JP2006011523A - Touch panel sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent reflection due to an electrode in a touch panel sensor for improvement of visibility. <P>SOLUTION: In this touch panel sensor, an insulative transparent base board having transparent conductive films arranged in a predetermined pattern, an insulative reflection preventing layer arranged on the transparent conductive films at least, a transparent adhesive layer, and a transparent surface base board are layered sequentially. In the touch panel sensor, when a refraction index of the insulative reflection preventing layer is represented by r<SB>1</SB>, that of the transparent conductive film is represented by r<SB>2</SB>, and that of the transparent adhesive layer is represented by r<SB>3</SB>, the refraction indexes satisfy the following relation: r<SB>3</SB>< r<SB>1</SB><r<SB>2</SB>. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a touch panel sensor that is disposed on the front surface of a liquid crystal display or the like and functions as an input device.

  A touch panel, which is arranged on the front surface of a display and serves as a display-integrated input device, is widely used because of its ease of use. There are various touch panel systems, and an optical system, an ultrasonic system, a resistive film system, a capacitive coupling system, and the like are known. Among them, the resistive film type is most widely used because of its simple structure, and this resistive type touch panel has a structure in which two transparent conductive films are opposed to each other via a spacer. In this method, the conductive films facing each other are touched and input by pressing with a finger or a pen (for example, see Patent Document 1).

  In addition, the capacitive coupling type touch panel detects the change in the capacitance of a sensor to which a voltage is applied when a human finger or the like approaches the sensor, and inputs it. It is said that the detection position accuracy can be further improved by arranging with a special pattern (see, for example, Patent Document 2). In this capacitive coupling method, compared to the resistive film method, since there is no mechanical working part, it is said that a long-life and highly reliable touch panel can be provided.

Japanese Patent Laid-Open No. 10-48625 JP 2002-326301 A

  In the conventional touch panel, an ITO film is mainly used as a transparent conductive film in any of the methods. However, since the refractive index of the ITO film is relatively high at about 2.0, the reflectance of the sensor part of the touch panel is high. It became high and visibility was bad. Moreover, in the touch panel sensor using the ITO substrate in which the ITO electrode is provided with a pattern, the reflectance is greatly different between the ITO electrode part and the part without the electrode, so that the ITO electrode part and the part without the electrode are clearly reflected. Therefore, there is a problem that the visibility is remarkably inferior.

  Therefore, in Patent Document 1, the reflected light from the ITO film is canceled by using a circularly polarizing plate and a quarter-wave plate. There was a problem of coloring when seen. Further, in Patent Document 2, the reflectance is lowered by providing an antireflection layer on the base of the ITO layer, but the ITO electrode portion is exposed during the process, and defects in the process, the cost of the product, and process management. May become difficult.

  In view of the above, an object of the present invention is to provide a capacitive touch panel that has high visibility and reliability and low manufacturing costs.

In order to solve the above problems, according to the present invention, an insulating transparent substrate in which a transparent conductive film is disposed in a predetermined pattern, an insulating antireflection layer disposed at least on the transparent conductive film, and a transparent adhesive layer , And a transparent surface substrate in order, a refractive index of the insulating antireflection layer is r ₁ , a refractive index of the transparent conductive film is r ₂ , and a refractive index of the transparent adhesive layer is r. _{When 3} , the relationship r ₃ <r ₁ <r ₂ is satisfied.

In the present invention, the refractive index r _{3 of the} pressure-sensitive adhesive layer is smaller than the refractive index r ₂ of the transparent electrode film between the transparent electrode film disposed on the substrate and the pressure-sensitive adhesive layer used for attaching the surface substrate. By providing the antireflection layer having a larger refractive index r ₁ , the reflectance in the transparent electrode film can be lowered and the visibility can be improved.

  Hereinafter, a touch panel sensor of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an example of a touch panel sensor of the present invention. In the touch panel sensor 1 of the present invention, the transparent conductive film 3 is arranged in a predetermined pattern on the main surface of the insulating transparent substrate 2, and the transparent surface substrate 6 is disposed on the transparent conductive film 3 via the transparent adhesive layer 5. The insulating antireflection layer 4 is disposed between the pressure-sensitive adhesive layer 5 and at least the insulating transparent electrode film 3.

