive film surfaces are bonded to each other, the bonding means includes a frame-shaped foam and a first surface bonded to the first surface facing the lower substrate of the foam. There is provided a touch panel including a first adhesive layer and a second adhesive layer bonded to a second surface facing the upper film substrate of the foam.

  The invention described in claim 2 provides the touch panel according to claim 1, wherein the adhesive means is a double-sided adhesive tape having a foam as a base material.

  The invention according to claim 3 provides the touch panel according to claim 1 or 2, wherein the foam is made of a polyurethane material, a polyolefin material, or an acrylic foam.

  According to a fourth aspect of the present invention, in the touch panel according to any one of the first to third aspects, the thickness of the foam is not less than 0.2 mm and not more than 0.6 mm, and the first and second Provided is a touch panel in which each of the adhesive layers has a thickness of 10 μm or more and 40 μm or less.

The invention according to claim 5 is the touch panel according to any one of claims 1 to 4, wherein the density of the foam is 240 kg / m ³ or more and 700 kg / m ³ or less, and the compression of the foam A touch panel is provided in which the load is 0.008 MPa or more and 0.032 MPa or less, and the compression residual strain of the foam is 2% or more and 4% or less.

  According to the sixth aspect of the present invention, an upper film substrate and a lower substrate each provided with a conductive film surface formed by depositing a transparent conductive material are arranged so that the conductive film surfaces face each other using a frame-like bonding means. In the touch panel formed by bonding, the bonding means includes a frame-shaped film, a third pressure-sensitive adhesive layer bonded to a third surface facing the lower substrate of the frame-shaped film, and the And a fourth adhesive layer bonded to a fourth surface facing the upper film substrate of the frame-shaped film, and the linear expansion coefficient of the frame-shaped film is equal to the linear expansion coefficient of the upper film substrate. Thus, the frame-shaped film provides a touch panel that is arranged such that the stretching axis of the frame-shaped film is in the same direction as the stretching axis of the upper film substrate.

  According to a seventh aspect of the present invention, in the touch panel according to the sixth aspect, the adhesive force of the third adhesive layer is shifted in the plane direction in a state where the expanded frame-shaped film is attached to the lower substrate. Provided is a touch panel set to such an extent that it can be performed.

  The invention according to claim 8 is the touch panel according to any one of claims 1 to 7, wherein the upper film substrate and the lower substrate are electrically connected by a conductive adhesive, and the upper film In the substrate, a touch panel is provided in which a slit is provided between a conductive adhesive portion of the conductive adhesive and a touch input region.

  According to a ninth aspect of the present invention, in the touch panel according to the eighth aspect, the slit has a shape of a straight line, a curved line, a cross, and a cross in which two lines are not orthogonal to each other, substantially perpendicular to the shrinking direction of the upper film substrate. Provided is a touch panel including any of them.

  The invention according to claim 10 is the touch panel according to any one of claims 1 to 7, wherein the upper film substrate and the lower substrate are electrically connected by a conductive adhesive, and the upper film Provided is a touch panel in which a dotted line-like cut is provided between a conductive adhesive portion formed by the conductive adhesive and a touch input region on a substrate.

  The invention according to claim 11 provides the touch panel according to claim 8, wherein the conductive film of the upper film substrate is removed in the vicinity of the inside of the slit.

  The invention according to claim 12 is the touch panel according to claim 11, wherein the conductive film of the upper film substrate is linear in a direction perpendicular to a direction in which the film-side electrode formed on the upper film electrode extends. Provide a touch panel that has been removed.

  According to the present invention, even when the upper film substrate expands due to a change in temperature or humidity, the amount of expansion is properly absorbed, and inappropriate deformation such as undulation is prevented from occurring in the upper film substrate. it can.

  Further, according to the present invention, in the touch panel in which the leader line is not directly connected to the upper film substrate but indirectly connected through the conductive adhesive portion, a slit or dotted line is formed inside the conductive adhesive portion. By forming the notch, breakage / breakage of the film-side electrode due to heat shrinkage of the film can be prevented.

