JP2008015571A - Method of manufacturing coordinate input panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a coordinate input panel with high accuracy by forming a surface resistor with a thermal decomposition type ITO ink. <P>SOLUTION: The coordinate input panel includes a surface resistor film on a glass substrate, a quadrangular resisting peripheral electrode formed on the surface resistor film to surround the surface resistor film, and lead wires connected from the four vertexes of the resisting peripheral electrode. This method of manufacturing the coordinate input panel is characterized that the surface resistor film is formed of an ITO film by a coating thermal decomposition method. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a coordinate input panel that detects a touch position with a finger or a coordinate indicator.

FIG. 1 and FIG. 2 show an example of a capacitive coupling type coordinate detection device. A coordinate input panel 1 is provided with a resistive peripheral electrode 3 surrounded by a uniform sheet resistor 2, and leads are drawn at the four vertices. 5 is connected to the signal processing unit 6.
In the conventional coordinate input panel, an ITO (indium oxide) film formed by sputtering or a tin oxide film formed by cvd (chemical vapor deposition) is used as the surface resistor 2 on the surface of the glass substrate 4 at about 1 kΩ. / □. Furthermore, a resistive surrounding electrode 3 is formed on the surface resistor 2 so that the resistance value between the apexes is about 100Ω.
As a coordinate detection means of the coordinate input panel, a signal is transmitted from a coordinate indicator (input pen or the like) 8 and the surface resistor 2 receives a signal transmitted from the coordinate indicator 8 through capacitive coupling. A method and a coordinate detection device for driving each part of the surface resistor 2 of which the direction of signal transmission is opposite to this, and receiving the signal by the coordinate indicator 8, or the entire surface resistor 2 is voltage-vibrated, and the coordinate indicator 8 There is a method for detecting the position of a point where a finger (a finger, a conductive material, etc., not shown) comes close to or touches.
Japanese Patent Application No. 2005-289163.

In the above coordinate input panel, in order to accurately detect the position of the point where the input pen, finger, conductor, or the like approaches or contacts, it is necessary to make the potential distribution or current distribution generated on the coordinate input panel uniform. Become.
For this purpose, it is necessary that the surface resistor 2 is uniformly formed and that the resistance value between the four vertices of the resistive surrounding electrode 3 is uniform. At the same time, it is necessary that the resistance value of the resistive surrounding electrode 4 is 20 to 200Ω with respect to the sheet resistance value of 1000Ω / □ of the surface resistor 2.

The coordinate input panel according to the present invention is mainly used on a display device such as a liquid crystal display. However, due to the increase in the area of the liquid crystal display device in recent years, it is essential to increase the area of the coordinate input device. It has become.
Sputtering or cvd (chemical vapor deposition) is used as a conventional film forming method for the surface resistor 2. With these methods, the film thickness near a sheet resistance of 1000 Ω / □ is used. It is difficult to improve the uniformity of the sheet resistance, and the uniformity of the sheet resistance value in a large area is particularly poor.
Moreover, when forming the resistive surrounding electrode 3 mentioned later, a heating process is indispensable, the sheet resistance value of the surface resistor 2 changes at that time, and the sheet resistance value and the resistance value of the resistive surrounding electrode There was a problem that the ratio was shifted.

As a method for forming the resistive surrounding electrode 3, a conductive ink is known. In this ink, carbon powder, silver powder, or the like is used as a conductive material, and the mixing ratio is appropriately adjusted so as to obtain a desired resistance value. With these inks, pattern printing is performed by screen printing or the like, and then heat curing is usually performed at 150 ° C. to 850 ° C.
In another method, the metal resistance film is formed in a desired shape and resistance value by sputtering, plating, or the like.

  The present invention relates to a sheet resistor film on a glass substrate, a square resistor surrounding electrode formed on the sheet resistor film so as to surround the sheet resistor film, and four each of the resistor surrounding electrodes. A coordinate input panel to which a lead line is connected from the apex, wherein the surface resistor film is formed of an ITO film by a coating pyrolysis method is a first gist. The second aspect is a method for manufacturing a coordinate input panel, in which the resistive surrounding electrode is formed by printing and baking a conductive ink, and the conductive ink using glass powder as a binder provides resistance. A third gist of the method for manufacturing a coordinate input panel, which is formed by printing and baking the surrounding electrodes.

