JPH0961823A - Production of liquid crystal display element and liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve display image quality by making the film thickness distribution of oriented films on electrode substrates uniform and to reduce a manufacturing cost by saving liquid crystal oriented film materials. SOLUTION: The liquid crystal oriented films 13, 14 are formed by an oriented film printer which applies a liquid crystal oriented film material 30 on a printing plate 27 by spraying with a spray gun 28, then transferring the liquid crystal oriented film material 30 on the electrode substrates 11, 12 by transfer and contact with the printing plate 27, by which the liquid crystal oriented film material is saved and the film thickness distribution of the liquid crystal oriented films is made uniform.

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 having a liquid crystal alignment film transferred from a printing plate and a liquid crystal display device.

[0002]

2. Description of the Related Art In recent years, liquid crystal display elements having the advantages of thinness, light weight and low power consumption have been used in personal computers such as Japanese word processors and desktop personal computers.
It is often used as a display device for equipment A and the like.

As a liquid crystal composition used for various liquid crystal display elements, a field effect type twisted nematic (TN) type liquid crystal and a super twist (ST) type liquid crystal are generally used.

Of these, T having a molecular arrangement twisted by 90 °
In principle, N-type liquid crystal displays in black and white, exhibits a high contrast ratio and good gradation display properties, and has a fast response speed (several tens of milliseconds). Therefore, simple matrix drive or active matrix drive is used. It is applied to clocks and calculators, and is also applied to full-color display liquid crystal televisions combined with color filters.

On the other hand, the ST type liquid crystal having a molecular arrangement twisted by 90 ° or more has a steep electro-optical characteristic, so that the structure is simple and the manufacturing cost is low even if a switching element such as a thin film transistor or a diode is not provided for each pixel. Has been applied to a large screen device because a large capacity display can be easily obtained by time-division driving using an inexpensive simple matrix type electrode structure.

In a liquid crystal display device having such a field effect type liquid crystal composition, in order to obtain a uniform display image, liquid crystal molecules of the liquid crystal composition held between two electrode substrates are While uniformly orienting the entire surface of the electrode substrate, 2
It is necessary to give a predetermined pretilt angle evenly when a voltage is applied between the electrode substrates.

As described above, in order to uniformly align the liquid crystal composition and to give the liquid crystal composition a uniform pretilt angle, an alignment film made of an organic polymer thin film typified by polyimide is conventionally formed on the surface of the electrode substrate. After filming, rubbing was performed by gently rubbing with a cloth or the like.

Conventionally, the printing apparatus 1 as shown in FIG.
Thus, the alignment film was formed on the surface of the electrode substrate so that the film thickness distribution was uniform. That is, the supplied liquid crystal alignment film material 2
Is applied to the anilox roller 4 by the doctor roller 3 so as to have a uniform thickness, and then temporarily transferred to the offset printing plate 7 on the rotary press 6, and the liquid crystal alignment film material on the offset printing plate 7 is further applied to the electrode. By transferring to the surface of the substrate 8, an alignment film having a uniform thickness was formed on the surface of the electrode substrate.

Further, as another method for forming an alignment film having a uniform thickness on the surface of an electrode substrate, as disclosed in JP-A-62-288813, liquid crystal alignment is performed on the surface of the electrode substrate by using a spray or the like. A method of directly spraying the membrane material was also used.

[0010]

Conventionally, in order to form a liquid crystal alignment film on the surface of an electrode substrate, a liquid crystal alignment film material is once applied to an anilox roller, then transferred to an offset printing plate, and then further transferred to an electrode substrate. A method of obtaining by transferring or a method of obtaining by directly spraying the liquid crystal alignment film material on the surface of the electrode substrate has been implemented.

Therefore, in the former case, although the uniformity of the film thickness of the liquid crystal alignment film on the surface of the electrode substrate can be improved,
The liquid crystal alignment film material must be applied to the doctor roller and the anix roller before being transferred to the electrode substrate surface, and the doctor roller and the anix roller are used in comparison with the amount of the liquid crystal alignment film material transferred to the electrode substrate surface. A large amount is attached to the anix roller, and the use efficiency of the liquid crystal alignment film material is remarkably reduced, resulting in poor economy.

On the other hand, in the latter, since the liquid crystal alignment film material is directly sprayed on the electrode substrate, the liquid crystal alignment film material is not wasted, and good use efficiency of the liquid crystal alignment film material is obtained. However, since there is no step of flattening the liquid crystal alignment film material by an indirect member, the film thickness of the liquid crystal alignment film on the electrode substrate surface becomes non-uniform, and as a result the uniformity of the alignment direction of liquid crystal molecules and pretilt There is a problem that the uniformity of the corners is deteriorated.

