JP2005216221A - Touch panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a touch panel having reduced light reflection inside the touch panel so as to increase light transmittance from a liquid crystal panel, etc., thereby improving the visibility of a display screen. <P>SOLUTION: The touch panel is structured of two substrates having transparent electrodes on the opposed surfaces with an air layer formed therebetween. On the transparent electrode of at least one substrate, there is provided a low reflection layer that has a refractive index greater than the refractive index of the air layer, and no greater than the refractive index of the transparent electrode, and is formed of such a pattern as to expose the transparent electrode. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a touch panel. The details relate to a touch panel that reduces light reflection inside the touch panel and improves the light transmittance of the display screen.

  2. Description of the Related Art In recent years, touch panels have been frequently used in portable information terminal devices such as mobile phones, PDAs (Personal Digital Assistance), and digital cameras in order to improve operability. There are various types of touch panels such as resistive film type, infrared type, ultrasonic type, electromagnetic induction type, electrostatic capacitance type, and surface acoustic wave type. The price is a resistive touch panel.

  As shown in FIG. 7, the resistive touch panel is composed of an upper panel 10A and a lower panel 10B. A very small spacer 20 is sandwiched between the upper panel 10A and the lower panel 10B, and the upper panel 10A and the lower panel 10B. An upper transparent electrode 13a and a lower transparent electrode 13b made of an ITO (Indium Tin Oxide) resistance film orthogonal to each other are provided on the facing surfaces.

  In the normal state, since the upper transparent electrode 13a and the lower transparent electrode 13b are separated by the spacer 20, electricity does not flow. As shown in FIG. 7, when the upper panel 10A is pressed with a pen tip or the like, The transparent electrode 13a and the lower transparent electrode 13b are brought into contact with each other and energized. At this time, the voltage ratio based on each resistance value generated on the upper transparent electrode 13a and the lower transparent electrode 13b is measured at the contact point. The position is detected.

  FIG. 8 is a diagram exemplifying the structure and operation circuit of a resistive touch panel, in which the voltage dividing ratio in the X direction is measured by the resistive film of the upper transparent electrode 13a and in the Y direction by the resistive film of the lower transparent electrode 13b. When a position on the upper panel 10A, the point A (input point) is pressed, the upper transparent electrode 13a and the lower transparent electrode 13b are brought into contact with each other by the pressure to energize.

  At this time, in the upper transparent electrode 13a, the DC voltages Vx1 and Vx2 corresponding to the resistance values Rx1 and Rx2 generated at the point A (input point) are measured, and in the lower transparent electrode 13b, the point A (input point) is the boundary. The DC voltages Vy1 and Vy2 corresponding to the resistance values Ry1 and Ry2 generated in the above are measured.

  Then, the position of the point A (input point) on the touch panel is detected by the measured voltage ratio Vx1 / Vx2 of the upper transparent electrode 13a (X direction) and the voltage ratio Vy1 / Vy2 of the lower transparent electrode 13b (Y direction). Can do.

  By the way, in a display device combining such a touch panel and a liquid crystal panel (display), members made of various materials are laminated, so that outdoor sunlight or indoor fluorescent light is formed at the interface between the members. There is a problem that the light (incident light) from the lamp is reflected and the visibility of the display screen is deteriorated.

Therefore, between the liquid crystal panel and the touch panel, between the touch panel and the light guide plate of the panel-shaped auxiliary lighting device, between the light guide body of the auxiliary lighting device and the optical film, between the various members laminated on the liquid crystal panel, the member is almost the same. A liquid crystal display device or the like that suppresses reflection by incident light from the outside by filling a substance having an approximate refractive index has been devised (see, for example, Patent Document 1).
JP 2000-275621 A (page 3-4, FIG. 1)

  However, since the resistive touch panel uses a material with a high refractive index for the transparent electrode, outdoor sunlight or light from the indoor fluorescent lamp (incident light) is reflected inside the touch panel, and the visibility of the display screen is reduced. There is a problem of making it worse.

