JP2009093395A - Touch panel and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem where during a thermal shock test for a touch panel set over the surface of a liquid crystal display panel at an interval, the touch panel warps toward the underlying liquid crystal display panel, and the lower surface of the touch panel touches the upper surface of the liquid crystal display panel to cause a nonuniform screen. <P>SOLUTION: A touch panel, in which first and second transparent substrates with transparent conductive films 9 and 10 formed on respective surfaces are opposed to each other via a sealant 6 and the second transparent substrate is set on the screen side of a display device, includes a polarizer 2 on the outer surface of the first transparent substrate and a transmissive surface member 7 that is optically isotropic and has substantially the same or larger thermal shrinkage factor than the polarizer 2 on the outer surface of the second transparent substrate. This prevents the touch panel 1 from touching the surface of the display device even during a thermal shock test. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a touch panel capable of detecting and inputting a position of a pressing portion by pressing the surface, and more particularly, to a touch panel that reduces warpage of the surface with respect to a temperature change and a manufacturing method thereof.

  A touch panel that is attached to the surface of a display device such as a liquid crystal display panel and allows input from the display surface side while viewing a display screen has been put into practical use. FIG. 8A shows a schematic longitudinal sectional view of this type of touch panel 100, and FIG. 8B shows a schematic longitudinal section in a state where the touch panel 100 is attached to the display surface side of the liquid crystal display panel 114. Represents a surface view. In FIG. 8A, the touch panel 100 includes an upper transparent substrate 105 having an upper transparent electrode 107 formed on the surface and a lower transparent substrate 106 having a lower transparent electrode 108 formed on the surface. 109, a λ / 4 phase difference plate 110 is disposed on the outer surface of the lower transparent substrate 106, and the λ / 4 phase difference plate 103, the linearly polarizing plate 102 and the protection are disposed on the outer side of the upper transparent substrate 105. The film 101 is arranged. As the protective film 101, an anti-glare AG (Anti-Glare) film or an anti-reflection AR (Anti-Reflection) film is used.

  A circularly polarizing plate 104 is constituted by the linearly polarizing plate 102 and the λ / 4 retardation plate 103. The circularly polarizing plate 104 is provided to block reflected light reflected from the surfaces of the upper transparent substrate 105, the lower transparent substrate 106, and the upper and lower transparent electrodes 107 and 108 located below the circularly polarizing plate 104. The lowermost λ / 4 retardation plate 110 is provided so that display light incident from below can easily pass through the linearly polarizing plate 102. Electrodes (not shown) are attached to the upper and lower transparent electrodes 107 and 108 formed on the inner surfaces of the upper transparent substrate 105 and the lower transparent substrate 106.

  When the touch panel 100 is pressed with a finger or a pen from the upper protective film 101 side, the upper transparent substrate 105 is deformed downward, and the upper transparent electrode 107 and the lower transparent electrode 108 come into contact with each other. The position is specified by detecting resistance or voltage.

  FIG. 8B is a longitudinal sectional view showing a state in which the touch panel 100 is installed on the liquid crystal display panel 114 via the gap material 115. The liquid crystal display panel 114 has a structure in which a liquid crystal cell 112 is sandwiched between two linearly polarizing plates 111 and 113. A gap between the touch panel 100 and the liquid crystal display panel 114 is defined by the gap material 115. This gap cannot be set too large due to the demand for thinning the display panel member. If the display panel member is too close, the touch panel 100 and the liquid crystal display panel 114 come into contact with each other to generate interference fringes, and the display surface is visually recognized. Worsens sex. Therefore, when the size of the panel surface is 10 to 15 inches, it is usually set to about 1.0 to 1.5 mm.

FIG. 9 shows the relationship between the thermal shock test and the warpage δd of the touch panel 100 toward the liquid crystal display panel. A solid line in FIG. 9A represents a temperature cycle of a thermal shock test performed after the touch panel 100 is attached to the liquid crystal display panel 114. The horizontal axis represents the heat treatment time, and the vertical axis represents temperature and warpage δd of the touch panel toward the liquid crystal display panel in arbitrary units. In the thermal shock test, the upper limit temperature _{TH is set} to 50 ° C. or higher, the lower limit temperature _TL is set to −20 ° C. or lower, and each holding time is set to 30 minutes, for example, and the temperature is changed instantaneously. FIG. 9B shows a change in the warp δd of the touch panel 100 toward the liquid crystal display panel 114 that occurs in the thermal shock test. This warpage δd represents the amount of distortion at the center with respect to the surface in the vicinity of the sealing material 109. The broken lines in FIG. 9A are the results of measuring the warpage δd of the touch panel 100 toward the liquid crystal display panel by taking the sample into the atmosphere at each elapsed time of the thermal shock that is repeatedly performed. This warpage δd increases as the number of thermal shocks increases. When the warp δd reaches a limit value during a predetermined thermal shock test, it comes into contact with the upper surface of the liquid crystal display panel 114, and unevenness such as interference fringes appears and becomes defective.