  A highly accurate coordinate input panel can be manufactured by forming the surface resistor from the thermal decomposition type ITO ink.

  The ITO film by the coating pyrolysis method used in the present invention is mainly composed of an organic indium compound, and an organic tin compound is added to impart conductivity. Furthermore, in order to provide printability, it is a product obtained by applying and baking a coating solution obtained by dissolving in a solvent and adding a viscosity agent or the like to a glass substrate. As the organic indium compound and the organic tin compound, known compounds are used, for example, indium octylate, indium acetylacetone, and the like, which can be used without any particular limitation. Further, the solvent / viscous agent for forming an ink is not particularly limited, and an arbitrary one can be used.

  Examples of the coating method on the glass substrate include dip coating, spin coating, and screen printing. Each method has a simpler apparatus than the sputtering method and can form a film over a large area. In particular, the screen printing method is advantageous in that it can be applied to a curved surface and the same process as a method for forming a resistive surrounding electrode in a subsequent process can be used.

  The sheet resistance value of the formed surface resistor 2 is determined by the ratio of the organic indium compound and the organic tin compound and the conditions such as the printed film thickness, the firing temperature, and the time, and the conditions for obtaining the desired resistance value are appropriately selected. Just do it. The glass substrate used is not particularly limited in its material, and any material such as soda glass, non-alkali glass, heat-resistant glass, etc. can be used, but the formation temperature of the ITO film by the coating pyrolysis method is usually Since it forms in the range of 300 to 600 degreeC, the soda glass whose heat-resistant temperature is 600 degrees C or less can fully be used.

  As described above, the resistive surrounding electrode is preferably formed by screen printing using conductive ink. As the conductive ink, a resin is used as a binder and heat-cured at 120 to 200 ° C., but it is more preferable to use a conductive ink having glass powder as a binder. In this ink, silver powder or silver-palladium powder is used as a conductive material. However, a temperature higher than the softening temperature of glass powder is required as a heat-curing method after printing, and is usually fired at 450 ° C. to 600 ° C. Is done.

  In the conductive ink using a resin as a binder, since the heat curing temperature is 120 to 200 ° C., there is an advantage that the process is simple. On the other hand, since the binder is a resin, in terms of adhesion and strength, It is inferior to the conductive ink which uses glass powder as a binder, and it is preferable to use the conductive ink which uses glass powder as a binder. In addition, the conductive ink using glass powder as a binder has the advantage that the process equipment can be shared because the heat-curing temperature can be almost the same as that of the thermally decomposable ITO ink.

Hereinafter, the present invention will be described in detail by way of examples with reference to FIGS. 3, 4, and 5.
Soda glass (a glass substrate 4 having a thickness of 3 mm cut to about 430 × 330 mm was prepared. After cleaning the surface, pyrolytic ito ink dx400 manufactured by Sumitomo Metal Mining Co., Ltd. was screen-printed on the entire surface of the glass. The coating was applied and left at room temperature for about 5 minutes, followed by drying at 180 ° C. for 15 minutes, followed by baking at 520 ° C. for 12 minutes to form sheet resistor 2. The obtained sheet resistor. The sheet resistance value and distribution of No. 2 were measured at 48 locations on the glass surface. As a result, it was 965Ω / □ ± 12%.

  Thereafter, the peripheral electrode 3 was printed by screen printing on the surface resistor 2 using a paste obtained by mixing carbon in silver paste ls-504 (resin binder) manufactured by Asahi Chemical Research Co., Ltd. at 180 ° C. Heat cured for 30 minutes. At that time, a pattern in which the pattern width and length were designed so that the resistance value between the four apexes of the peripheral electrode 3 was about 100Ω was used. Since this type of silver conductive ink has low strength and is difficult to solder directly, in order to enable soldering to the four vertices 3-A, 3-B, 3-C, and 3-D, solder only to the four vertices. A soldering terminal 3-E was formed using a copper paste that can be attached (copper paste ACP-051 manufactured by Asahi Chemical Research Co., Ltd.).

  After forming the peripheral electrode 3, the sheet resistance value and distribution of the surface resistor 2 were measured again at 48 locations on the glass surface. As a result, it was 975Ω / □ ± 12%, and a change was seen in the sheet resistance value of the surface resistor 2. There wasn't. Furthermore, the lead wire was soldered to the obtained coordinate input panel, connected to the signal processing unit, and coordinate detection was performed with the input pen. As a result, the accuracy was within 3% and good performance was obtained.