  The insulating transparent substrate 2 is not particularly limited, and various plastic materials and glass having transparency can be used. Specific examples of the plastic material include polyethylene terephthalate, polycarbonate, polyethersulfone, polypropylene, polyamide, polyacryl, and cellulose propionate. The insulating transparent substrate 2 preferably has a refractive index of about 1.4 to 1.7, a polyethylene terephthalate having a refractive index of 1.66, or a polycarbonate having a refractive index of 1.55 to 1.59. Is particularly preferred.

  The thickness of the insulating transparent substrate 2 is preferably about 12 μm to 10 cm in consideration of being attached to the display. This is because handling is difficult when the thickness is less than 12 μm, and attachment properties are deteriorated when the thickness is more than 10 cm.

  A transparent conductive film 3 is formed in a predetermined pattern on the main surface of the insulating transparent substrate 2. As this transparent conductive film 3, commonly used metal oxides such as indium tin oxide (ITO), tin antimony oxide, indium oxide, tin oxide, zinc oxide, zinc aluminum oxide, indium zinc oxide, Alternatively, a metal thin film such as gold, silver, copper, or aluminum is used. The transparent conductive film 3 can be formed by a conventional method such as a vacuum deposition method, a sputtering method, an ion plating method, an ion beam method, or a coating method, and has a predetermined pattern by an etching method. Can do.

The thickness of the transparent conductive film 3 is not particularly limited, but is preferably 10 nm or more in order to obtain good conductivity with a surface resistance of 10 ³ Ω / □ or less. On the other hand, if the thickness is too large, the transparency is lowered, and the particularly preferable thickness is about 10 to 300 nm.

An insulating antireflection layer 4 is formed on the transparent conductive film 3. The insulating antireflection layer 4 has a refractive index r _{1 which} is r ₂ which is the refractive index of the transparent conductive film 3, and the refraction of the transparent adhesive layer 5 provided on the insulating antireflection layer 4 which will be described below. When the rate is r ₃ , it is set so as to satisfy the relationship of r ₃ <r ₁ <r ₂ .

  Usually, since the refractive index of the transparent conductive film 3 is about 1.9 to 2.0 and the refractive index of the transparent adhesive layer 5 is usually 1.5 or less, the refractive index of the insulating antireflection layer 4 is It is preferable that it is 1.5-1.9.

Examples of the material of the insulating antireflection layer 4 include Al ₂ O ₃ (refractive index 1.62), Sb ₂ O ₃ (refractive index 1.7), CeF ₃ (refractive index 1.63), MgO (refractive index). 1.75) and the like, and organic materials such as polystyrene, polyester, polyethersulfone, and thiourea polymer, or organic-inorganic hybrid materials can be used. This insulating antireflection layer 4 can be formed by a vacuum deposition method, a sputtering method, an ion plating method, or a coating method, but organic materials, particularly polyester, polystyrene, polyethersulfone, etc., which are soluble in solvents, This method is particularly preferable because a thin film having a good surface property can be formed easily and uniformly in a short time.

  The thickness of the insulating antireflection layer 4 is generally 10 to 1000 nm. If the thickness is less than 10 nm, the surface property is poor, and if it is thicker than 1000 nm, the cost increases. This thickness is more preferably 70 to 110 nm.

  The insulating antireflection layer 4 only needs to be disposed on at least the transparent conductive film 3, but may also be disposed on the insulating transparent substrate 2. That is, in the manufacturing process, when the transparent conductive film 3 is formed on the entire surface of the insulating transparent substrate 2 and the insulating antireflection layer 4 is further formed and then etched, the insulating antireflection layer 4 becomes transparent. However, if the insulating antireflection layer 4 is formed after the transparent conductive film 3 is formed and etched, the insulating antireflection layer 4 is formed not only on the transparent conductive film 3 but also on the transparent substrate 2. Be placed.

