JP2005339394A - Touch panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a touch panel in which there is no generation of a Newton ring, with which adhesive force is maintained and input sensitivity does not lower at the same time. <P>SOLUTION: The touch panel is constituted so that one substrate 1 which has a transparent electrode 8 formed on the inside main surface and formed wiring 910 to be connected to a pair of end parts extending in one direction of the transparent electrode 8, is stuck to the other substrate 2 which has a transparent electrode 5 formed on the inside main surface and formed wiring 6, 7 to be connected to a pair of end parts extending in the other direction perpendicular to one direction, by an adhesive material 4 arranged in the inside periphery of both substrates 1, 2, while allowing to face the transparent electrodes 5, 8 each other. Then, the adhesive material 4 contains particles consisting of plastic, inorganic materials or metal with average particle diameter of 0.04 to 0.15 mm in a principal component consisting of resin. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a touch panel disposed on a flat display panel such as a liquid crystal display panel, an organic EL panel, or a plasma display panel.

  At present, a liquid crystal display device which is a flat display panel is widely used as a light and thin display device for monitors, measuring instruments, industrial machines, portable devices and the like. At the same time, such monitors, measuring instruments, industrial machines, and portable devices are combined with a touch panel that operates by directly touching the screen on the display screen in order to input information for use.

  Actually, such a touch panel is configured separately from the flat display panel. For example, the touch panel is fixed to a frame or a casing for fixing the flat display panel.

  There are several types of touch panels, such as capacitive, optical, and resistive film types, depending on the operation method. Among them, the resistive film type can be easily reduced in thickness, and has a relatively simple structure and low resistance. Because of its price, it is often used for medium and small size input screens of 15 inches or less.

  A conventional resistive film type touch panel will be described with reference to FIGS.

In the figure, 1 is a first transparent substrate and 2 is a second transparent substrate. A transparent electrode 8 made of indium oxide, tin (hereinafter referred to as ITO) or the like is formed on the inner surface side main surface of the first transparent substrate 1 disposed on the lower side. A transparent electrode 5 made of ITO or the like is formed on the inner surface side main surface of the second transparent substrate 2. The first transparent substrate 1 and the second transparent substrate 2 are arranged so that the transparent electrodes 8 and 5 formed on the inner surfaces thereof correspond to each other, and the outer periphery of the first substrate 1 and the second substrate 2 is arranged. It is bonded together by an annular adhesive 4 formed on the part.

  Wirings 9 and 10 are connected to a pair of end portions extending in one direction (vertical direction in FIG. 3) of the transparent electrode 8 formed on the first transparent substrate 1. For example, the wiring 9 extends from the right end in the drawing, and the wiring 10 extends from the left end in the drawing.

  Wirings 6 and 7 are connected to a pair of ends extending in the other direction (left and right direction in FIG. 3) of the transparent electrode 5 formed on the second transparent substrate 2. For example, the wiring 6 extends from the upper end in the drawing, and the wiring 7 extends from the lower end in the drawing.

  A pair of end portions of each transparent electrode 5, 8, that is, an end portion where the wirings 6 to 10 extend is a strip electrode formed of the same material as the wirings 6 to 10 in order to accurately recognize input information. Is formed.

In addition, the wirings 9 and 10 formed on the first transparent substrate 1 and the wirings 6 and 7 formed on the second substrate 2 are formed at different positions in the height direction. It is necessary to transfer the wirings 6 and 7 formed on the second transparent substrate 2 to the substrate side to which a certain flexible printed circuit board 3 is connected, that is, to the first transparent substrate 1 side in FIG. The transition portions 11 and 12 are formed in an internal region surrounded by the adhesive material 4 in the drawing. Thereby, the wiring 6 is connected to the wiring 13 formed on the first substrate 1 via the transition portion 11, and the wiring 7 is connected to the wiring 14 formed on the first substrate 1 via the transition portion 12. ing. Then, the wires 9, 10, 13, 14 are converged and drawn out to the outside by the flexible printed board 3. Note that the wirings 910, 13 and 14 of the FPC 3 and the first substrate 1 are connected by an anisotropic conductive film.
JP-A-9-91091

  In the conventional touch panel, when the gap between the first substrate 1 and the second substrate 2 becomes smaller than a certain value, a ring-shaped interference fringe (Newton ring) is seen. For example, the visibility of a flat display panel arranged at the bottom of the touch panel Will fall. In addition, the appearance of the touch panel itself becomes poor.