Patent Document 1 describes that a planar member having a thermal contraction rate equal to that of the polarizing plate or a thermal contraction rate larger than that of the polarizing plate is pasted on the polarizing plate in order to prevent warpage of the surface of the touch panel. ing. This touch panel has a structure in which a lower side member and an upper side member, each having a resistance film made of ITO, are disposed opposite to each other with a dot-like spacer interposed therebetween. And it installs in the surface of a liquid crystal cell by making the lower surface member of a touch panel into the liquid crystal cell side. The upper surface member of the touch panel has a structure in which a planar member made of an optically isotropic film having a resistive film, a λ / 4 phase difference plate, a polarizing plate, and a PET (polyethylene terephthalate) film is laminated in this order. . The planar member attached on the polarizing plate functions to prevent the touch panel from bulging. That is, this planar member has a thermal contraction rate equal to or greater than that of the polarizing plate. By laminating the planar member on the uppermost surface, the upper side member hardly swells relative to the lower side member even after being left at a temperature of about 70 ° C. for a long time as well as in the normal temperature range. That's it.
JP 2001-142638 A

  However, the touch panel described in Patent Document 1 is provided with a planar member for preventing a bulge to prevent a bulge to a side where information is input by a finger or a pen, and a liquid crystal display panel is disposed. It is not intended to prevent warping to the side. Accordingly, in the thermal shock test, it is impossible to prevent the touch panel from being warped toward the liquid crystal display panel and coming into contact with the display surface of the liquid crystal display panel and causing unevenness in the display surface.

In order to solve the above problems, the following measures were taken.
In the first aspect of the present invention, the first and second transparent substrates having a transparent conductive film formed on the surface thereof are disposed to face each other via a sealing material with the transparent conductive film inside. In the touch panel in which the transparent substrate is installed on the display surface side of the display device, a polarizing plate is installed on the outer surface side of the first transparent substrate, and optically on the outer surface side of the second transparent substrate. A translucent surface member that is isotropic and substantially equal to the polarizing plate or has a larger thermal shrinkage than the polarizing plate is provided.

  In the invention which concerns on Claim 2, the said translucent surface member is a film which consists of a triacetyl cellulose, It was set as the touch panel of Claim 1 characterized by the above-mentioned.

  In the invention which concerns on Claim 3, the said polarizing plate has a compressive stress in room temperature, It was set as the touch panel of Claim 1 or Claim 2 characterized by the above-mentioned.

  In the invention which concerns on Claim 4, the 1st and 2nd transparent board | substrate with which the transparent conductive film was formed in the surface is mutually arrange | positioned through the sealing material by making the said transparent conductive film into an inner side, and said 2nd In the manufacturing method of a touch panel used by arranging the transparent substrate on the display surface side of the display device, the step of heat-treating the polarizing plate at a temperature of 50 ° C. or higher, and the heat-treating polarizing plate with the predetermined heat-treated plate And a step of attaching to the outer surface side of the first transparent substrate within a time.

  In the invention which concerns on Claim 5, the process of affixing the translucent surface member which is optically isotropic and has a thermal contraction rate substantially equal to the said polarizing plate on the outer surface side of a said 2nd transparent substrate is included. The touch panel manufacturing method according to claim 4, wherein the touch panel manufacturing method is provided.

  In a touch panel in which a first transparent substrate and a second transparent substrate on which a transparent conductive film is formed are arranged to face each other and the second transparent substrate is installed on the display surface side of the display device, On the surface side, a translucent surface member that is optically isotropic and has a thermal contraction rate substantially equal to or greater than that of the polarizing plate disposed on the outer surface side of the first transparent substrate is disposed. Alternatively, the polarizing plate placed on the outer surface side of the first transparent substrate has a compressive stress at room temperature. Thereby, in the thermal shock test that is repeatedly exposed to high and low temperatures, it is possible to reduce warpage that swells to the display device side of the touch panel, and to reduce interference fringes or color unevenness that occurs between the display surface of the display device and the touch panel. be able to.