Therefore, the present invention eliminates the above-mentioned problems, and maintains the uniformity of the film thickness distribution at the time of forming a liquid crystal alignment film on the surface of an electrode substrate and reduces the wasteful consumption of the liquid crystal alignment film material as much as possible. However, it is an object of the present invention to provide a method of manufacturing a liquid crystal display element and a liquid crystal display element, which can improve the use efficiency of the liquid crystal alignment film material and have excellent economical efficiency.

[0014]

According to a first aspect of the present invention for solving the above problems, there is provided a step of forming a first electrode on a first electrode substrate and a step of forming a first electrode on a second electrode substrate. A second electrode, a step of forming a liquid crystal alignment film on the first electrode and a film of a liquid crystal alignment film on the second electrode, and the first electrode so that the liquid crystal alignment film faces each other with a gap therebetween. In a method of manufacturing a liquid crystal display device, which comprises a step of assembling a substrate and the second electrode substrate, and a step of enclosing a liquid crystal composition in the gap, the step of forming the liquid crystal alignment film is a printing plate surface of a printing device. A step of uniformly dispersing the liquid crystal alignment film material on the
The printing plate on which the liquid crystal alignment film material is dispersed is the first
The electrode substrate surface and the second electrode substrate surface of
And a step of transferring the liquid crystal alignment film material on the surface of the printing plate onto the first electrode and the second electrode.

The present invention for solving the above-mentioned problems provides a first electrode substrate having a first electrode,
A second electrode substrate having a second electrode, and a first alignment film formed on the first electrode by rolling contact with a printing plate surface of a printing device on which a liquid crystal alignment film material is uniformly dispersed. A second alignment film formed on the second electrode by rolling contact with the surface of the printing plate of the printing device on which the liquid crystal alignment film material is uniformly dispersed; The second
And a liquid crystal composition filled in a gap between the first electrode substrate and the second electrode substrate that face each other so that the liquid crystal alignment films face each other.

[0016]

The present invention is configured as described above, and by transferring the liquid crystal alignment film material once dispersed on the printing plate onto the electrode substrate, the liquid crystal alignment film material is once flattened on the printing plate and then the electrode is formed. Since it is transferred to the substrate surface, the film thickness distribution of the alignment film on the electrode substrate is excellent, and good alignment characteristics can be obtained, and the liquid crystal alignment film material consumption due to adhesion to the doctor roller or anix roller is reduced. In addition, the liquid crystal alignment film material can be used efficiently and the economy can be improved.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic cross-sectional view of a simple matrix type liquid crystal display element 10. The first and second electrode substrates 1 are shown in FIG.
The liquid crystal composition 16 of TN type is held between the first and the second liquid crystal alignment films 13 and 14 made of polyimide via the first and second liquid crystal alignment films 13 and 14, and the polarizing plates 17 and 18 are provided.

Here, the first and second electrode substrates 11 and 12
Is ITO on the first and second glass substrates 20 and 21.
Each has a first electrode 20a and a second electrode 21a made of (Indium Tin Oxide), and liquid crystal alignment films 13 and 14 are formed on the surfaces thereof.

Next, the manufacturing process of the liquid crystal display element 10 will be described. First, an ITO film is formed on the first and second glass substrates 20 and 21 by a sputtering method, and then the ITO film is photoetched by a photolithography technique to pattern-form the first and second electrodes 20a and 21a. .

Subsequently, the first and second electrodes 20a, 21
The liquid crystal alignment films 13 and 14 are printed and applied on the surface a in the following manner. First, the first electrode substrate 11 is washed with a neutral detergent and then dried at 120 ° C. for 20 minutes.

On the other hand, in the alignment film printing device 24, an air pressure of 2.0 kgf / c is applied by a two-fluid spray gun 28 onto an offset printing plate 27 attached to a rotary press 26.
m ² , liquid crystal alignment film material supply rate 0.5 ml / min. 2.0 of AL-1051 (manufactured by Japan Synthetic Rubber Co., Ltd.) under the conditions
The liquid crystal alignment film material 30 composed of a solution of wt% is sprinkled for 5 seconds, and the liquid crystal alignment film material 30 is applied onto the offset printing plate 27.

Then, the first electrode substrate 11 is transferred to the offset printing plate 27, and the liquid crystal alignment film 30 scattered on the offset printing plate 27 is transferred to the first electrode substrate 11 side.
Then, the liquid crystal alignment film material 30 on the first electrode substrate 11 is set to 1
After drying at 00 ° C. for 1 minute, it is heated and baked at 180 ° C. for 30 minutes to form the first liquid crystal alignment film 13 on the surface of the first electrode substrate 11. Also, on the second electrode substrate 12, after the second liquid crystal alignment film 14 is formed in the same manner as the first electrode substrate 11, when the two electrode substrates 11 and 12 are opposed to each other, the liquid crystal composition 16 is formed. Both liquid crystal alignment films 1 so that liquid crystal molecules are twisted 90 °
Rubbing processing is performed on Nos. 3 and 14.