  Further, by removing the conductive film (ITO film) from the upper film substrate inside the slit, it is possible to prevent potential distortion (disturbance of equipotential lines) in the touch input region due to the provision of the slit.

1 is an exploded perspective view showing a schematic configuration of a touch panel according to a first embodiment of the present invention. It is sectional drawing of the touch panel of FIG. It is sectional drawing which shows the state which the upper film board | substrate expanded in the touch panel of FIG. It is a disassembled perspective view which shows schematic structure of the touchscreen which concerns on the 2nd Embodiment of this invention. It is sectional drawing of the touch panel of FIG. It is a disassembled perspective view which shows schematic structure of the touchscreen which concerns on the 3rd Embodiment of this invention. It is the elements on larger scale of the A section of FIG. It is a figure which shows the example of a slit, Comprising: When the slit shape is (a) a straight line, (b) In the case of a curve or an arc, (c) In the case of a cross, and (d) In the case of a cross in which two straight lines are not orthogonal FIG. It is a figure which shows the example which provided the dotted-line notch | incision in the upper film board | substrate instead of the slit. It is a figure which shows the example which removed the ITO film | membrane of the upper film board | substrate partially. It is a figure which shows the XI-XI cross section of FIG. It is a disassembled perspective view which shows schematic structure of the conventional touch panel. It is sectional drawing of the touch panel of FIG. It is sectional drawing which shows the state which the upper film board | substrate expanded and deform | transformed in the touch panel of FIG. It is a disassembled perspective view which shows schematic structure of the conventional touch panel with which the leader line was attached to the lower board | substrate. In the touch panel of FIG. 15, it is a figure which shows the example which a film side electrode breaks by shrinkage | contraction of an upper film board | substrate.

  FIG. 1 is an exploded perspective view showing a schematic configuration of a touch panel 10 according to the first embodiment of the present invention, and FIG. 2 is a cross-sectional view of the touch panel 10 of FIG. The touch panel 10 includes a lower substrate 12 and an upper film substrate 16 that is attached to the lower substrate 12 via a frame-like bonding means 14. The lower substrate 12 and the upper film substrate 16 each have a conductive film surface (not shown) formed by applying a transparent conductive material, and the lower substrate 12 and the upper film substrate 16 face each other. Are pasted together. The lower substrate 12 is a member having a relatively small linear expansion coefficient such as glass, and the upper film substrate is a member having a larger linear expansion coefficient than the lower substrate 12 such as a PET film. As shown in FIG. 1, the entire circumference of the upper film substrate 16 is usually fixed by a frame-like adhesive layer 14.

  As shown in FIGS. 1 and 2, the bonding means 14 includes a frame-shaped foam 18 and a first surface attached to the lower surface or the first surface (that is, the surface facing the lower substrate 12) of the foam 18. And the second adhesive layer 22 attached to the upper surface or the second surface of the foam 18 (that is, the surface facing the upper film substrate 16).

  Here, even if the upper film substrate 16 expands due to a change (rise) in one or both of the temperature and humidity of the atmosphere of the touch panel 10, the foam 18 deforms accordingly, and the upper film substrate 16 is inappropriately deformed. (Waving) and the like are prevented. Specifically, since the foam 18 is interposed between the first adhesive layer 20 and the second adhesive layer 22, even if the upper film substrate 16 expands, both sides of the foam 18 face each other. Since the second adhesive layer 22 is deformed so as to be displaced in the direction, the second adhesive layer 22 is displaced (stretched) in the film extending direction with respect to the first adhesive layer 20. Accordingly, the expansion of the upper film substrate 16 is absorbed, and the upper film substrate 16 does not deform undulating. Therefore, the second adhesive layer 22 preferably has an expansion coefficient equal to or greater than that of the upper film substrate 16.

  The adhesive means formed by sticking the adhesive layer on both surfaces of the foam as described above is, for example, a double-sided adhesive tape in which the foam is a base material and the adhesive tape is attached to both surfaces of the foam. The adhesive tape may be a commercially available one.

