JPH05114795A - Shielding plate - Google Patents

Abstract

PURPOSE:To provide a shielding plate which is transparent and excellent in shielding effect so as to protect a TFT liquid crystal panel against malfunction caused by noises which are generated in cold cathode ray tube pack light mounted on the TFT liquid crystal panel. CONSTITUTION:A shielding plate is composed of a transparent conductive layer 3 provided to one side of a high molecular film 2, an anti-reflection layer 4 formed on the conductive layer 3, and a lead-out wire connection electrode 5 formed by forming silver paste into an electrode by burning, where contact resistance between the silver paste electrode and a transparent conductive layer is set less than 2kOMEGA/square. An antireflection layer is formed of material soluble in silver paste, whereby contact resistance can be lessened between a conductive layer and silver paste, and thus a shielding plate excellent in transparency and shielding property can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield plate for separating a liquid crystal display section and the like from electromagnetic wave noise generated from peripheral devices, which is more transparent than conventional products and has an electromagnetic wave shielding effect. .

[0002]

2. Description of the Related Art Recently, computers are becoming smaller and lighter. Along with that, a liquid crystal panel has been adopted for the display part. The liquid crystal panel is driven by voltage, and a cold cathode tube is often used as a backlight of the liquid crystal panel. At present, there is a problem that a liquid crystal panel malfunctions due to a potential change generated by a cold cathode tube. Various studies have been conducted on a shield plate capable of eliminating the influence of the potential change without blocking the light from the cold cathode tube. A transparent conductive film having no antireflection layer and an electrode for connecting a lead wire has a good shielding effect, but only a film having inferior transparency is obtained as compared with one having an antireflection film. Further, a conventional inorganic thin film such as magnesium fluoride using an antireflection film has a drawback that the contact resistance between the conductive layer and the lead-line connecting electrode is large and a sufficient shield effect cannot be obtained.

[0003]

DISCLOSURE OF THE INVENTION The present invention has been made as a result of various studies in order to solve the problem that the liquid crystal display unit malfunctions due to a potential change generated from a cold cathode tube or the like. Is to provide a shield plate having excellent transparency and shielding properties.

[0004]

According to the present invention, a polymer film (2) has a transparent conductive layer (3) on at least one side thereof, and an antireflection layer (4) is provided on the conductive layer, and then leads are connected. A shield plate having an electrode formed by firing a silver paste as a working electrode (5) and having a contact resistance value between the silver paste electrode and the transparent conductive layer of 2 kΩ / □ or less.

As for the contact resistance value (Rt) here, as shown in FIG. 2, the shield plate is a rectangle having a vertical length of a cm and a horizontal length of b + 2 cm. When the electrode tube resistance is Rm and the sheet resistance value of the conductive layer is Rf, Rt = b / a × Rm-Rf.

As the polymer film used in the present invention, a transparent polymer film having heat resistance is used for forming a conductive film by vacuum deposition, ion plating, sputtering or the like. Polysulfone, polyether sulfone, polyethylene Examples include polyester resins such as terephthalate.

As the metal and / or metal oxide which is the material of the conductive film, gold, silver, zirconium, indium, tin, titanium or the like or tin oxide, indium oxide, tin-
Cadmium oxide or the like can be used.

Naturally, the conductive film may be applied to the polymer film by applying the conductive film by physical deposition such as vacuum deposition method, sputtering method or chemical deposition method such as chemical plating method or vapor phase method. It doesn't matter. In addition, even if a third layer is formed between the polymer film and the conductive layer in order to improve the adhesion and the like of applying these conductive films to the polymer film, there is no problem. Rather, increasing the adhesion between the polymer film and the conductive film layer is desirable in order to improve the flexibility and workability of the shield plate made of the transparent conductive film.

A polymer film (2) provided with a transparent conductive film (3), and a polymer resin is top-coated on the conductive film (3) to provide an antireflection film layer (4). If the refractive index of the top coat layer of this polymer resin is 1.7 or less, an antireflection effect is exhibited, but if it is 1.6 or less, it is more preferable that almost no reflected light is generated. Further, it is important that the polymer resin is soluble in the silver paste and is formed of a polymer having an excellent film forming property. Examples of polymers satisfying such conditions include soluble polycarbonate, PMMA, cyanoethylated hydroxyethyl cellulose, cyanoethyl pullulan, cyanoethylated poval and the like.