  The insulating antireflection layer 4 may be a single layer or a multilayer of two or more layers as long as the above refractive index requirements are satisfied. In the case of a single layer, it is difficult to reduce the reflectance of the sensor part of the touch panel sensor over the entire visible wavelength range, and by reducing the reflectance of the sensor part of the touch panel sensor over the entire visible wavelength range by using multiple layers Can do. However, since the cost increases as the number of layers increases, a single layer is preferable from the viewpoint of cost. In the case of a single layer, the insulating antireflection layer 4 is formed using a material having a refractive index between these in consideration of the refractive indexes of the transparent conductive film 3 and the transparent adhesive layer 5. In the case of multiple layers, it is preferable to laminate two or more low refractive index layers and high refractive index layers alternately from the viewpoint of optical design.

  After the insulating antireflection layer 4 is formed in this way, the transparent surface substrate 6 is pasted through the transparent adhesive layer 5. For this lamination, a transparent adhesive layer 5 may be provided on the transparent surface substrate 6 and may be laminated on the insulating antireflection layer 4, or the transparent adhesive layer 5 may be provided on the insulating antireflection layer 4. It may be provided and the transparent surface substrate 6 may be laminated thereon.

  As the transparent adhesive layer 5, a transparent insulating adhesive known as an adhesive can be used. For example, an acrylic adhesive, a rubber adhesive, a silicone adhesive, an epoxy adhesive or an adhesive Agents.

  As the transparent surface substrate 6, the same material as the insulating transparent substrate 2 can be used, that is, a plastic material such as polyethylene terephthalate, polycarbonate, polyethersulfone, polypropylene, polyamide, polyacryl, cellulose propionate, or glass is used. be able to. The thickness is preferably about 12 μm to 10 cm. If it is less than 12 μm, handling is difficult, and if it is thicker than 10 cm, transparency is lowered. The transparent surface substrate 6 may be subjected to antireflection treatment, antiglare treatment, and fingerprint prevention treatment.

  Although not shown, between the insulating transparent substrate 2 and the transparent conductive film 3, a hard coat layer for improving the surface property and an antireflection layer for further reducing the reflectance of the transparent conductive film 3 are provided. Also good. A melamine resin, urethane resin, alkyd resin, acrylic resin, or the like can be used as the hard coat layer, and silicon dioxide can be used as the antireflection layer. Moreover, you may affix the electromagnetic wave prevention film for removing the noise signal from a back surface on the surface opposite to the surface in which the transparent conductive film 3 was provided of the insulating transparent substrate 2.

  In the present invention, the reflectance from the transparent conductive film 3 can be reduced by disposing the insulating antireflection layer 4 having a predetermined refractive index between the transparent conductive film 3 and the transparent adhesive layer 5. In the capacitive touch panel sensor, the difference in reflectance between the transparent conductive film 3 portion and the portion without the transparent conductive film 3 can be reduced. As a result, it is possible to prevent a decrease in visibility due to reflected light, A highly reliable touch panel with improved appearance can be provided. Moreover, by making the insulating antireflection layer 4 into a multilayer, the reflectance can be lowered in a wide visible wavelength range, and a touch panel having better visibility can be provided.

  The touch panel sensor of the present invention can be manufactured, for example, by the following two methods. In the first method, first, for example, an ITO film as a transparent conductive film is coated on an insulating transparent substrate by sputtering. Next, this ITO film is etched to form an ITO pattern. After the ITO electrode is formed, an insulating antireflection layer is coated, wiring to the controller is performed on the ITO electrode, and finally a transparent surface is formed. A board | substrate is affixed through a transparent adhesive layer. The second method is to coat the insulating antireflection layer before the etching of the ITO film, form a pattern on the ITO film and the insulating antireflection layer, and perform the etching. Is placed only on the ITO electrode, then wiring to the controller is performed on the ITO electrode, and finally the transparent surface substrate is pasted through the transparent adhesive layer.