  Specifically, as shown in FIG. 9, the reflected light ra / Sb at the interface Sa / Sb between the gap (hereinafter referred to as air layer) between the upper substrate 11a and the lower substrate 11b and the upper transparent electrode 13a / lower transparent electrode 13b. Since rb and the reflected light r13 at the interface S13a between the upper substrate 11a and the transparent electrode 13a and the lower substrate 11b, the transparent electrode 13b and the interface S13b are large, the visibility of the liquid crystal panel and the like is deteriorated.

  This is because the refractive index of the upper transparent electrode 13a / lower transparent electrode 13b provided on the upper substrate 11a and the lower substrate 11b in FIG. 9 is about 1.8 to 2.0, whereas the upper substrate 11a and the lower substrate 11b. Since the refractive index of the film, plastic, glass, or the like forming the film is about 1.3 to 1.6 and the refractive index of the air layer is 1.0, the upper transparent electrode 13a / the lower transparent electrode 13b and the air The difference in refractive index between the upper transparent electrode 13a / lower transparent electrode 13b and the upper substrate 11a / lower substrate 11b is large, and reflection at the interface Sa / Sb and the interface S13a / S13b between the upper transparent electrode 13a / lower transparent electrode 13b. This is because the rate will increase.

  Therefore, in order to reduce light reflection on the inner surface of the touch panel, by forming one to several layers of a low reflection layer having an intermediate refractive index between the upper and lower substrates and the transparent electrode, The reflection can be reduced and the visibility of the liquid crystal screen or the like at the bottom of the touch panel can be improved.

  For example, as shown in FIG. 10, the low reflective layer 12a / 12b having a refractive index intermediate between the upper substrate 11a and the upper transparent electrode 13a and between the lower substrate 11b and the lower transparent electrode 13b is formed. Thus, the difference in refractive index between the upper substrate 11a and the upper transparent electrode 13a and the lower substrate 11b and the lower transparent electrode 13b is reduced, and the reflection when the low reflection layer is not formed as shown in FIG. Compared with the light r13 (see FIG. 9), the reflected light r23 with respect to the incident light L is suppressed.

  However, as shown in FIG. 11, since the upper transparent electrode 13a and the lower transparent electrode 13b inside the touch panel must be in a conductive state, the upper transparent electrode 13a, the lower transparent electrode 13b, and the air layer There is a problem that the light reflection at the interface cannot be reduced and the visibility of the display screen is not sufficient.

  Therefore, there is a problem to be solved by reducing the light reflection inside the touch panel and improving the visibility of the display screen by improving the light transmittance from the liquid crystal panel or the like.

  In order to solve the above problems, the touch panel according to the present invention is configured as follows.

(1) A touch panel in which an air layer is formed between two substrates provided with transparent electrodes on opposite surfaces, at least on the transparent electrode of the one substrate with a refractive index equal to or higher than the refractive index of the air layer. A touch panel comprising a low reflective layer having a refractive index equal to or lower than the refractive index of the transparent electrode and formed by a pattern exposing the transparent electrode.
(2) The touch panel according to (1), wherein the patterned low reflective layer has an area of the exposed transparent electrode of 50% or less of a total area of the substrate.
(3) The touch panel according to (1), wherein the patterned low reflective layer has a thickness of 1.0 μm or less.
(4) The touch panel according to (1), wherein the patterned low reflective layer has a refractive index in a range of 1.1 to 1.8.
(5) The patterned low-reflection layer is formed on both of the two substrates, and the exposed transparent electrode is formed at the same position. (1) Touch panel.

  Thus, on the transparent electrode of at least one of the substrates, the low refractive index is higher than the refractive index of the air layer and lower than the refractive index of the transparent electrode, and is formed by a pattern that exposes the transparent electrode. By providing the reflective layer, the difference in refractive index between the transparent electrode and the air layer is reduced, and light reflection at the interface with the air layer is reduced.

  The touch panel of the present invention has low refractive index which is patterned so that the transparent electrode is exposed on at least one of the transparent electrodes of the substrate, having a refractive index which is about the middle of the refractive index of the air layer and the transparent electrode. By forming the layer, the difference in refractive index between the transparent electrode and the air layer is reduced, and the light reflection at the interface with the air layer is reduced, so that the light reflection inside the touch panel is suppressed, and the liquid crystal at the bottom of the touch panel The light transmittance from a panel etc. improves and there exists an outstanding effect that the visibility of a screen is improved.

