JP3728736B2 - Touch panel - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a touch panel used for input of a computer or the like, and more particularly to a resistive touch panel.
[0002]
[Prior art]
As shown in an exploded perspective view 5A and a cross-sectional view AA ′ in FIG. 5A, the resistive touch panel 100 is generally formed on one surface of the transparent insulating substrate 102. A fixed electrode 101 in which a transparent conductive layer 103 and a pair of parallel electrode terminals 104 and 104 are formed, and a transparent conductive layer 113 and a pair of parallel electrode terminals 114 and 114 are formed on one surface of a transparent insulating substrate 112. The movable electrode 111 is opposed to each other with a predetermined gap so that the transparent conductive layers 103 and 113 are opposed to each other and the electrode terminals 104 and 114 are orthogonal to each other, and a dot spacer 105 is interposed in the gap. The peripheral edge is bonded with an adhesive layer 106. In the touch panel shown in FIG. 5, a wiring pattern 115 for connection to a control circuit (not shown) is formed on the movable electrode 111 side.
[0003]
This touch panel detects part of the transparent conductive layers 103 and 113 by pressing the surface of the movable electrode 111 to detect the coordinates of the contact points. By applying a predetermined voltage between the electrode terminals 114 and 114 and reading the potential at the contact point with the electrode terminal 104, the X coordinate is applied, and a predetermined voltage is applied between the pair of electrode terminals 104 and 104 and the contact is performed. The Y coordinate is detected by reading the potential at the point with the electrode terminal 114. The dot spacer 105 is made of an insulating resin, prevents contact with the transparent conductive layers 103 and 113 when the pressing force against the movable electrode 110 does not reach a certain level, and prevents the user from unintentionally pressing or insulating base material. Prevents incorrect input due to deformation of
[0004]
Since such a touch panel can detect the absolute coordinates of the pressing (contact) point as described above, for example, on a display screen of an LCD (liquid crystal display) or CRT (CRT) which is a display device such as a computer. It is suitable as an input device that is directly arranged by pressing an area on the touch panel corresponding to a specific area on the display screen.
[0005]
Here, the fixed electrode 101 is formed by forming, for example, an ITO (indium tin oxide) thin film as a transparent conductive layer 103 on a transparent insulating base material 102 such as soda lime glass by a vapor deposition method or a sputtering method. The movable electrode 111 is formed, for example, by forming an ITO thin film as a transparent conductive layer 113 on a flexible transparent insulating substrate 112 such as a PET (polyethylene terephthalate) film by vapor deposition or sputtering. It will be. The electrode terminals 104 and 114 and the wiring pattern 115 are usually formed by screen-printing a silver paste. In some cases, a protective layer made of an insulating resin material is also formed on the pattern made of the silver paste. Here, since the sheet resistance of the electrode terminals 104 and 114 and the wiring pattern 115 needs to be kept sufficiently lower than the sheet resistance of the transparent conductive layers 103 and 113, the film thickness of the transparent conductive layers 103 and 113 is 10 to 10. While it is 50 nm, it is set to about 10 to 30 μm. Since the adhesive layer 106 formed on the peripheral edge portion of the touch panel 100 includes the electrode terminals 104 and 114 and the wiring pattern 115 therein, the thickness thereof is set to 70 μm to 200 μm. Since the height of the dot spacer is usually 5 to 10 μm, the thickness of the entire touch panel is determined by the thickness of the peripheral edge.
[0006]
On the other hand, the touch panel is required to be thin in the usage method as described above, and two types of elastic particles and adhesive particles are realized as thinning while maintaining predetermined input characteristics. A touch panel that includes a spacer and joins upper and lower electrodes in a spot shape with adhesive particles has been proposed (see, for example, Patent Document 1). It has also been proposed that the wiring pattern is formed by sintering using a gold paste having a resistivity lower than that of the silver paste to reduce the film thickness and the pattern width (see, for example, Patent Document 2).
[0007]
[Patent Document 1]
JP-A-7-175575 [Patent Document 2]
Japanese Patent Laid-Open No. 2002-358163
[Problems to be solved by the invention]
However, in the invention as described in Patent Document 1, since the spacer has two types of elastic particles and adhesive particles and the member configuration becomes complicated, or in the invention as described in Patent Document 2, silver is used. Since the gold paste is more expensive than the paste, both of them may lead to an increase in manufacturing cost.