  When a material capable of solvent coating is used as the insulating antireflection layer, the antireflection effect can be achieved very easily and inexpensively. Providing this anti-reflection layer increases the number of manufacturing steps, but this anti-reflection layer also protects the transparent conductive film during the manufacturing step and also serves to make it difficult to break. Therefore, it is possible to prevent an increase in resistivity due to breakage and deterioration of the transparent conductive film, and to reduce the defect rate of the sensor, and as a result, it is possible to manufacture a product at a low cost.

Example 1
A 1% solution of polystyrene (refractive index: 1.59) manufactured by Wako Pure Chemical Industries, Ltd. was prepared using a mixed solvent of methyl ethyl ketone: toluene = 50: 50 (wt%). This solution was applied onto a PET film having an ITO electrode manufactured by 3M Touch System, using a bar coater. This ITO electrode has a stripe shape as shown in FIG. 2, and the portion of the ITO electrode 8 provided on the PRT film 7 has a width of 4.5 mm, and the portion without the ITO electrode has a width of 0.7 mm. The thickness of the obtained polystyrene layer was 110 nm. A non-reflective PET film with a pressure sensitive adhesive (trade name: Realak 7702UV) made of Japanese fats and oils was pasted thereon to produce a touch panel sensor without wiring to the controller.

Example 2
A touch panel sensor was produced in the same manner as in Example 1 except that a solvent-soluble polyester resin (trade name Byron 28SS, refractive index 1.56) manufactured by Toyobo Co., Ltd. was used instead of polystyrene.

Comparative Example 1
A touch panel sensor was produced in the same manner as in Example 1 except that polystyrene was not applied.

Comparative Example 2
A touch panel sensor was produced in the same manner as in Example 1 except that a PET film without an ITO electrode was used instead of the PET film having an ITO electrode.

Visual test The samples prepared in Example 1, Example 2, and Comparative Example 1 were visually tested. The results are shown in Table 1 below.

  As a result of the visual test, the ITO electrode could not be identified in the example in which the antireflection layer of polystyrene or polyester was provided, but in Comparative Example 1 in which the antireflection layer was not provided, as a result of observing the touch panel sensor from the top surface, The ITO electrode could be identified.

Reflectance measurement The reflectance was measured for the samples prepared in Example 1, Comparative Example 1 and Comparative Example 2. The measuring method measured the reflectance of 500 nm with the spectral reflectometer (MPC-3100, Shimadzu Corporation) of 5 degree and -5 degree. The results are shown in Table 2 below.

  In the sample of Example 1, the reflectance could be lowered as compared with the sample of Comparative Example 1. Thus, the touch panel sensor of the present invention can reduce reflected light. As a result, it is possible to reduce the difference between the reflectance of the portion where the ITO electrode is present and the reflectance from the portion where the ITO electrode is not present, and to provide a touch panel sensor excellent in visibility.

It is a schematic sectional drawing which shows the structure of the touchscreen sensor of this invention. It is a figure which shows the structure of PET film with an ITO electrode used in the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Touch panel sensor 2 ... Insulating transparent substrate 3 ... Transparent conductive film 4 ... Insulating antireflection layer 5 ... Transparent adhesive layer 6 ... Transparent surface substrate 7 ... PET film 8 ... ITO electrode

Claims (3)

An insulating transparent substrate in which a transparent conductive film is arranged in a predetermined pattern;
An insulating antireflection layer disposed on at least the transparent conductive film;
In the touch panel sensor formed by sequentially laminating a transparent adhesive layer and a transparent surface substrate, the refractive index of the insulating antireflection layer is r ₁ , the refractive index of the transparent conductive film is r ₂ , and the refractive index of the transparent adhesive layer is A touch panel sensor characterized by satisfying a relationship of r ₃ <r ₁ <r ₂ when the rate is r ₃ .   The touch panel sensor according to claim 1, wherein the insulating antireflection layer has a refractive index of 1.5 to 1.9.   The touch panel sensor according to claim 1, wherein the antireflection layer is made of an organic material.

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