JP2001033745A - Production of liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve physical cleaning ability in a device using a substrate on which metal electrodes or active elements are formed, by rubbing the substrate surface where the metal electrodes or active elements are formed with a sponge essentially made from polyvinylalcohol in a substrate cleaning process prior to the process of forming an alignment controlling film. SOLUTION: In any process of cleaning a substrate prior to a process of forming an alignment controlling film, the substrate surface on which metal electrodes or active elements are formed is rubbed with a sponge essentially made from polyvinylalcohol. In this method, a part of the metal electrodes or active elements consists of a film of one or more layers Al or an Al alloy. And, the part of the metal electrodes or active elements consists of the film of one or more layers containing Ag or the Ag alloy. For example, a brushing roller consists of a sponge 51 essentially made from polyvinylalcohol wound around a metal roller 42. By rubbing the substrate 31 with the rotating brushing roller, a physical cleaning effect 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 method for manufacturing a liquid crystal display device used as a display device for OA equipment, audiovisual equipment, portable information equipment and the like.

[0002]

2. Description of the Related Art Conventionally, a color liquid crystal display device which has been mainly used as a display device for OA equipment, audio visual equipment and portable information equipment has a color filter formed on at least one of two substrates. A plurality of transparent electrodes are formed on the other substrate, and a liquid crystal cell having a liquid crystal sandwiched between these two substrates is disposed on the outer surface of the liquid crystal cell almost in parallel with the display electrodes on the substrate surface. It has a configuration in which electronic components for driving the liquid crystal cell are connected through the extended terminal electrodes.

On the other hand, in recent years, it has become necessary to lower the resistance of each electrode in order to enlarge the display screen.
For example, as disclosed in JP-A-09-230806, an electrode made of an Ag-based metal has been proposed. Further, in a reflection type liquid crystal display device which is being widely used as a portable display device, in order to brighten the screen display, a configuration using only one polarizing plate or a configuration using no polarizing plate at all is adopted. A configuration in which a metal electrode serving both as a plate and an electrode is formed on a lower substrate and arranged in a liquid crystal cell has been proposed and put to practical use. As a material of the metal electrode, for example, JP-A-07-134300
As disclosed in Japanese Unexamined Patent Publication (Kokai) No. 08-179252 and Japanese Patent Application Laid-Open No. 08-179252, there have been proposed Al-based and Ag-based materials which are metals having a low resistance value and high reflectivity when used as wiring.

FIG. 5 is a cross-sectional view showing the structure of a liquid crystal cell as a liquid crystal display device. This figure shows the structure of a reflection type color liquid crystal cell having a single polarizing plate in which a display electrode has a reflection function. It is a thing.

Hereinafter, a method for manufacturing the liquid crystal display device will be described. First, a display unit black matrix 4 and an outer peripheral black matrix 6 are provided on a substrate 2 so as to fill a gap between the color filters 3 and a plurality of transparent electrodes 5 are laminated on the surface to form a color filter substrate 21. You. Next, an opposing substrate 22 opposing the color filter substrate 21 is formed of the substrate 2 and a plurality of metal electrodes 8 serving also as a reflector. An orientation control film 7 is formed on each of the counter substrate 22 and the color filter substrate 21,
Spacers 11 for securing a gap between these two substrates are scattered, and after facing them with a seal 9, a liquid crystal 10 is injected therein. Then, the polarizing plate 1 is adhered to the outside of the color filter substrate 21 on the image display surface side, and electronic components for driving the liquid crystal cell are connected to the terminal electrode region A of the counter substrate 22 to complete the liquid crystal display device. I do.

In this manufacturing method, it is indispensable to wash at least both the counter substrate 22 and the color filter substrate 21 before forming the alignment control film. In particular, the opposing substrate 2 on which the metal electrode 8 is formed of an Al-based or Ag-based material used for a reflective color liquid crystal cell.
In the case of cleaning 2, it is necessary to consider that the physical resistance of the metal electrode 8 is weak, that is, its scratch resistance and adhesion to the substrate are weak. It has been found that cleaning for removing adhered foreign substances cannot be performed due to physical effects such as brushing with a nylon brush or a nylon brush.

