JPS61130922A - Manufacture of liquid crystal display panel - Google Patents

Abstract

PURPOSE:To prevent the generation of an irregular pattern, and to improve the hue and color tint with uniform lightness over the whole surface, by immersing a plate which has formed an oriented film on an insulating substrate, into a warm bath. CONSTITUTION:A plate which has formed an ITO layer 2 and an oriented film 6 in a parallel line shape on a glass substrate 1 is immersed in a warm bath 3 of about 90 deg.C for 30 minutes, and the surface layer of the film 6 is softened. Subsequently, many thin grooves are formed in the same direction on the surface layer of the oriented film 6 by rubbing. Two pieces of substrates 1 re opposed and stuck through a spacer 4 in the direction where the ITO electrodes 2 of a parallel line shape are orthogonal to each other, and its gap is sealed with a liquid crystal 5. Accordingly, the generation of an irregular pattern is decreased remarkably, the lightness becomes uniform on the whole surface, and excellent hue and color taste can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a liquid crystal display panel. especially,
Improves the alignment of liquid crystals, makes the displayed image uniform, and
This invention relates to an improvement in an alignment treatment process that improves its brightness and hue.

[Prior Art] A liquid crystal display panel is a display device that changes the alignment direction of liquid crystals between a voltage applied state and a voltage non-applied state, thereby greatly changing the reflectance and transmittance of light of a specific wavelength. Therefore, the alignment direction of the liquid crystal is perfect in the voltage applied state and in the non-voltage applied state.

In addition, it is necessary to change uniformly over the entire picture frame. In order to make this possible, an alignment treatment step has conventionally been performed in the manufacturing method of a liquid crystal display panel. Otherwise, the alignment direction of the liquid crystal will be difficult to be uniform, resulting in poor 0NeOFF ratio, low brightness, and poor hue and tint.

The alignment process in the conventional technology involves forming display electrodes or counter electrodes on an insulating substrate such as a glass plate, and then applying a resin such as polyvinyl alcohol or polyvinyl phenol to a thickness of several hundred coats.

After curing this, a rubbing machine or the like is used to form narrow grooves in the same direction in the resin film, each having a depth of about several dozen.

[Problem that the invention seeks to solve]

With the alignment treatment method according to the conventional technology, the alignment of all the liquid crystals is not necessarily aligned in the same direction, and therefore, when the ON
- It has the disadvantages of low OFF ratio, low brightness, and unsatisfactory hue and tint. In particular, there is a fatal drawback that regions with particularly poor orientation tend to remain locally on the picture frame surface, and irregular patterns are generated in these regions, making the screen non-uniform.

In order to improve the alignment of a liquid crystal display panel, the cell thickness (
It is effective to increase the thickness of the liquid crystal layer (the thickness of the liquid crystal layer), but this method has the disadvantage of inhibiting the responsiveness of the liquid crystal display panel, so there is a limit to its application.
It's below the level of Minato ■. The only way to improve the orientation when the cell thickness is selected to this extent is to strengthen the orientation process and increase the number of rubbings, but this method increases the working time. ,
It is difficult to say that this method is necessarily superior, and there has been a desire to develop a more superior alignment treatment method.

[Means for solving problems]

In response to this demand, the present invention provides a method for manufacturing a liquid crystal display panel including an alignment treatment method capable of exhibiting a higher regulating force. , a method for manufacturing a liquid crystal display panel comprising the steps of forming an alignment film and subjecting the alignment film to a rubbing treatment, the liquid crystal display comprising the step of bringing the substrate into contact with hot water after forming the alignment film. It's in the manufacturing method of the panel.

The material of the alignment film is preferably polyvinyl alcohol, polyvinyl phenol, etc., which are also used in the prior art, and the temperature of the hot water is 13b
20”cj to 100”C to ゛-Cl-! S available 1
) However, under 1 atm, the required treatment time is short and the temperature at which bubbles do not occur, i.e., a temperature of about 80°C to 95°C, is suitable. Although it is short, when the hot water temperature is about 80° C., it is preferable to heat the fibers for 5 minutes to 80 minutes or less, and when the hot water temperature is 30° C., it is preferable to heat the fibers for 5 minutes to 80 minutes or less.

[Effect]

The inventor of the present invention believes that the depth of the narrow grooves formed by the alignment treatment is preferably about several tens of amps, and that the surface layer of the alignment film is selectively softened by a thickness of about several tens of amps, and then the rubbing is carried out. We thought that if we could do this, we would be able to form a large number of narrow grooves of that depth in the same direction.

The present invention was completed by embodying this pigeon idea. That is, since the resins normally used as alignment film materials, such as polyvinyl alcohol and polyvinyl phenol, are ~hydrophilic, when the alignment film is treated with hot water, only about a few dozen surface layers of the alignment film are selectively softened. Therefore, if rubbing is performed in this state, narrow grooves in the same direction will be uniformly formed only in this softened surface layer. .