  This will be described with reference to FIG. The glass substrate 4 on which the surface resistor 2 was formed in the same manner as in Example 1 was printed with the surrounding electrode 3 by screen printing using a glass binder-type silver conductive ink (Healeus Co., Ltd. thick film paste C4460). Heat curing at 520 ° C. for 30 minutes. At that time, a pattern in which the pattern width and length were designed so that the resistance value between the four apexes of the peripheral electrode 3 was about 100Ω was used.

  After forming the peripheral electrode 3, the sheet resistance value and distribution of the surface resistor 2 were measured again at 48 locations on the glass surface. As a result, it was 970Ω / □ ± 12%, and a change was seen in the sheet resistance value of the surface resistor 2. There wasn't. Furthermore, as a result of soldering directly to the four vertices of the peripheral electrode 3 on which the lead lines are formed on the obtained coordinate input panel, connecting to the signal processing unit, and performing coordinate detection with the input pen, the accuracy is within 3%. Good performance was obtained.

  In FIG. 5, glass having a curved surface of 2000R was used as the glass substrate 4, and the surface resistor 2 was formed on the convex surface side in the same manner as in Example 1. The sheet resistance value and distribution for forming the obtained sheet resistor 2 were 1100Ω / □ ± 15%. The resistive surrounding electrode 3 was formed in the same manner as in Example 2 except that silver-palladium mixed conductive ink (Heerus Co., Ltd., thick film paste C4026) was used.

After forming the peripheral electrode 3, the sheet resistance value and distribution of the surface resistor 2 were measured again at 48 locations on the glass surface. As a result, it was 1150Ω / □ ± 12%, and there was a change in the sheet resistance value of the surface resistor 2. There wasn't. Furthermore, as a result of soldering directly to the four vertices of the peripheral electrode 3 on which the lead lines are formed on the obtained coordinate input panel, connecting to the signal processing unit, and performing coordinate detection with the input pen, the accuracy is within 3%. Good performance was obtained.
(Comparative Example 1)

  The same operation as in Example 1 was performed except that an ITO film formed by sputtering was used as the surface resistor 2. The sheet resistance value and distribution of the surface resistor 2 were 980Ω / □ ± 20% when the film was attached. Furthermore, after forming the surrounding electrode 3, as a result of the measurement, it was changed to 1950Ω / □ ± 25%.

As a result of performing coordinate detection in the same manner as in Example 1, the coordinate input accuracy was as bad as 8%.
(Comparative Example 2)

  The same operation as in Example 2 was performed except that an ITO film formed by sputtering was used as the surface resistor 2. The sheet resistance value and distribution of the surface resistor 2 were 980Ω / □ ± 20% when the film was attached. Furthermore, after forming the surrounding electrode 3, as a result of the measurement, it was changed to 2900Ω / □ ± 35%.

  As a result of performing coordinate detection in the same manner as in Example 1, the coordinate input accuracy was 20%, which was not practical.

Explanatory diagram of capacitive coupling type coordinate detection device Plane schematic diagram of the coordinate input panel of the present invention Sectional schematic diagram of coordinate input panel of Example 1 and Comparative Example 1 Sectional schematic diagram of coordinate input panel of Example 2 and Comparative Example 2 Sectional schematic diagram of the coordinate input panel of Example 3

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Coordinate input panel 2 Surface resistor 3 Resistive surrounding electrode 4 Glass base material 5 Lead wire 6 Signal processing part 7 Signal processing part 8 Coordinate indicator (input pen)

Claims (3)

A sheet resistor film provided on a glass substrate, a resistor surrounding electrode formed so as to surround the sheet resistor film, and an electrical lead wire connected from the resistor surrounding electrode. A method for manufacturing a coordinate input panel, wherein the surface resistor film is formed of an ITO film by a coating pyrolysis method. 2. The method of manufacturing a coordinate input panel according to claim 1, wherein the resistive surrounding electrode is formed by printing and baking conductive ink. 2. The method for manufacturing a coordinate input panel according to claim 1, wherein the resistive surrounding electrode is formed by printing and baking with a conductive ink using glass powder as a binder.