  The reason why the Newton ring 18 shown in FIG. 5 is noticeably generated is that the gap between the first substrate 1 and the second substrate 2 becomes smaller than a certain level, and the first substrate 1 and the second substrate 2 as shown in FIG. This is a case where the thickness of the adhesive 4 to which the substrate 2 is bonded is different on the left and right sides, for example.

  The principle of Newton's ring 18 is that a part of the light incident from the front surface of the touch panel is reflected at the interface between the transparent electrode 8 on the first substrate 1 and the internal air layer, and a part of the incident light is second. Is reflected at the interface between the transparent electrode 5 on the substrate 2 and the internal air layer. Due to the nature of both reflected light waves, the light intensity becomes strong when the wave peaks and valleys coincide with each other, and the light intensity becomes weak when the wave peaks and valleys of each wave are opposite. In an area where the gap between the first substrate 1 and the second substrate 2 is relatively small and gradually decreases, the intensity of light is generated while the optical path difference between the two reflected lights changes, and a striped pattern can be seen. Become.

  In order to prevent Newton rings, it is necessary to keep the gap between the first substrate 1 and the second substrate 2 at a certain level or more. As a method for keeping the gap larger than a certain value, it is conceivable to include particles as a gap material in the adhesive 4 surrounding the outer periphery of the touch panel. Conventionally, as disclosed in JP-A-9-91091, there is a technique in which particles are contained in the adhesive material 4, but it can be said that the particle diameter is not large enough to support the panel gap and is relatively small. This conventional example is characterized in that the distance between the substrates is kept constant by beads (spacers) dispersed over the entire touch panel surface. However, when the spacer is interposed between the transparent electrode 5 of the first substrate 1 and the transparent electrode 8 of the second substrate 2, there is a problem that input sensitivity due to touch is lowered.

  The present invention has been devised in view of the above-described problems, and an object of the present invention is to provide a touch panel that does not cause Newton's rings and does not decrease input sensitivity.

  In the present invention, a transparent electrode is formed on the inner surface side main surface, one substrate on which a wiring connected to a pair of ends extending in one direction of the transparent electrode, and a transparent electrode is formed on the inner surface side main surface, The other substrate on which wiring connected to a pair of end portions extending in the other direction orthogonal to the one direction is disposed on the outer periphery of the inner surfaces of both substrates with the transparent electrodes facing each other with a predetermined distance therebetween. In the touch panel formed by bonding with an adhesive, the adhesive contains particles made of plastic, inorganic material, or metal having an average particle diameter of 0.04 to 0.15 mm in a main component made of resin.

  Moreover, the said particle | grain is contained in 5 to 20% of range by volume content rate with respect to the whole volume of the adhesive material after hardening.

  In the touch panel as described above, particles made of a plastic, an inorganic material, or a metal are contained in an adhesive that bonds between the first substrate and the second substrate. In particular, since the average particle diameter of the particles is 0.04 to 0.15 mm, the thickness of the adhesive layer is kept constant at the same level as the particle diameter. At this time, the first substrate is bonded to the second substrate so as to be substantially parallel or parallel to the bulge. The pressing pressure of the substrate when bonding is applied only to the outer periphery adhesive, and the method of not applying the pressing force to the center of the substrate prevents dents in the center of the substrate, If the thickness is maintained at a certain level or more, the distance between the entire surfaces of the transparent substrate is maintained at a certain level or more, and Newton rings can be hardly generated.

At the same time, the region surrounded by the adhesive is not provided with a spacer for controlling the interval, so that the input sensitivity is not lowered.

  Hereinafter, the touch panel of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a plan view of a touch panel according to the present invention, and FIG. 2 is a sectional view thereof. 3 and 4 are denoted by the same reference numerals.