  Next, embodiments of the touch panel according to the present invention will be described with reference to the drawings. However, the drawings are only for explanation, and do not limit the technical scope of the present invention.

  FIG. 1 illustrates the structure of a resistive film type touch panel according to the present invention, which is composed of an upper panel 10A and a lower panel 10B, and an air layer is formed by a spacer 20 sandwiched between the upper panel 10A and the lower panel 10B. Is formed.

  The upper substrate 11a / lower substrate 11b constituting the upper panel 10A and the lower panel 10B include films made of materials such as PET (polyethylene terephthalate), PC (polycarbonate), PVA (polyvinyl alcohol), plastic, glass, and the like. It is used.

  An upper low reflection layer 12a / lower low reflection layer 12b are formed on the upper substrate 11a / lower substrate 11b, respectively, and the surface of the upper low reflection layer 12a / lower low reflection layer 12b is ITO (Indium Tin Oxide) or the like. The upper transparent electrode 13a / the lower transparent electrode 13b are formed by the resistance film, and the upper transparent electrode 13a and the lower transparent electrode 13b are arranged to face each other with the spacer 20 in between.

  A low reflection layer 30 (hereinafter referred to as a patterned low reflection layer 30) formed in a predetermined pattern is provided on the upper layer portion of either or both of the upper transparent electrode 13a and the lower transparent electrode 13b. In FIG. 1, the patterned low reflection layer 30 is formed in the upper layer part of the lower transparent electrode 13b.

  The patterned low reflective layer 30 is an intermediate between the refractive index n1 of the air layer formed by the spacer 20 sandwiched between the upper panel 10A and the lower panel 10B and the refractive index n2 of the upper transparent electrode 13a / lower transparent electrode 13b. Using a material having a refractive index n, for example, a material having a refractive index n of about 1.1 to 1.8, a pattern having a shape that exposes the upper transparent electrode 13a / lower transparent electrode 13b as the lower layer is formed. It is a low reflection layer, and the thickness of the low reflection pattern layer is 1.0 [μm] or less.

  The patterned low reflective layer 30 is formed on both the upper transparent electrode 13a and the lower transparent electrode 13b, or on the upper layer of either one, but when formed on both the upper and lower sides, the upper transparent electrode 13a and The portion where the lower transparent electrode 13b is exposed is aligned. Thereby, even when it is pressed with a pen tip or the like as shown in FIG. 1, the exposed portions of the upper transparent electrode 13a and the lower transparent electrode 13b come into contact with each other in the vertical direction to ensure a conductive state.

  2A is a perspective view when the patterned low-reflection layer 30 is formed on the transparent electrode of the upper or lower substrate, and FIG. 2B is a cross-sectional view of the substrate 11 from the bottom. The layer 12, the transparent electrode 13, and the patterned low reflection layer 30 are formed in this order.

  For example, when the patterned low reflective layer 30 is formed by a circular pattern, as shown in FIG. 3, a circular pattern having a shape that is cut at equal intervals of 1.0 [mm] or less in both the horizontal direction and the vertical direction is formed. Patterning is performed on the transparent electrode 13 by a printing method such as flexographic printing or screen printing or a photolithographic method.

  Note that the shape of the pattern and its size (circle size, etc.) are arbitrary, and the pitch interval of the pattern may be non-uniform. For example, as shown in FIG. 4 (a), it is possible to form a pattern with a circular shape, or as shown in FIG. 4 (b), a pattern with a shape that leaves only a circular portion can be formed. By setting the area of the exposed portion of the transparent electrode 13 to about 50% of the total area (total area of the substrate), preferably 50% or less, the upper transparent electrode 13a and the lower transparent electrode 13b are exposed. A conductive state is ensured in a portion where the light is present, and light reflection is reduced in a portion where the light is not exposed.

  Thus, one or more patterned low-reflection layers 30 having a refractive index n (n1 <n <n2) intermediate between the refractive index n1 of the air layer and the refractive index n2 of the transparent electrode are formed on the transparent electrode 13. Thus, the difference in refractive index between the air layer and the transparent electrode 13 can be reduced, and light reflection at the interface with the air layer can be reduced.