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

<First Embodiment>
FIG. 1 is a schematic longitudinal sectional view of a touch panel 1 representing the first embodiment of the present invention. In the touch panel 1, a lower transparent substrate 5 as a second transparent substrate made of glass or the like and an upper transparent substrate 4 as a first transparent substrate made of glass or a resin film form a gap via a sealing material 6. Bonded and fixed. A lower transparent conductive film 10 and an upper transparent conductive film 9 made of ITO (indium tin oxide) are formed on the inner surfaces of the lower transparent substrate 5 and the upper transparent substrate 4, respectively. On the outer surface side below the lower transparent substrate 5, a translucent surface member 7 having optical isotropy is laminated. On the outer surface side above the upper transparent substrate 4, a first λ / 4 phase difference plate 3 and a polarizing plate 2 are laminated to form a circularly polarizing plate 8. In the touch panel 1 shown in FIG. 1, a display device such as a liquid crystal display panel is installed below the lower transparent substrate 5.

  A glass substrate is used as the lower transparent substrate 5. As the upper transparent substrate 4, a glass substrate or a transparent resin film is used. The upper transparent substrate 4 is made thinner than the lower transparent substrate 5 or uses a flexible transparent resin film in order to be easily deformed when pressed from above by a finger or a pen. The lower transparent substrate 5 usually has a thickness of 1.1 mm, whereas when glass is used as the upper transparent substrate 4, the thickness is 0.5 mm or less. For example, a glass substrate of 0.5 to 0.15 mm is used. When a transparent resin film is used, the thickness is reduced to 0.5 mm or less to give elasticity. As the transparent resin film, for example, a polycarbonate film can be used.

  The gap between the upper transparent substrate 4 and the lower transparent substrate 5 is defined by the height of the sealing material 6 and is 100 μm or less, for example, about 10 μm. In order to avoid contact when the upper transparent conductive film 9 and the lower transparent conductive film 10 are not pressed from above, dot-shaped convex portions (not shown) are formed in the gap. The circularly polarizing plate 8 constituted by the first λ / 4 retardation film 3 and the polarizing plate 2 is installed to block the reflected light reflected from the surface of each constituent member. The reflected light reflected from each surface of the upper transparent substrate 4 and the lower transparent substrate 5 and each surface of the upper transparent conductive film 9 and the lower transparent conductive film 10 is blocked to make it easy to see the display image displayed on the display device. Because. The thickness of the first λ / 4 retardation plate 3 is about 60 μm, and the thickness of the polarizing plate 2 is about 200 μm.

  As the translucent surface member 7, for example, a triacetyl cellulose (hereinafter referred to as TAC) film having a thickness of about 80 μm to 120 μm can be used. The TAC film is a material that is optically isotropic and is used for a polarizing plate and the like. The TAC film may be formed as a single layer as the translucent surface member 7 or may be more effective if formed as two layers. can get. The translucent surface member 7 has a thermal contraction rate similar to or higher than that of the polarizing plate 2. Therefore, the touch panel 1 has a structure sandwiched between the translucent surface member 7 and the circularly polarizing plate 8. The translucent surface member 7 and the polarizing plate 2 have the same degree, or the translucent surface member 7 has a larger thermal contraction rate. Therefore, when the touch panel 1 is heated, the convex deformation to the lower side where the display device is installed is alleviated. That is, even if heated, the lower surface of the touch panel is separated from the display surface of the display device. Even if the translucent surface member 7 and the polarizing plate 2 are repeatedly expanded and contracted due to repeated exposure to a high temperature and a low temperature in a thermal shock test, the touch panel 1 is displayed on the display device side. Can be prevented from warping.

  FIG. 2 is a schematic longitudinal sectional view of a touch panel 1 according to another embodiment of the present invention. The difference from FIG. 1 is that a second λ / 4 retardation plate 12 is provided between the lower transparent substrate 5 and the translucent surface member 7 in that the AG film 11 is provided on the upper part of the polarizing plate 2. Is a point. Other configurations are the same as those in FIG. The AG film 11 functions as an antiglare film for preventing the surface of the polarizing plate 2 from being glaringly reflected and making it difficult to see the display. The second λ / 4 retardation plate 12 is provided to change the phase of display light emitted from the liquid crystal display device disposed below by λ / 4 and transmit the circularly polarizing plate 8. The second λ / 4 retardation plate 12 may be installed below the translucent surface member 7. Further, instead of the AG film 11 or together with the AG film, an antireflection AR film may be installed.