[Example A]

Hereinafter, the alignment treatment step of the method for manufacturing a liquid crystal display panel according to an embodiment of the present invention will be further explained with reference to the drawings.

Refer to Figure 2. A layer 2 of insium tin oxide (hereinafter referred to as ITO) with a thickness of about 10 pm is formed in parallel strips on a glass substrate l with a thickness of 1 to 2 arms, and a layer 2 of polyvinyl alcohol is coated with a thickness of 800 pm. The alignment film 6 is formed by coating the film to about 80%. This coating process can be easily performed using a transfer printing method.The substrate 1 is cured by heating in an inert gas such as nitrogen gas.See Figure 1.The substrate 1 is immersed in a hot bath 3 at about 90°C for about 30 minutes. Then dry. In this step, only about 60 layers of the surface layer with orientation H6 having a thickness of about 600 A are softened.

When rubbing is done using a rubbing machine.

A large number of narrow grooves having the same direction are formed on the surface layer of the alignment film 6 at a depth of 6.
It is formed to about 0 people.

Refer to Fig. 3 Two substrates 1 which have been subjected to the alignment treatment as described above are arranged so that the ITO electrodes 2 formed in parallel strips face each other in orthogonal directions, and the two substrates 1 are arranged in a close-to-face manner. height 5
A wet spacer 4 is provided, the two substrates (2) are bonded together so as to leave a cavity inside, and a liquid crystal 5 is sealed in this cavity to complete the liquid crystal display device.

Referring to FIG. 4, the screen of the liquid crystal display panel manufactured through the above steps was observed in detail using a microscope, and it was confirmed that the number of irregular patterns described above had been significantly reduced. Furthermore, several V is applied between the ITO electrodes 2 of this liquid crystal display panel.
When operated with a voltage of

The hot water treatment of the alignment film according to the gist of the present invention includes the hot water temperature,
There are various possible embodiments depending on the contact time with hot water (immersion time) and the thickness to be softened as parameters. Figure 0 shows a liquid crystal display panel using an alignment film immersed in warm water at 90°C under 1 atm. It is a graph showing the relationship between the number of domains generated (the number of domains generated per crown surface planting of the above-mentioned irregularly shaped pattern) versus hot water treatment time. According to the graph, the effect improves as the hot water treatment time increases up to 0.5 hours, but the effect decreases at higher temperatures. This phenomenon occurs when the hot water treatment time exceeds the appropriate hit time.
It is inferred that this is because the surface layer with a thickness greater than the desired thickness is softened, and narrow grooves in undesired directions are likely to be formed in the rubbing process.

See Figures 5 and 6. Figures 5 and 6 show the number of domains generated/hot water treatment when the same hot water treatment as above is performed in hot water of 70°C and 50°C under 1 atm, respectively. This is a graph showing the processing time. Although there was a tendency for the required treatment time to become longer as the temperature decreased, the degree of effect was generally the same in all cases, and the existence of an optimal temperature was not recognized.

Therefore, from an industrial standpoint, the working time is short, and
Under 1 atm, bubbles do not occur, and the desired effect is easily achieved (if bubbles occur, the effect deteriorates markedly). 1. Hot water at a temperature of about 90°C to 95°C, which is easy to work with. It was concluded that the treatment was the most suitable. In that case, the required processing time is about 5 minutes to about 70 minutes, and about 30 minutes is most suitable.

(Effects of the Invention) As explained above, according to the alignment treatment process of the present invention, after forming a resin film of polyvinyl alcohol, polyvinyl phenol, etc. on an insulating substrate, hot water treatment is performed, and then rubbing is performed. Since the alignment film is supposed to be formed in the following manner, only the surface layer number + A of the alignment film is selectively softened, and by rubbing, fine grooves in the same direction are uniformly formed only in this softened surface layer. Uniform alignment treatment is performed over the entire picture frame, no local alignment defects occur, and the screen is uniform over the entire picture frame.Moreover, the ON/OFF ratio is high, the brightness is high, and the hue and tint are excellent. It is possible to manufacture liquid crystal display panels with

[Brief explanation of drawings]

Figs.
The figure is a cross-sectional view of a liquid crystal display panel manufactured by the method for manufacturing a liquid crystal display panel according to an embodiment of the present invention. It is a graph showing the effect. l...Glass substrate (insulating substrate), 2...IT
O electrode, 3...warm bath, 4...Φ spacer,
5...Liquid crystal, 6...Alignment film. ,,,1. -i Figure 1 Figure 2 Figure 3 Figure 4

Claims (2)

[Claims] (1) In a method for manufacturing a liquid crystal display panel, which includes a step of forming electrodes on an insulating substrate, forming an alignment film, and subjecting the alignment film to a rubbing treatment, after forming the alignment film, the substrate is washed with hot water. A method for manufacturing a liquid crystal display panel, comprising the step of bringing the panel into contact with the liquid crystal display panel. (2) The method for manufacturing a liquid crystal panel according to claim 1, wherein the temperature of the hot water is about 80°C to 95°C, and the treatment time is from 5 minutes to 70 minutes.