[0009]
In view of the above problems, an object of the present invention is to provide a thin touch panel at low cost.
[0010]
[Means for Solving the Problems]
[00010]
[Means for Solving the Problems]
In order to achieve the above object, in the touch panel according to claim 1, the fixed electrode and the movable electrode face each other via a plurality of dot spacers, and the peripheral portion of the fixed electrode and the peripheral portion of the movable electrode are joined. In the touch panel, the thickness of the display area at the center of the touch panel is configured to be thinner than the thickness of the peripheral edge of the touch panel, and at least some of the plurality of dot spacers are provided on both the fixed electrode and the movable electrode. The fixed electrode and the movable electrode are both flexible, and the peripheral edge of the touch panel has a thickness protruding toward the fixed electrode.
[0011]
The touch panel according to claim 2 is the touch panel according to claim 1, wherein the dot spacers fixed to both the fixed electrode and the movable electrode have a distribution density higher than that of the center of the display area. Are arranged so as to be dense at the periphery of the display area.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an embodiment of a touch panel according to the present invention. In the present embodiment, both the first transparent insulating substrate 12 and the second transparent insulating substrate 7 are made of a flexible transparent resin film such as a PET film, and on one surface of each transparent insulating substrate. The first transparent conductive layer 13 and the second transparent conductive layer 8 each made of an ITO thin film are formed to constitute the fixed electrode 40 and the movable electrode 30, respectively. The electrode terminal 9 and the wiring pattern 11 are formed on the periphery of the movable electrode 30 using, for example, silver paste, and the electrode terminal (not shown) is similarly formed on the fixed electrode 40. In the touch panel 10 according to the present invention, the fixed electrode 40 and the movable electrode 30 are made such that the transparent conductive layers 13 and 8 are opposed to each other, and the peripheral portions thereof are joined by an adhesive layer 6 made of double-sided tape, for example. In addition, dot spacers 4 and 5 are arranged in the gap between the fixed electrode 40 and the movable electrode 30.
[0013]
In the present embodiment, the plurality of dot spacers are composed of the support spacer 4 fixed only to the fixed electrode 40 and the bridging spacer 5 fixed to the movable electrode 30 together with the fixed electrode 40, and arranged in a lattice pattern. Yes. In the touch panel 10 according to the present invention, the gap size between the electrodes 40 and 30 at the peripheral edge B is determined by the thickness of the adhesive layer 6 as in the conventional touch panel, and the both electrodes 40 and The gap dimension between 30 is held at the height by the bridging spacer 5. In the touch panel 10 according to the present invention, the height of the dot spacers 4 and 5 and the thickness of the adhesive layer 6 are such that the thickness h1 of the display area A and the thickness h2 of the peripheral edge B are h1 <as shown in FIG. It is set so as to satisfy the relationship of h2. Here, the display area corresponds to an area that is exposed from the housing of the apparatus and visually recognized by the user on a touch panel mounted on a display device such as an LCD, and matches the operation area that can be operated by pressing. Or it is a part which includes an operation area | region inside.
[0014]
In the present embodiment, both the fixed electrode 40 and the movable electrode 30 are flexible, and the gap size in the display area A is held at a constant value by the bridging spacer 5, so the flatness of the display area A In addition, the thickness of the peripheral edge B can be distributed to the fixed electrode 40 side or the movable electrode 30 side at an arbitrary ratio without affecting the input characteristics of the touch panel 10. In FIG. 1, the thickness h <b> 2 of the peripheral edge B is distributed at an approximately equal ratio between the fixed electrode 40 side and the movable electrode 30 side. However, depending on the mounting conditions of the touch panel 10, a reference example described later (FIG. 2). Thus, the entire fixed electrode 40 is set flat and the thickness of the peripheral portion B is allotted to the movable electrode 30 side (h5 = 0), or conversely, the entire movable electrode 30 is set flat and the thickness of the peripheral portion B is reduced. It is also possible to adopt a configuration (h4 = 0) in which all are distributed to the fixed electrode 40 side.