  FIG. 3 is a schematic longitudinal sectional view showing a state in which the touch panel 1 according to the embodiment of the present invention is installed on the liquid crystal display panel 17. The same reference numerals are assigned to the same parts or parts having the same function.

  In FIG. 3, a liquid crystal display panel 17 is installed below the touch panel 1 via a spacer 13. The touch panel 1 has a laminated structure of an AG film 11, a polarizing plate 2, a first λ / 4 phase difference plate 3, an upper transparent substrate 4, and a sealing material 6 from below, a lower transparent substrate 5, and a translucent surface member 7. Have The liquid crystal display panel 17 has a laminated structure of a second λ / 4 retardation plate 14, a liquid crystal cell 15, and a polarizing plate 16 from the top. In this example, no polarizing plate is inserted between the touch panel 1 and the liquid crystal cell 15. This is because the polarizing plate 2 of the touch panel 1 also serves as the polarizing plate on the upper side of the liquid crystal display panel 17. The display light transmitted through the liquid crystal cell 15 from below to above has linear polarization. When this display light passes through the second λ / 4 phase difference plate 14 and the first λ / 4 phase difference plate 3, it is returned to the original linearly polarized display light, or the polarization direction is π / 2. It becomes the rotated linearly polarized display light. Thereby, the polarizing plate 2 of the touch panel 1 also serves as the polarizing plate of the liquid crystal display panel 17, and there is an advantage that the thickness and weight can be reduced.

  A gap is formed between the touch panel 1 and the liquid crystal display panel 17. If this gap can be widened, it becomes difficult for the touch panel 1 and the liquid crystal display panel 17 to come into contact with each other. However, thinning is required, and the gap cannot be made too large. Further, when the gap is reduced, there is a problem that the touch panel 1 and the liquid crystal display panel 17 come into contact with each other and display quality is deteriorated. Therefore, this gap is normally set to about 1 mm.

As a result of conducting a thermal shock test on the laminated structure of the touch panel 1 and the liquid crystal display panel 17 shown in FIG. 3, the lower surface of the touch panel 1 and the upper surface of the liquid crystal display panel 17 did not come into contact with each other. The thermal shock test is a test shown in FIG. 9A, wherein the upper limit temperature _TH is 70 ° C., the lower limit temperature _TL is −20 ° C., the holding time is 30 minutes, and the upper limit temperature and lower limit. The temperature of was repeated 250 times.

<Second Embodiment of Touch Panel>
Next, a touch panel 1 according to a second embodiment of the present invention using a heat-treated polarizing plate will be described. 4A is a graph showing a dimensional change when the polarizing plate 2 is heat-treated, and FIG. 4B is a schematic longitudinal sectional view of the touch panel 1 using the heat-treatable compressive polarizing plate 20. FIG. 4C is a schematic longitudinal sectional view showing a state in which the touch panel 1 using the heat-treated compressible polarizing plate 20 is applied to the liquid crystal display panel 17. The same portions or portions having the same function are denoted by the same reference numerals.

  In FIG. 4A, the horizontal axis represents elapsed time, and the vertical axis represents dimensional change of the polarizing plate (both are arbitrary scales). A linear polarizing plate was used as the polarizing plate, and the heat treatment temperature was 70 ° C. The graph of FIG. 4 (a) shows that the polarizing plate is placed in a high temperature bath at a temperature of 70 ° C. and maintained until time T1, then the polarizing plate is taken out into the atmosphere and left until time T2, and then again at a temperature of 70 ° C. It shows the dimensional change of the polarizing plate when it is put in a high temperature bath and maintained until time T3, then taken out into the atmosphere and held until time T4, and then kept in a high temperature bath at a temperature of 70 ° C.

  The polarizing plate is usually formed by laminating polyvinyl alcohol (PVA), which is oriented by impregnating or adsorbing iodine or a dichroic dye, with a TAC film interposed therebetween. This TAC film has heat shrinkability. As shown in FIG. 4A, the polarizing plate shrinks with the passage of time in an atmosphere at a temperature of 70 ° C. due to its heat shrinkability. When the polarizing plate is taken out into the air at room temperature after the elapse of time T1, the polarizing plate gradually expands. The time to stretch is earlier than the time to shrink. A considerable amount of elongation occurs when left in the atmosphere for a long time, but it does not recover to the state before the heat treatment. By further repeating the heat treatment and room temperature, the contraction and the expansion are repeated as shown in FIG.