  Moreover, as a suitable material which comprises the foam 18, a polyurethane-type material, a polyolefin-type material, and an acrylic foam are mentioned. Moreover, it is preferable that the thickness of a foam is 0.2 mm or more, and it is preferable that it is 0.6 mm or less. The thickness of each of the lower adhesive layer 20 and the upper adhesive layer 22 is preferably 10 μm or more, and preferably 40 μm or less.

The density of the foam 18 is preferably 240 kg / m ³ or more, and preferably 700 kg / m ³ or less. The compression load of the foam 18 is preferably 0.008 MPa or more, and preferably 0.032 MPa or less. Furthermore, the compressive residual strain of the foam 18 is preferably 2% or more, and preferably 4% or less.

  FIG. 4 is an exploded perspective view showing a schematic configuration of the touch panel 30 according to the second embodiment of the present invention, and FIG. 5 is a cross-sectional view of the touch panel 30 of FIG. The second embodiment is different from the first embodiment in that a frame film having a high linear expansion coefficient is used instead of the foam. The touch panel 30 includes a lower substrate 32 and an upper film substrate 36 that is attached to the lower substrate 32 via a frame-shaped bonding means 34. The lower substrate 32 and the upper film substrate 36 each have a conductive film surface (not shown) formed by depositing a transparent conductive material, and the lower substrate 32 and the upper film substrate 36 face each other. Are pasted together. The lower substrate 32 is a member having a relatively small linear expansion coefficient such as glass, and the upper film substrate is a member having a larger linear expansion coefficient than the lower substrate 32 such as a PET film. As shown in FIG. 1, the entire circumference of the upper film substrate 36 is usually fixed by a frame-like adhesive layer 34.

  As shown in FIGS. 4 and 5, the adhesion means 34 is a frame-shaped film material 38 and a third surface affixed to the lower surface or the third surface (that is, the surface facing the lower substrate 32) of the film material 38. Adhesive layer 40 and the upper surface or the fourth surface of the frame-shaped film 38 (that is, the fourth adhesive layer 42 attached to the surface facing the upper film substrate 36. Here, the line of the frame-shaped film 38) The expansion coefficient is equal to or greater than the linear expansion coefficient of the upper film substrate 36, and the frame-shaped film 38 is arranged so that the stretching axis of the frame-shaped film 38 is in the same direction as the stretching axis of the upper film substrate 36.

  Here, when one or both of the temperature and humidity of the atmosphere of the touch panel 30 change (rise), each component of the touch panel 30 expands by an amount based on the respective linear expansion coefficient, but the frame-shaped film 38 is lower. Since the linear expansion coefficient is higher than that of the substrate 32, when the adhesive force of the third adhesive layer 40 that bonds the two is extremely strong, the frame-like film 38 is deformed such as undulation with expansion. However, in the second embodiment, the third adhesive layer 40 is, for example, a double-sided adhesive tape, and the adhesive force of the lower surface of the third adhesive layer 40 (the surface that adheres to the lower substrate 32) is a touch panel such as temperature or humidity. When the environment of 30 changes, the expanded frame-like film 38 is set to such an extent that it can be shifted somewhat in the surface direction in a state of being attached to the lower substrate 32 (that is, without peeling). Therefore, the frame-like film 38 is not deformed such as undulation.

  On the other hand, since the linear expansion coefficient of the frame-shaped film 38 is equal to or greater than the linear expansion coefficient of the upper film substrate 36 as described above, the upper film substrate 36 does not expand more than the frame-shaped film 38. Therefore, as a result, even if the temperature or humidity of the atmosphere of the touch panel is changed, the upper film substrate 36 does not have an inconvenient deformation such as undulation.

  The adhesive force of the fourth adhesive layer 42 that bonds the upper film substrate 36 and the frame-shaped film 38 is not particularly limited, but the linear expansion coefficient of the frame-shaped film 38 is greater than that of the upper film substrate 36. If the coefficient is considerably larger than the coefficient, an excessive tensile force may act on the upper film substrate 36 when both expand, so that the expanded frame-like film 38 also has an expanded frame film 38 with respect to the upper film substrate 36. It is preferably set to such an extent that it can be shifted somewhat in the surface direction.