[0015]
FIG. 2 is a cross-sectional view showing a reference example of the touch panel in the present embodiment. In the touch panel 1 shown in FIG. 2, the first transparent insulating base 2 is made of, for example, soda lime glass, and the first transparent conductive layer 3 made of, for example, an ITO thin film is formed on one surface of the first transparent insulating base 2 to fix the fixed electrode 20. It constitutes. The second transparent insulating substrate 7 is made of, for example, a PET film, and the second transparent conductive layer 8 made of, for example, an ITO thin film is formed on one surface thereof to constitute the movable electrode 30. The electrode terminal 9 and the wiring pattern 11 are formed on the periphery of the movable electrode 30 using, for example, silver paste, and the electrode terminal (not shown) is similarly formed on the fixed electrode 20. The touch panel 1 includes the fixed electrode 20 and the movable electrode 30 which are made to face each other with the transparent conductive layers 3 and 8 facing each other, and the peripheral portions thereof are joined by an adhesive layer 6 made of double-sided tape, for example. In the gap between the electrode 20 and the movable electrode 30, dot spacers 4 and 5 formed of, for example, a thermosetting or photo-curing transparent resin material (acrylic, epoxy, urethane, polyester, etc.) are arranged. ing.
[0016]
The plurality of dot spacers includes a dot spacer (support spacer) 4 fixed only to the fixed electrode 20 and a dot spacer (bridge spacer) 5 fixed to the movable electrode 30 together with the fixed electrode 20. It is arranged in a shape. In the touch panel 1, the gap size between the electrodes 20 and 30 at the peripheral edge B is determined by the thickness of the adhesive layer 6 as in the conventional touch panel, and the gap between the electrodes 20 and 30 in the display area A at the center. The dimensions are held at the height by the bridging spacer 5. At this time, the height of the dot spacers 4, 5 and the thickness of the adhesive layer 6 are the thickness h 1 of the display area A as shown in FIG. And the thickness h2 of the peripheral edge B are set so as to satisfy the relationship of h1 <h2.
[0017]
Here, the distribution mode of the bridging spacer 5 is appropriately set in consideration of the electrical and mechanical characteristics of the touch panels 1 and 10 according to the present invention. For example, the present invention includes an embodiment in which no dot spacer corresponding to the support spacer 4 is present and all dot spacers are the bridging spacers 5. Further, the bridging spacers 5 may be arranged in such a distribution manner that the distribution density is dense at the periphery of the dot spacer arrangement. FIG. 3 is a plan view schematically showing one embodiment of the distribution mode of the above-described bridging spacer 5 by taking the fixed electrode 20 as an example. In the grid-like dot spacer arrangement shown in FIG. 3, the cross-linking spacers 5 indicated by black circles in the drawing have the distribution density closest to the peripheral portion of the arrangement, and gradually decrease toward the central portion. Are arranged so as to have a sparse and constant density. In such a distribution mode, in particular, when the cross-linking spacer 5 is formed under a high temperature condition in the manufacturing process of the touch panel according to the present invention, the transparent insulating substrate 7 made of a flexible insulating film contracts due to cooling after heating. In particular, this is a preferred mode for stably maintaining the thickness of the display region A against the deformation stress. Further, the arrangement of the entire dot spacer is not necessarily limited to the lattice arrangement, and includes a case where distribution is made in any regular or random arrangement.
[0018]
Next, in the touch panel according to the present invention, a process of forming the support spacer and the bridging spacer will be described with a specific example. First, an electrode terminal with a film thickness of 10 μm is formed on a glass substrate on which an ITO thin film is formed by screen printing of silver paste, and then a support spacer is formed by screen printing using an ultraviolet curable epoxy resin. This was used as a fixed electrode. The height of the support spacer was 10 μm and was arranged according to the pattern indicated by the white circles in FIG. At this time, the pitch of the lattice was 1 mm, and the dot diameter of the support spacer was 50 μm. Similarly, an electrode terminal and a wiring pattern having a film thickness of 10 μm were formed on a PET film on which an ITO thin film was formed by screen printing of a silver paste, and this was used as a movable electrode.
[0019]
Next, a cross-linked spacer was screen-printed on the fixed electrode using an ultraviolet curable epoxy resin similar to the material used to form the support spacer (however, no curing treatment was performed at this stage). At that time, the height of the bridging spacer was set to be several μm higher than 10 μm, and the spacers were arranged in a pattern indicated by black circles in FIG. To the movable electrode, a double-sided tape having a thickness of about 100 μm including the adhesive was attached to the peripheral edges of the four sides.