  In the second embodiment, this property of the polarizing plate 2 is used. Hereinafter, a method for manufacturing the touch panel 1 will be described. First, the upper transparent substrate 4 on which the upper transparent conductive film 9 and an electrode made of silver or the like are formed and the lower transparent substrate 5 on which the lower transparent conductive film 10 and an electrode made of silver or the like are formed are bonded via a sealing material 6. . Next, the first λ / 4 retardation film 3 is attached to the outer surface of the upper transparent substrate 4 using an adhesive or an adhesive. Next, after the polarizing plate 2 is maintained in a high temperature state, it is taken out into the atmosphere, and the first λ is shortened before the heat-shrinkable polarizing plate 2 returns to its original size or before the size does not change. / 4 Affixed on the retardation plate 3 using an adhesive or an adhesive. Then, since the polarizing plate 2 gradually expands, compressive stress is applied to the upper transparent substrate 4 and the lower transparent substrate 5 through the first λ / 4 phase difference plate 3. In order to distinguish the polarizing plate 2 in this state from a normal polarizing plate, it is displayed as a compressive polarizing plate 20. Next, the AG film 11 is attached to the surface of the compressible polarizing plate 20. In addition, 10 hours or less are preferable until it adheres the polarizing plate 2 or the circularly-polarizing plate 8 after heat processing. More preferably, it is applied within 3 hours. This is because the polarizing plate 2 or the circularly polarizing plate 8 contracted by the heat treatment is stretched and the compressibility is not lost.

  In the above manufacturing method, the polarizing plate 2 is maintained at a high temperature of about 70 ° C., and after the amount of shrinkage due to thermal shrinkage is ΔL, the plate is taken out into the atmosphere before the shrinkage amount is restored to ΔL / 2. The polarizing plate 2 was attached to the first λ / 4 retardation plate 3 within a short time.

  FIG. 4B shows a state in which the compressive polarizing plate 20 is pasted on the first λ / 4 phase difference plate 3. The touch panel 1 has a lower transparent substrate 5, a lower transparent conductive film 10 formed on the lower transparent substrate 5, an upper transparent conductive film 9 formed on the inner surface, and a gap provided via a seal material 6. In addition, the transparent substrate 4, the first λ / 4 retardation plate 3, the compressive polarizing plate 20, and the AG film 11 are laminated in this order. The compressible polarizing plate 20 gives compressive stress to other members at room temperature. In addition, air or an inert gas is sealed in the gap between the upper transparent substrate 4 and the lower transparent substrate 5 of the touch panel 1 so as to be a positive pressure with respect to the atmosphere. Since the upper transparent substrate 4 is formed thinner than the lower transparent substrate 5 or is made of a flexible material, stress in a direction in which the upper transparent substrate 4 swells is applied, and the upper transparent conductive film 9 and Interference fringes are unlikely to occur between the lower transparent conductive film 10.

FIG. 4C is a schematic cross-sectional view showing a state in which the compressive polarizing plate 20 is installed on the display surface side of the liquid crystal display panel 17 via the spacer 13. The liquid crystal display panel 17 has a laminated structure of a polarizing plate 16, a liquid crystal cell 15, and a second λ / 4 retardation plate 14 from the bottom. The touch panel 1 has a central portion deformed in a convex shape toward the display viewing side. However, this convex deformation is negligible, and the visibility of the display surface of the lower liquid crystal display panel 17 is not impaired. As a result of performing a thermal shock test by attaching the touch panel 1 to the liquid crystal display panel 17, the lower surface of the touch panel 1 and the upper surface of the liquid crystal display panel 17 did not come into contact with each other. The thermal shock test is a test shown in FIG. 9A, wherein the upper limit temperature _TH is 70 ° C., the lower limit temperature _TL is −20 ° C., the holding time is 30 minutes, and the upper limit temperature and lower limit. The temperature of was repeated 250 times.