Reference numeral 1 denotes a first substrate, 2 denotes a second substrate, 3 denotes a flexible printed board 3 which is an output cable, and 4 denotes an adhesive.

The first substrate 1 located at the lower part of the touch panel is made of a relatively hard material such as glass or a resin substrate. Since the touch panel is used by being disposed on a flat display panel (not shown), the material of the first substrate 1 is formed of a translucent material. still,
When placed in close contact with the upper surface side of the flat display panel, the first substrate 1 may be a resin film.

  A transparent electrode 8 made of ITO is formed on the inner surface side of the first substrate 1. The transparent electrode 8 is formed in a rectangular shape in the central region of the substrate. In addition, a strip-like electrode connected to the wiring is formed at one end of the transparent electrode 8, for example, at the ends of a pair of sides extending in the vertical direction. For example, the wiring 9 is connected to the belt-like electrode on the right side in FIG. 1, and the wiring 10 is connected to the belt-like electrode on the left side. This electrode is a part of the wiring, and is made of, for example, a low-resistance material such as silver or a silver alloy.

  The second substrate 2 located at the upper portion is made of a material such as a thin glass, a thin resin substrate, or a resin film such as PET (polyethylene terephthalate). Since the touch panel is disposed and used on a flat display panel (not shown), the material of the second substrate 2 is formed of a light-transmitting material.

  A transparent electrode 5 made of ITO is formed on the inner surface side of the second substrate 2. The transparent electrode 5 is formed in a rectangular shape in the central region of the substrate so as to substantially face the transparent electrode 8. In addition, strip electrodes connected to the wirings are formed at the ends of a pair of sides extending in the other direction of the transparent electrode 5, for example, the left-right direction. For example, the wiring 6 is connected to the belt-like electrode on the lower side of FIG. 1, and the wiring 7 is connected to the belt-like electrode on the upper side. This electrode is a part of the wiring, and is made of, for example, a low-resistance material such as silver or a silver alloy.

  Further, the first substrate 1 and the second substrate 2 are bonded together by an annular adhesive 4 so that the transparent electrodes 5 and 8 correspond to each other at the outer peripheral portion of the substrate.

  Further, the wirings 6 and 7 extending from the transparent electrode 5 formed on the second substrate 2 are drilled to the flexible printed circuit board 3 side, and in the middle of the wiring, conductive materials made of silver paste at the electrode transition portions 11 and 12 respectively. Thus, the wirings 13 and 14 formed on the first substrate 1 are connected.

  Then, the wiring 9, the wiring 10, the wiring 13, and the wiring 14 formed on the first substrate 1 are converged, for example, on the left side of the first substrate 1 and are drawn out by the flexible printed circuit board 3. The flexible printed circuit board 3 and the wirings 9, 10, 13, 14 formed on the first substrate 1 are connected by an anisotropic conductive resin 15.

  In such an input area of the touch panel, that is, in an area where the two transparent electrodes 5 and 8 are overlapped with each other, by pressing with a touch pen or a finger from the second substrate 2, the second substrate 2 is bent, The transparent electrode 5 and the transparent electrode 8 are in contact with each other at the pressed portion. And the position pressed for the input can be specified by measuring the current intensity and the resistance value from the wirings 6, 7, 9, 10 respectively.

  A characteristic of the touch panel of the present invention is that the adhesive 4 used for bonding the first substrate 1 and the second substrate 2 is composed mainly of a resin, and the average particle size is 0.04 to 0. .. Particles 19 made of 15 mm plastic, inorganic material or metal were included. In addition, this particle | grain 19 was set to the range of 5-20% by volume content rate with respect to all the solid components (cured adhesive material 4). The adhesive 4 is printed and formed on one substrate, for example, the outer periphery of the first substrate 1 by screen printing, and the second substrate 2 is placed at a predetermined position and pressed to be cured. As for this pressing, it is important to press only the outer peripheral portions of the substrates 1 and 2 with which the adhesive 4 contacts.