FIG. 4 is a diagram showing a flow of a general substrate cleaning step in the above case. In FIG. 4, a first step S1 is a step of removing foreign substances adhering to the substrate surface by a chemical cleaning effect using a chemical such as a detergent and a physical cleaning effect obtained by shower pressure and brushing. Next, the second step S2 is a step of replacing the chemical solution in the first step S1 with pure water. In the third step S3, due to the showering pressure of pure water and the physical cleaning effect by brushing, the chemical liquid in the previous step is completely removed, and at the same time, the foreign substances on the substrate surface that cannot be removed in the previous step are removed. In the fourth step S4, the pure water attached to the substrate in the third step S3 is removed by an air knife or a method of spinning the substrate, and then the substrate is dried by heating or the like.

FIG. 3 is a schematic view showing a step of performing washing by showering and brushing employed in the first step S1 and the third step S3 in FIG.

In FIG. 3, a transport roller 32 transports and fixes the substrate 31, and a brushing roller 34, which rotates at the same time that a chemical solution or pure water is supplied from a nozzle 33 onto the substrate 31 by a shower 35, rotates. Rub the surface of. As described above, the substrate 31 is made of A having low physical resistance.
In the case of the counter substrate 22 having the metal electrode 8 formed of an l-based or Ag-based material, the brushing roller 34
Conventionally, as shown in FIG. 2, a cloth made of rayon 41 having a constant thickness with hair raised outward is bonded to a metal roller 42 with an epoxy resin or the like and wound.

[0010]

However, in the above-mentioned conventional method of manufacturing a liquid crystal display device, the density of the hair of the rayon cloth is limited, or the contact area with the substrate or the pressure is increased. Due to the generation of scratches, the entire surface of the substrate cannot be uniformly rubbed without any gap. as a result,
There is a problem that the production yield of the liquid crystal cell is deteriorated due to the adhered foreign matter that cannot be completely removed.

The present invention solves the above-mentioned problems. In a method of manufacturing a liquid crystal display device, a liquid crystal display device using a metal electrode having low physical resistance or a substrate on which an active element is formed is also provided. Reduces foreign matter adhering to the substrate surface without significantly modifying the conventional substrate cleaning process,
An object of the present invention is to provide a method for manufacturing a liquid crystal display device that can improve the production yield of a liquid crystal cell.

[0012]

According to a method of manufacturing a liquid crystal display device of the present invention for solving the above-mentioned problems, a sponge containing polyvinyl alcohol (hereinafter abbreviated as PVA) as a main raw material in a substrate washing step. A physical cleaning effect is obtained by rotating a brushing roller having a structure wound with the substrate and bringing the substrate into contact therewith to brush (rub) the surface of the substrate.

[0013] As described above, the entire surface of the substrate can be rubbed uniformly with no gap and at an unprecedented high pressure without damaging the metal electrode or the active element having low physical resistance. Cleaning performance can be improved.

That is, the invention according to claim 1 is a method of manufacturing a liquid crystal display device in which a plurality of metal electrodes or active elements are formed on at least one of two substrates sandwiching a liquid crystal. In an arbitrary substrate cleaning step before forming an orientation control film, a sponge mainly composed of PVA is used to rub the surface of the substrate on which the metal electrodes or active elements are formed.

[0015] The invention described in claim 2 is the same as the claim 1.
In the above-described method for manufacturing a liquid crystal display device, a part of the metal electrode or the active element is formed of one or more films containing Al or an Al alloy.

[0016] The invention described in claim 3 is the first invention.
In the above-described method for manufacturing a liquid crystal display device, a part of the metal electrode or the active element is formed of one or more films containing Ag or an Ag alloy.