  In the second embodiment, the heat-treated polarizing plate 2 is pasted on the first λ / 4 retardation plate 3. Instead of this, the polarizing plate 2 and the first λ / 4 position are attached. The circularly polarizing plate 8 integrally configured with the phase difference plate 3 may be heat-treated, and the polarizing plate 2 and the first λ / 4 phase difference plate 3 may be laminated and bonded to the upper transparent substrate 4 at the same time. Moreover, although the heat processing temperature was 70 degreeC, it is not limited to this. Heat treatment may be performed within the temperature limit allowed for the polarizing plate.

<Third Embodiment of Touch Panel>
FIG. 5A is a schematic longitudinal sectional view showing a third embodiment of the touch panel 1 according to the present invention, and FIG. 5B shows a state in which the touch panel 1 is arranged on the liquid crystal display panel 17. It is a typical longitudinal section showing. In the third embodiment, the touch panel 1 uses both the compressive polarizing plate 20 and the translucent surface member 7. The same portions or portions having the same function are denoted by the same reference numerals.

  As shown in FIG. 5A, the touch panel 1 has a translucent surface member 7 having a thermal contraction rate substantially equal to or larger than that of the polarizing plate from the bottom, and a lower transparent conductive film on the upper surface. A lower transparent substrate 5 on which an upper transparent conductive film 9 is formed, an upper transparent conductive film 9 is formed on the lower surface, and a gap is formed via a sealing material 6, a first λ / 4 phase difference plate 3, and a predetermined The compressive polarizing plate 20 that has been heat-treated at the above temperature and the AG film 11 are laminated.

  The translucent surface member 7 is made of, for example, a TAC film. The compressible polarizing plate 20 has a laminated structure of TAC film, PVA, and TAC film. Therefore, the upper transparent substrate 4 and the lower transparent substrate 5 have a structure sandwiched between TAC films from both sides. Therefore, when the touch panel 1 is heated, the upper and lower surfaces have the same heat shrinkage rate, so that it is possible to reduce the warpage caused by the environmental temperature change. For this reason, even if the ambient temperature changes, the surface of the touch panel 1 is unlikely to warp downward.

  As shown in FIG. 5B, the touch panel 1 is installed on the liquid crystal display panel 17 via the spacer 13. The liquid crystal display panel 17 includes a polarizing plate 16, a liquid crystal cell 15, and a second λ / 4 retardation plate 14 stacked from the bottom. The gap between the translucent surface member 7 of the touch panel 1 and the second λ / 4 retardation plate 14 of the liquid crystal display panel 17 is normally set to about 1 mm. The liquid crystal display panel 17 has no polarizing plate on the upper surface. For this reason, when exposed to a high temperature atmosphere, for example, a temperature of 70 ° C. or higher, the polarizing plate 16 disposed in the lower portion contracts, and a tensile stress acts on the lower surface of the liquid crystal cell 15. Therefore, the central portion of the liquid crystal display panel 17 warps in a convex shape. However, since the touch panel 1 does not easily warp downward, the lowermost surface of the touch panel 1 and the uppermost surface of the liquid crystal display panel 17 do not come into contact with each other.

  Next, the relationship between the shrinkage amount of the circularly polarizing plate and the warpage of the glass plate will be described with reference to FIG. 5, and the effect of reducing the warpage amount of the touch panel 1 in the present invention will be described with reference to FIG.

  FIG. 6A shows the relationship between the amount of shrinkage of the circularly polarizing plate 8 and the heat treatment time. The circularly polarizing plate 8 used is about 13 inches diagonal. The horizontal axis represents the heat treatment time (minutes), and the vertical axis represents the amount of contraction (mm). The amount of shrinkage of the circularly polarizing plate 8 increases in proportion to the heat treatment time. When the heat treatment temperature was 60 ° C., it shrunk by about 0.3 mm in 100 minutes and shrunk by about 0.4 mm in 170 minutes. Moreover, the shrinkage amount increased as the temperature increased. When compared with the heat treatment time of 100 minutes, the shrinkage amount was 0.44 mm when the heat treatment temperature was 70 ° C., and the shrinkage amount was 0.50 mm when the heat treatment temperature was 80 ° C.