The present inventor used Newton due to the difference in the adhesive 4 as the above-mentioned adhesive 4 using a material in which acrylic resin is a main component and particles 19 having an average particle diameter of 0.1 mm made of SiO ₂ are homogeneously kneaded. The occurrence of rings and the adhesion between both substrates were investigated. In the example, the volume content of the particles 19 was set to be 10% of the whole (total volume of the adhesive 4 after curing), and the width of the adhesive 4 was set to 2.0 mm over the entire circumference.

And the sample which did not contain the particle | grains and the sample which changed the average particle diameter of the particle | grains 19 to 0.02-0.17 mm were used, respectively. The results are shown in Table 1.

  As a result, if the average particle size of the particles 19 exceeds a certain value, for example, exceeds 0.15 mm, the area where the substrates 1 and 2 and the adhesive 4 are in close contact with each other is reduced, and the adhesive force is reduced.

On the other hand, if the average particle diameter is less than 0.04 mm, the actual minimum gap between the substrates is less than 0.043 mm, and Newton rings are generated.

  Note that the minimum gap between the substrates is the minimum value obtained by measuring five points in the input surface area of the touch panel (a total of five points in the plane including the four corners and the center). Further, the adhesive force was confirmed by peeling the second substrate 2 in the normal direction of the input screen. Here, a non-defective product which does not cause peeling even with a force of 20 N or more during peeling.

Next, the adhesive strength when the average particle size of the particles 19 was 0.1 mm, the width of the adhesive 4 was 2.0 mm over the entire circumference, and the particle content (volume ratio) was changed was confirmed. In addition, the good product and the defective product were judged when it was peeled off with a force of 20 N as the peeling force.

  When the volume content of the particles 19 is in the range of 5 to 20%, it is 70% or more of the area that contributes to adhesion among the areas where the adhesive 4 is disposed, and is considered good because it does not hinder actual use. When the volume content of the particles exceeds 20%, the adhesive force is reduced, and peeling at the bonded portion of the adhesive 4 becomes remarkable. As a result, the area that contributes to bonding out of the bonding area in which the adhesive 4 is disposed is less than 70% of the total, and it cannot be endured in actual use.

  For this reason, when setting the content rate of the particle | grains 19, it is desirable to set it as 2-20% of volume ratios with respect to the volume of the adhesive material after hardening.

  In the present invention, in the input region, that is, the region where the transparent electrode 8 of the first substrate 1 and the transparent electrode 5 of the second substrate 2 overlap, the spacer for maintaining the inter-substrate gap between the substrates 1 and 2. No members are interposed. For this reason, the transparent electrode 5 and the transparent electrode 8 can contact stably at the time of press input, and input sensitivity and position accuracy can be improved greatly.

It is a top view of the touch panel of the present invention. It is sectional drawing of the dd line in the top view shown in FIG. It is a top view of the conventional touch panel. It is sectional drawing of the aa line in the top view shown in FIG. It is a top view of the conventional touch panel which shows the generation | occurrence | production state of a Newton ring. It is sectional drawing of the bb line in the top view shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... 1st board | substrate 2 ... 2nd board | substrate 3 ... Flexible printed circuit board (FPC)
4 ... Adhesive 5 ... Transparent electrode 8 ... Transparent electrodes 6, 7, 910 ... Wiring 18. Newton ring19. particle

Claims (2)

A transparent electrode is formed on the inner surface side main surface, one substrate on which wiring connected to a pair of ends extending in one direction of the transparent electrode is formed, and a transparent electrode is formed on the inner surface side main surface, and the one direction Affixed to the other substrate on which wiring connected to a pair of ends extending in the other orthogonal direction is attached to each other with an adhesive disposed around the inner surfaces of both substrates with the transparent electrodes facing each other at a predetermined interval. In the touch panel that combines,
The touch panel is characterized in that the adhesive material contains, as a main component made of resin, particles made of plastic, inorganic material, or metal having an average particle size of 0.04 to 0.15 mm. The touch panel according to claim 1, wherein the particles are contained in a volume content of 5 to 20% with respect to the total volume of the adhesive after curing.

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