  Suitable materials for forming the frame-like high linear expansion coefficient film 38 include polycarbonate, polypropylene, and acrylic resin. These materials have a higher coefficient of linear expansion than the polyethylene terephthalate (PET) film often used as the upper film substrate 36.

  In the above embodiment, the bonding means 14 and 34 are configured as a frame (that is, bonded to all four sides of the rectangular film substrate), but only on the two opposite sides or only on the three sides of the upper film substrate. It is good also as a structure to adhere | attach.

  FIG. 6 is a top view of the touch panel 50 according to the third embodiment of the present invention. As with the conventional touch panel 200 shown in FIG. 12, the touch panel 50 has a lead line 52 such as FPC attached to a lower substrate (not shown) such as glass, and has a frame-like double-sided adhesive tape or the like (not shown). ) Is not directly attached to the upper film substrate 54 such as a PET film fixed to the lower substrate. Accordingly, the film-side electrode 56 formed on the upper film substrate 54 is electrically connected to the lower substrate at a conductive adhesive portion 58 (which has a substantially circular shape in the illustrated example) formed of a conductive adhesive.

  Here, in order to prevent the breakage and breakage of the film side electrode due to the heat shrinkage of the upper film substrate as described above, as shown in the partial enlarged view of FIG. A slit 62 is provided in a region outside the touch input region 60 of the upper film substrate 54.

  As shown by the broken line 62 ′ in FIG. 7, the slit 62 is deformed with the thermal contraction of the upper film substrate 54, relieving the inward force generated in the conductive adhesive portion 58, and the film side electrode 56. Is formed into a shape that does not cause breakage or cracks. FIG. 8 shows a specific example. In addition to the right-angled shape shown in FIG. 7, a straight line 62a (FIG. 8 (a)), a curve or arc 62b (FIG. 8 (b)), and a cross Examples include shapes such as 62c (FIG. 8C) and a cross 62d (FIG. 8D) in which the two lines are not perpendicular to each other. The film 58 is configured in such a shape that the film-side electrode 56 is not broken or cracked by reducing the inward force generated in the portion 58 in the plane direction.

  The “slit” in the present invention is not only a cut (that is, substantially not having a width) provided in the upper film substrate, but also a part of the upper film substrate (that is, having a certain width and size). Shall be included.

  By providing a slit inside the conductive adhesive portion in the upper film substrate, it is possible to prevent the film side electrode from being broken at the conductive adhesive portion due to film shrinkage. Therefore, it is not necessary to enlarge the conductive adhesive portion so that it can withstand film shrinkage. Therefore, the frame portion can be narrowed, and a touch panel with a wide operation area can be realized even if the outer dimensions are the same.

  Further, instead of the above-described slit, as shown in FIG. 9, a dotted cut 64 may be provided outside the touch input region 60 of the upper film substrate 54 and inside the conductive adhesive portion 58 in the film surface direction. Even with such a configuration, it is possible to reduce the stress applied to the conductive bonding portion 58 due to film shrinkage. The dotted cut 64 may be formed over the entire length of one side of the upper film substrate 54 as shown in FIG. 9, but may be formed only in the vicinity of the conductive adhesive portion 58.

  When a slit is provided in a part of the upper film substrate as described above, potential distortion (distortion of equipotential line 66) occurs in the vicinity of the slit 62 in the touch input region 60, as shown in FIG. There is a possibility of affecting the touch input operation. Therefore, as shown in FIG. 10, potential distortion can be prevented by forming an ITO removal portion 74 in which the conductive film such as the ITO film of the upper film substrate 54 is partially removed inside the slit 62. The upper film substrate 54 is usually a PET film 68, a hard coat film 70 formed on the upper surface (operation surface) of the PET film 68, and a PET film, as shown in the sectional view 11 along the line XI-XI in FIG. And a conductive film 72 such as an ITO film formed on the lower surface of 68, and the film-side electrode 56 described above is formed on a part of the lower surface of the conductive film 72. Here, as shown in FIGS. 10 and 11, the ITO film 72 is removed in a straight line over one side of the touch input region 60 in a direction perpendicular to the direction in which the equipotential lines 66 ′ extend (the direction in which the film side electrode extends). Thus, by forming the ITO removal portion 74, the influence on the equipotential line by the slit 62 is eliminated. Therefore, as shown in FIG. 10, an equipotential line 66 'without distortion can be secured and a highly accurate touch input (positioning) operation can be performed. The ITO removal portion 74 is preferably provided in the immediate inner side of the slit 62 in order to secure the touch input area 60 as wide as possible.