  In FIG. 6B, the circularly polarizing plate 8 processed in FIG. 6A is attached to a glass plate having a thickness of 0.2 mm and a diagonal of about 13 inches within a short time, and then 70 The result of having measured the curvature amount of the glass plate immediately after performing the heat processing for 5 degreeC is represented. The horizontal axis represents the time (minutes) when only the circularly polarizing plate 8 was heat-treated before being attached to the glass plate, and the vertical axis was attached to the heat-treated circularly polarizing plate 8 on the glass plate and further heat-treated at 70 ° C. for 5 hours. It represents the amount of warpage (mm) of the glass plate immediately after. The temperature in the figure indicates the temperature during the heat treatment of only the circularly polarizing plate 8. The amount of warpage was measured by placing the glass plate warped in a concave shape on a flat surface plate, measuring the amount of warpage of the outer peripheral portion 12 points, and taking the average value. As shown in FIG. 6 (b), the longer the heat treatment time of only the circularly polarizing plate 8, the more the warp amount of the glass plate due to the subsequent heat treatment at 70 ° C. for 5 hours. Further, the higher the heat treatment temperature of the circularly polarizing plate 8 is, the more the amount of warpage of the glass plate by the subsequent heat treatment is reduced. That is, replacing the glass plate with a touch panel and attaching the circularly polarizing plate 8 after heat treatment to the touch panel means that the amount of warpage of the touch panel is reduced with respect to subsequent heat treatment and thermal shock. In this case, the amount of warpage decreases as the heat treatment time of the circularly polarizing plate 8 is longer and the temperature is higher.

  FIG. 6C shows the correlation between the amount of warpage of the glass plate and the amount of shrinkage of the circularly polarizing plate 8 obtained from the results of FIGS. 6A and 6B. The horizontal axis is the amount of warpage of the glass plate, and the vertical axis is the amount of shrinkage of the circularly polarizing plate 8. That is, as the amount of shrinkage of the circularly polarizing plate 8 increases, the amount of warpage of the glass plate decreases. This correlation coefficient is −0.89, and it can be understood that there is a strong correlation between the shrinkage amount of the circularly polarizing plate 8 and the warpage amount of the glass substrate.

  FIG. 7 is a list showing a comparison result comparing the conventional touch panel and the touch panel 1 according to the present invention. The used sample is a touch panel having a diagonal of about 13 inches, and a circularly polarizing plate 8 is attached to the outer surface of the upper transparent substrate 4. Sample A is a conventional touch panel that uses a glass substrate of company X as the upper transparent substrate 4 and does not use the translucent surface member 7. Sample B is a touch panel in which a glass substrate of company X is used as the upper transparent substrate 4 and one TAC film is attached to the outer surface of the lower transparent substrate 5 as the translucent surface member 7. Sample C is a touch panel in which a glass substrate of company Y is used as the upper transparent substrate 4 and one TAC film is attached to the outer surface of the lower transparent substrate 5. Sample D is a touch panel in which a glass substrate of Y company is used as the upper transparent substrate 4 and two TAC films are laminated and pasted as the translucent surface member 7. Sample E is a conventional touch panel that uses a glass substrate of company Y as the upper transparent substrate 4 and does not use the translucent surface member 7.

  As processing conditions of the circularly polarizing plate 8, No1 is a case where heat treatment is not performed, No2 is a case where the circularly polarizing plate 8 is attached to the outer surface of the upper transparent substrate 4 after heat treatment at a temperature of 60 ° C. for 1 hour, No. 3 is a case where the circularly polarizing plate 8 is attached to the outer surface of the upper transparent substrate 4 after heat treatment at a temperature of 70 ° C. for 1 hour, and No. 4 is an upper transparent substrate 4 after the heat treatment of the circularly polarizing plate 8 at a temperature of 70 ° C. for 3 hours. It is a case where it sticks on the outer surface of. The numbers in the list represent the amount of warpage of the touch panel measured immediately after the samples of each condition were heat treated at 70 ° C. for 5 hours. The amount of warpage of the touch panel was placed on a flat surface plate with the convex surface of the touch panel at the bottom, and the distance from the surface plate surface at the 8 peripheral portions of the touch panel was measured and taken as the average value.

  From the list of FIG. 7, when comparing the sample A without the TAC film and the sample B with one TAC film, the warpage amount was reduced when the TAC film was provided under any condition of the circularly polarizing plate 8. Further, even when the upper transparent substrate 4 uses a glass substrate of company X, the sample TAC film without the TAC film and the sample C with one TAC film have the TAC film in any condition of the circularly polarizing plate 8. The amount of warpage decreased with the provision of. From these results, it can be understood that the amount of warpage of the touch panel can be effectively reduced by installing the translucent surface member 7 having heat shrinkage characteristics on the outer surface of the lower transparent substrate 5.