[0020]
Next, the fixed electrode and the movable electrode were attached with the respective conductive layers facing each other. At this time, the display region and the peripheral portion are pressurized by a pressure head having a bottom surface having a convex portion corresponding to the concave portion of the display region A shown in FIG. The crosslinked spacer was cured by ultraviolet irradiation while the spacer and the movable electrode were in contact. Thereby, the bridging spacer was fixed to both the fixed electrode and the movable electrode, and a touch panel as shown in FIG. 2 was obtained.
[0021]
Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the embodiments described herein, and includes various changes and modifications, and the appended claims or techniques thereof. This includes things that do not deviate from the philosophy. For example, in the embodiment described above, the adhesive layer has a flat upper surface, but the adhesive layer in the touch panel according to the present invention is not necessarily limited to this shape. For example, like the adhesive layer 14 shown in FIG. 4, it can also be set as the shape which has the maximum height in the outer peripheral part of a touch panel, and has the gradient which inclines toward the inside. Such a shape is formed by, for example, forming an adhesive layer with a thermosetting adhesive and appropriately adjusting the heating and pressing conditions in the joining process of the electrodes 20 and 30. According to such an adhesive layer 14, it is possible to reduce the curvature of the transparent insulating substrate 7 and reduce the stress due to the deformation in the transition region of the gap dimension from the peripheral portion B to the display region A. It is suitable as an adhesive layer of the touch panel according to the present invention.
[0022]
【The invention's effect】
As described above, according to the present invention, the thickness of the peripheral portion of the touch panel and the member configuration necessary for manufacturing the touch panel are maintained at the same parts as in the past, while the user visually recognizes and operates the parts. Since a certain display area is formed thin, it is possible to achieve a substantial thinning of the touch panel at a low cost.
[0023]
Furthermore, in the touch panel of so-called film / film configuration, the thickness of the peripheral portion can be distributed to the fixed electrode side at an arbitrary ratio, so that the degree of freedom in device design when mounting the touch panel on an LCD or the like increases, and the fixed electrode and Since the movable electrode is joined by the bridging spacer, it is possible to provide a strength-stable touch panel even with a configuration using only a flexible film.
[0024]
Furthermore, according to the invention described in claim 2, a bridging spacer is provided at the peripheral portion of the display region which is a transition portion of the thickness of the touch panel, and thus the movable electrode or the fixed electrode or both of them have a curvature. Since it is densely arranged, it is possible to stably hold the display region against the deformation stress of the insulating base material due to, for example, changes in temperature and humidity.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of a touch panel according to the present invention.
FIG. 2 is a cross-sectional view showing a reference example of a touch panel in the present embodiment.
FIG. 3 is a plan view schematically showing one embodiment of a distribution of bridging spacers in the touch panel according to the present invention.
FIG. 4 is a cross-sectional view showing an example in which an adhesive layer has a gradient in the touch panel according to the present invention.
5A and 5B are diagrams showing a conventional touch panel, in which FIG. 5A is an exploded perspective view, and FIG. 5B is a cross-sectional view taken along line AA ′ in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Touch panel 2 1st transparent insulation base material 3 1st transparent conductive layer 4 Support spacer 5 Bridging spacer 6 Adhesive layer 7 2nd transparent insulation base material 8 2nd transparent conductive layer 9 Electrode terminal 10 Touch panel 20 Fixed electrode ( Glass)
30 Movable electrode 40 Fixed electrode (film)

Claims (2)

In the touch panel in which the fixed electrode and the movable electrode face each other via a plurality of dot spacers, and the peripheral edge of the fixed electrode and the peripheral edge of the movable electrode are joined,
The thickness of the display area in the center of the touch panel is configured to be thinner than the thickness of the peripheral edge of the touch panel,
At least some of the plurality of dot spacers are fixed to both the fixed electrode and the movable electrode,
Both the fixed electrode and the movable electrode have flexibility,
The peripheral part of the said touch panel is provided with the thickness which protrudes in the said fixed electrode side, The touch panel characterized by the above-mentioned.   2. The dot spacers fixed to both the fixed electrode and the movable electrode are arranged so that the distribution density thereof is denser at the periphery of the display area than at the center of the display area. Touch panel as described in 1.

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