10, 30, 50, 100, 200 Touch panel 12, 32, 102, 204 Lower substrate 14, 34, 104, 306 Adhesive means 16, 36, 54, 106, 208 Upper film substrate 18 Foam 20, 22, 40, 42 Adhesive layer 38 Frame-like high linear expansion coefficient film 52, 202 Lead line 58, 210 Conductive adhesion part 60 Touch input area 62, 62a, 62b, 62c, 62d Slit 64 Dotted line cut 72 ITO film 74 ITO removal part

Claims (12)

In a touch panel in which an upper film substrate and a lower substrate each provided with a conductive film surface coated with a transparent conductive material are bonded to each other using a frame-like adhesive means so that the conductive film surfaces face each other ,
The adhering means opposes the frame-shaped foam, the first adhesive layer bonded to the first surface facing the lower substrate of the foam, and the upper film substrate of the foam. The touch panel comprised from the 2nd adhesion layer affixed on the 2nd surface.   The touch panel according to claim 1, wherein the adhesive means is a double-sided adhesive tape having a foam as a base material.   The touch panel according to claim 1, wherein the foam is made of a polyurethane material, a polyolefin material, or an acrylic foam.   The thickness of the foam is 0.2 mm or more and 0.6 mm or less, and the thickness of each of the first and second adhesive layers is 10 μm or more and 40 μm or less. The touch panel according to item 1. The foam has a density of 240 kg / m ³ or more and 700 kg / m ³ or less, the compression load of the foam is 0.008 MPa or more and 0.032 MPa or less, and the compression residual strain of the foam is 2% or more. And the touch panel of any one of Claims 1-4 which is 4% or less. In a touch panel in which an upper film substrate and a lower substrate each provided with a conductive film surface coated with a transparent conductive material are bonded to each other using a frame-like adhesive means so that the conductive film surfaces face each other ,
The bonding means includes a frame-shaped film, a third adhesive layer bonded to a third surface facing the lower substrate included in the frame-shaped film, and the upper film substrate included in the frame-shaped film. And a fourth adhesive layer bonded to the fourth surface opposite to
The linear expansion coefficient of the frame-shaped film is equal to or greater than the linear expansion coefficient of the upper film substrate, and the frame-shaped film has the stretching axis of the frame-shaped film in the same direction as the stretching axis of the upper film substrate. The touch panel is arranged as follows.   The touch panel according to claim 6, wherein the adhesive force of the third adhesive layer is set to such an extent that the expanded frame-like film can be shifted in the surface direction in a state of being attached to the lower substrate.   The upper film substrate and the lower substrate are electrically connected by a conductive adhesive, and in the upper film substrate, a slit is provided between a conductive adhesive portion by the conductive adhesive and a touch input region. Item 8. The touch panel according to any one of items 1 to 7.   The touch panel according to claim 8, wherein the shape of the slit includes any of a straight line, a curved line, a cross, and a cross in which two lines are not orthogonal to each other, substantially perpendicular to the contraction direction of the upper film substrate.   The upper film substrate and the lower substrate are electrically connected by a conductive adhesive, and a dotted line cut is provided between the conductive adhesive portion by the conductive adhesive and the touch input area in the upper film substrate. The touch panel according to any one of claims 1 to 7.   The touch panel according to claim 8, wherein the conductive film of the upper film substrate is removed in the vicinity of the inside of the slit.   The touch panel according to claim 11, wherein the conductive film of the upper film substrate is linearly removed in a direction perpendicular to a direction in which a film side electrode formed on the upper film electrode extends.

Images