  In addition, comparing sample C provided with one TAC film and sample D provided with two TAC films, the touch panel warpage is better when two TAC films are provided under any condition of the circularly polarizing plate 8. The amount can be reduced. Moreover, with respect to the conditions of No1 where the circularly polarizing plate 8 is not subjected to heat treatment, No2 to No4 subjected to the heat treatment reduce the amount of warpage of the touch panel. As for the heat treatment conditions, the amount of warpage decreases at a temperature of 60 ° C. for 3 hours rather than 70 ° C. for 1 hour, and further, the amount of warpage decreases at a temperature of 70 ° C. for 3 hours. In particular, when two TAC films are used and the heat treatment temperature of the circularly polarizing plate 8 is 70 ° C. for 3 hours, the amount of warping can be almost eliminated.

  In summary, the amount of warpage of the touch panel is reduced when the TAC film is provided on the outer surface of the lower transparent substrate 5, and the amount of warpage is further reduced when the two TAC films are stacked. In addition, when the circularly polarizing plate 8 is heat-treated at 50 ° C. or higher and pasted on the upper transparent substrate 4 (compressible polarizing plate), the amount of warpage of the touch panel is reduced as compared with a normal case where heat treatment is not performed. .

  In the above description, the liquid crystal display panel 17 has been described as a display device on which the touch panel 1 is installed, but the present invention is not limited to this. Instead of the liquid crystal display panel, a flat panel display panel such as a plasma panel, an EL panel, or the like can be used.

It is a typical longitudinal section showing a touch panel concerning an embodiment of the present invention. It is a typical longitudinal section showing a touch panel concerning an embodiment of the present invention. It is a typical longitudinal section showing the state where the touch panel concerning the embodiment of the present invention was installed in the liquid crystal display panel. It is a typical longitudinal cross-sectional view of the thermal contraction characteristic of a polarizing plate, the touchscreen which concerns on embodiment of this invention, and the liquid crystal display panel which installed this. It is a typical longitudinal cross-sectional view of the touchscreen which concerns on embodiment of this invention, and the liquid crystal display panel which installed this. It is a graph showing the relationship between the shrinkage amount of a circularly-polarizing plate, and the curvature amount of a glass substrate. It is a list showing the comparison result which compared the conventional touch panel and the touch panel concerning the present invention. It is a typical longitudinal cross-sectional view of a conventionally well-known touch panel and the liquid crystal display panel which installed this. It is a longitudinal cross-sectional view of a touch panel warped downward by the thermal shock test and the thermal shock test.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Touch panel 2 Polarizing plate 3, 12, 14 (lambda) / 4 phase difference plate 4 Upper transparent substrate 5 Lower transparent substrate 6 Sealing material 7 Translucent surface member 8 Circular polarizing plate 9 Upper transparent conductive film 10 Transparent conductive film 11 AG film 13 Spacer 15 Liquid crystal cell 16 Polarizing plate 17 Liquid crystal display panel 20 Compressible polarizing plate

Claims (5)

First and second transparent substrates, each having a transparent conductive film formed on the surface thereof, are arranged to face each other via a sealing material with the transparent conductive film inside, and the second transparent substrate is on the display surface side of the display device In the touch panel installed in
A polarizing plate is installed on the outer surface side of the first transparent substrate,
On the outer surface side of the second transparent substrate, a translucent surface member that is optically isotropic and substantially equal to the polarizing plate or has a thermal contraction rate larger than the polarizing plate is provided. A touch panel characterized by that.   The touch panel according to claim 1, wherein the translucent surface member is a film made of triacetylcellulose.   The touch panel according to claim 1, wherein the polarizing plate has a compressive stress at room temperature. A first transparent substrate and a second transparent substrate having a transparent conductive film formed on a surface thereof are disposed to face each other with a sealant with the transparent conductive film inside, and the second transparent substrate is disposed on a display surface of a display device. In the manufacturing method of the touch panel used by arranging on the side,
Heat-treating the polarizing plate at a temperature of 50 ° C. or higher;
Attaching the heat-treated polarizing plate to the outer surface side of the first transparent substrate within a predetermined time after the heat treatment.   5. A step of attaching a translucent surface member that is optically isotropic and has a thermal contraction rate substantially equal to that of the polarizing plate to the outer surface side of the second transparent substrate. The manufacturing method of the touch panel as described in any one of.

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