According to the above method, when manufacturing a liquid crystal cell using a substrate on which a metal electrode or an active element is formed in a manufacturing process of a liquid crystal display device, a physical step is performed in a step of cleaning the substrate. The cleaning effect can be improved, and defects due to adhered foreign substances during production of the liquid crystal cell can be reduced.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view showing a brushing roller according to the present embodiment. This brushing roller has a configuration in which a sponge 51 mainly composed of PVA is wound around a metal roller 42. By rubbing the substrate 31 with the rotating brushing roller, a physical cleaning effect can be obtained.

Examples of the sponge mainly composed of PVA include Kanebo Co., Ltd., product name Belle eater, product number E-1.
Can be used. 1 when impregnated with liquid
A brushing roller was prepared by winding the sponge of 0 mm around a metal roller having a diameter of 40 mm.

For comparison, as a conventional brushing roller, the length of the hair foot was 10 mm and the hair thickness was 300 D / 30.
F, a rayon cloth with a hair density of 33000 F / inch ²
A brushing roller wound around a metal roller having the same diameter and a diameter of 40 mm was prepared.

The two types of brushing rollers having the same diameter are installed at 34 in FIG. 3, respectively, and are formed by DC magnetron sputtering according to the flow of the cleaning process shown in FIG. 4 at a roller rotation speed of 2500 rpm. 22
When the substrate on which the Al electrode having a thickness of 00 angstroms was formed was washed, the brushing roller wound with a conventional rayon cloth was so scratched that the electrode was scratched when the amount of hair pressed into the substrate was 0.8 mm. On the other hand, in the brushing roller around which the sponge is wound in the present embodiment, the amount of the sponge pushed into the substrate is 3.5.
Up to mm, the electrode was not abraded.

As a result, with the brushing roller of the present embodiment, it is possible to rub twice the area and evenly with the pressure of four times or more as compared with the conventional brushing roller, and to improve the physical cleaning effect. It was found that it could be dramatically improved.

In the above-described embodiment, the substrate to be cleaned is an example of a substrate on which an Al metal electrode having a reflection function is formed, which is employed in a reflection type liquid crystal display device. Any substrate may be used as long as at least a part of the electrode is formed of a weak Al alloy or an Ag alloy, and may be an electrode substrate constituting a transmission type liquid crystal display device. Further, a substrate on which a thin film active element such as a TFT is formed may be used.

[0025]

As described above, according to the method of manufacturing a liquid crystal display device of the present invention, in an arbitrary substrate cleaning step before forming an alignment control film, a metal electrode is formed using a sponge mainly composed of PVA. Alternatively, by rubbing the surface of the substrate on which the active elements are formed, the physical cleaning effect can be improved without damaging these electrodes or elements. As a result, it is possible to reduce the amount of foreign substances adhering to the substrate surface, and to improve the production yield of the liquid crystal cell.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a brushing roller according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a conventional brushing roller.

FIG. 3 is a schematic diagram showing a general shower and brushing cleaning process.

FIG. 4 is a flowchart showing a general metal electrode substrate cleaning process.

FIG. 5 is a partial cross-sectional view of a general reflective color liquid crystal cell.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Polarizer 2 Substrate 3 Color filter 4 Display part black matrix 5 Transparent electrode 6 Peripheral black matrix 7 Alignment control film 8 Metal electrode 9 Seal 10 Liquid crystal 11 Spacer 21 Color filter substrate 22 Opposite substrate 31 Substrate 32 Transport roller 33 Shower nozzle 34 Brushing roller 41 Rayon cloth 42 Metal roller 51 Sponge made mainly of PVA

Claims (3)

[Claims] 1. A method for manufacturing a liquid crystal display device in which a plurality of metal electrodes or active elements are formed on at least one of two substrates sandwiching a liquid crystal, before forming an alignment control film. In any substrate cleaning process of
A method for manufacturing a liquid crystal display device, characterized by rubbing a surface of a substrate on which the metal electrodes or active elements are formed with a sponge mainly composed of polyvinyl alcohol. 2. The method according to claim 1, wherein a part of the metal electrode or the active element is formed of one or more films containing Al or an Al alloy. 3. The method according to claim 1, wherein a part of the metal electrode or the active element is formed of one or more films containing Ag or an Ag alloy.