  For example, as shown in FIG. 5A, when the patterned low reflection layer 30 is formed on the upper transparent electrode 13a, the difference in refractive index between the air layer and the upper transparent electrode 13a is reduced, and reflection at the interface Sa is performed. The light ra ′ is reduced. Further, as shown in FIG. 5 (b), by forming patterned low reflective layers 30a / 30b on the upper transparent electrode 13a / lower transparent electrode 13b of the upper panel 10A / lower panel 10B, respectively, The difference in refractive index between the transparent electrode 13a / the lower transparent electrode 13b is reduced, and the reflected light ra '/ rb' at each interface Sa / Sb is reduced.

  In addition, as shown in FIG. 6, the spectral reflection characteristic graph in the patterned low-reflection layer 30 includes the reflectance (two-dot chain line) of the portion where the transparent electrode 13 is exposed (hereinafter, the exposed portion) and the transparent electrode 13. When the reflectance (dotted line) of the part where is not exposed (hereinafter referred to as non-exposed part) is different and the reflectance of the exposed part is not reduced, but when the display screen such as a liquid crystal panel is actually viewed The reflectance of the exposed portion and the reflectance of the non-exposed portion are mixed, and the reflectance is averaged (solid line) and is visually recognized.

  Therefore, by appropriately selecting the ratio of the exposed portion and the non-exposed portion of the transparent electrode according to the pattern when the patterned low reflective layer 30 is formed, at the interface between the air layer and the transparent electrode 13 with respect to incident light. The light reflectance is reduced and the light reflection inside the touch panel is suppressed. Accordingly, the light transmittance of a liquid crystal display or the like under the touch panel is improved, and the visibility of the display screen is improved.

It is explanatory drawing for demonstrating the structure of the touchscreen which concerns on this invention. It is the perspective view and sectional drawing which simplified and showed the structure of the touchscreen which concerns on this invention. It is explanatory drawing for demonstrating the patterned low reflection layer which comprises the touchscreen of this invention. It is explanatory drawing which showed an example of the patterning low reflection layer which comprises the touchscreen of this invention. It is explanatory drawing which showed typically the state of the incident light and reflected light in the touchscreen of this invention. It is the graph which showed the spectral reflection characteristic of the patterned low reflection layer which comprises the touchscreen of this invention. It is explanatory drawing for demonstrating the structure of a resistive touch panel. It is the schematic diagram and circuit diagram for demonstrating the principle of operation of a resistive film type touch panel. It is explanatory drawing which showed typically the state of the incident light and reflected light in the touch panel shown in FIG. It is explanatory drawing for demonstrating the structure of the resistive film type touch panel which has a low reflection layer. It is explanatory drawing which showed typically the state of the incident light and reflected light in the touch panel shown in FIG.

Explanation of symbols

10; Panel 11; Substrate 12; Low reflective layer 13; Transparent electrode 20; Spacer 30; Patterned low reflective layer 10A; Upper panel 11a; Upper substrate 12a; Upper low reflective layer 13a; Lower substrate 12b; lower low reflection layer 13b; lower transparent electrodes 30a, 30b; patterned low reflection layer L; incident light S13; interface Sa, Sb between substrate and transparent electrode; interface r13 with air layer; reflected light r23 at S13 Reflected light ra, rb whose reflectance is reduced by the low reflective layer; reflected light ra ′, rb ′ at the interface with the air layer; reflected light whose reflectance is reduced by the patterned low reflective layer

Claims (5)

A touch panel formed by forming an air layer between two substrates provided with transparent electrodes on opposite surfaces,
Low reflection formed on a transparent electrode of at least one of the substrates by a pattern that has a refractive index that is greater than or equal to the refractive index of the air layer and less than or equal to the refractive index of the transparent electrode and that exposes the transparent electrode. A touch panel characterized by providing a layer. The touch panel as set forth in claim 1, wherein the patterned low reflective layer has an area of the exposed transparent electrode of 50% or less of the total area of the substrate. The touch panel as set forth in claim 1, wherein the patterned low reflective layer has a thickness of 1.0 μm or less. The touch panel as set forth in claim 1, wherein the patterned low reflective layer has a refractive index in a range of 1.1 to 1.8. The touch panel according to claim 1, wherein when the patterned low reflection layer is formed on both of the two substrates, the exposed transparent electrode is formed at the same position.

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