As a thin film forming method, a coating method using a solution is generally used, and a dipping method, a roll coater method,
Conventional methods such as doctor blade method and spinner method are used. After coating, it is dried and, if necessary, cured to obtain a transparent conductive film (1).

The transparent conductive film (1) thus obtained serves as a shield plate to which the lead-line connecting electrode (5) is applied by silver paste printing. FIG. 1 shows a front view of the shield plate. A silver paste is screen-printed on the lead wire connecting electrode part (5) in FIG. 1 and baked at 100 to 180 ° for 10 to 120 minutes. The conductive substance in the silver paste diffuses into the antireflection film layer during firing, and the connection resistance value between the lead wire connection electrode and the conductive layer is low, and a good shielding effect can be obtained by connecting the ground wire to the electrode. When the contact resistance value is 2 kΩ / □ or more, the shielding effect cannot be obtained regardless of the sheet resistance value of the conductive layer.

[0012]

EXAMPLES Example 1 A 100 μm thick PES film (2) was coated with an ultraviolet-cured material containing epoxy acrylate and urethane acrylate as main components as an undercoating agent, and the thickness was 30 nm by a sputtering method. An ITO thin film layer (3) having a surface sheet resistance value of 300Ω / □ was formed. Onto this ITO film, cyanoethylated hydroxycellulose 5 parts by weight cyanoethylated pullulan 5 parts by weight Leveling agent; Florard FC-431 (manufactured by Sumitomo 3M) 0.05 parts by weight dimethylformamide 990 parts by weight A coating agent having a film thickness of 200 nm Was coated with a kiss coater and heated at 120 ° C. for 3 minutes to scatter the solvent component to form an antireflection film layer (4). The sheet resistance value of the obtained transparent conductive film was 350 Ω / □, and the total light transmittance of visible light was 90%. A silver paste (manufactured by Shinto Chemitron, Syntron K-343) was applied to the transparent conductive film (1) using a screen printing plate.
Apply 1) to a length of 10 cm with a width of 1 cm and an interval of 20 cm.
After firing at ℃ for about 1 hour, as shown in Figure 1, length 10 cm,
A blank was punched out to a width of 30 cm, and an electrode (5) for connecting a lead wire was provided to prepare a shield plate. After that, a lead wire is attached to the lead wire connecting electrode (5) by soldering, the lead wire is mounted between the TFT liquid crystal cell and the cold cathode tube, and then the lead wire is connected to the ground electrode of the cold cathode tube and driven. No malfunction due to potential distribution was observed. Then Fig. 2
Drawer wire connection electrode width (c) 1 cm, length (a) 10
As a result of cutting out a shield plate measuring piece of 20 cm in width and 20 cm in width (b) and measuring with a tester, the contact resistance value was 10 Ω / □.

(Comparative Example 1) The shield plate obtained by changing the method of applying magnesium fluoride only to the antireflection film in Example 1 had a total light transmittance of 90% or more, but the contact resistance value was 10 kΩ /. It was as high as □, and the effect of preventing malfunction of the TFT was not obtained. (Comparative Example 2) When the antireflection film in Example 1 was omitted, the contact resistance value was as good as 5 Ω / □, but the total light transmittance of the transparent portion of the shield plate was as low as 84% and the liquid crystal panel display section was low. As a result, the visibility during driving was reduced.

[0014]

The shield plate used for the TFT liquid crystal panel is required to be highly transparent and have a good shield effect. The shield plate obtained by the present invention has high transparency and high shieldability, which have been difficult to achieve at the same time, and is suitable for the use.

[Brief description of drawings]

FIG. 1 is a front view and an AA ′ cross-sectional view of a shield plate of the present invention.

FIG. 2 is a front view of a measuring piece for measuring a contact resistance value of a shield plate.

Claims (1)

[Claims] 1. A polymer film having a transparent conductive layer on at least one side, and an electrode formed by firing a silver paste for connecting a lead line after applying an antireflection film on the conductive layer, A shield plate having a contact resistance value of 2 kΩ / □ or less between a silver paste electrode and a transparent conductive layer.