After that, the sealant 31 is printed around the first electrode substrate 11, and the spacers 32 are evenly dispersed. Then, the electrode substrates 11 and 12 are opposed to each other and the sealant 31 is cured to form a liquid crystal cell. Create. And this liquid crystal cell has ZL
A liquid crystal composition 16 made of I-1132 (manufactured by E. Merck) is injected and sealed, and then polarizing plates 17 and 18 are attached to obtain a liquid crystal display element 10.

The liquid crystal display device 10 thus obtained
The pretilt angle was about 4.0 °, and the pretilt direction was the direction following the rubbing direction. When an image is displayed on the liquid crystal display element 10, a good display can be obtained because the alignment direction and the pretilt angle are uniform, and the liquid crystal alignment film material 30 used when the liquid crystal alignment films 13 and 14 are formed. The usage efficiency is as high as about 70%, and all are effectively used except those scattered around the offset printing plate 27.

According to this structure, the liquid crystal alignment film material 30
Is not directly sprayed on the surfaces of the electrode substrates 11 and 12, but is once sprayed on the offset printing plate 27, flattened once, and then transferred from the offset printing plate 27 onto the electrode substrates 11 and 12. The liquid crystal alignment films 13 and 14 on the films 11 and 12 have a uniform film thickness distribution, are excellent in alignment property, and are uniform in alignment direction and pretilt angle, so that good display quality can be obtained. Further, the liquid crystal alignment film material 30 is directly sprayed on the offset printing plate 27, and then the electrode substrates 11, 1 are formed.
Since it is transferred to No. 2, it is possible to improve the efficiency of use and reduce the manufacturing cost.

Next, a second embodiment of the present invention will be described. This embodiment is the spray gun 2 of the first embodiment.
In place of No. 8, the liquid crystal alignment film material was sprayed on the offset printing plate by using an ink jet, and the other conditions are exactly the same as in the first embodiment. However, in this embodiment as well, the alignment film on the electrode substrate Uniform film thickness distribution, orientation direction,
Since the pretilt angles are uniform, excellent display quality can be obtained, and the liquid crystal alignment film material has a usage efficiency of 90%.
It is higher than that of the above embodiment, and the economical efficiency is further improved.

On the other hand, the same liquid crystal alignment film material 30 as in the first embodiment is applied to the anilox roller 4 by the doctor roller 3 using the conventional printing apparatus 1 shown in FIG. After being applied in the same manner, it is once transferred to the offset printing plate 7 on the rotary press 6, and the liquid crystal alignment film material 30 on the offset printing plate 7 is further transferred to the surfaces of the electrode substrates 11 and 12 to obtain the first embodiment. Electrode substrate 1 in the example
A liquid crystal alignment film having a uniform thickness was formed on the surfaces of Nos. 1 and 12 to obtain (Comparative Example 1).

This (Comparative Example 1) is similar to that of the electrode substrates 11 and 12.
Since the liquid crystal alignment film formed on the surface has a uniform film thickness distribution, excellent display quality can be obtained as in the first embodiment, but the liquid crystal alignment film material is also used for the doctor roller 3 and the anix roller 4. Since it is supplied, the use efficiency of the liquid crystal alignment film material is remarkably reduced to 10%.

Next, the surfaces of the electrode substrates 11 and 12 of the first embodiment are masked with the alignment film forming regions left, and the same liquid crystal alignment film material 30 as in the first embodiment is directly applied using a spray gun. It was applied by spraying and a liquid crystal alignment film was formed on the surfaces of the electrode substrates 11 and 12 to obtain (Comparative Example 2).

In this (Comparative Example 2), the use efficiency of the liquid crystal alignment film material was almost the same as that of the first embodiment, but the liquid crystal alignment film material was not flattened at all and was applied to the surfaces of the electrode substrates 11 and 12. Since it is applied by spraying, the film thickness distribution of the liquid crystal alignment film formed on the surfaces of the electrode substrates 11 and 12 becomes non-uniform, the alignment characteristics are remarkably inferior, and the display defects locally occur due to the film thickness non-uniformity, and the display quality is Is significantly inferior.

The present invention is not limited to the above-described embodiment, and modifications can be made without departing from the spirit of the invention. For example, the liquid crystal display device may be driven by an active matrix system, The liquid crystal alignment film material is not limited,
The spraying method may also be US (ultrasonic atomization) spraying, and the spraying conditions are arbitrary.

[0032]

As described above, according to the present invention, the liquid crystal alignment film material, which is sprayed on the surface of the printing plate and is once flattened, is transferred to the surface of the electrode substrate to form the alignment film. Therefore, it is possible to form an alignment film having a uniform film thickness distribution, excellent alignment properties, and uniform alignment direction and pretilt angle, thereby obtaining a liquid crystal display device having good display quality without causing display defects. To be

Moreover, the liquid crystal alignment film material is not supplied to the coating roller and the like, and its use efficiency is improved.
Economical efficiency is improved by reducing manufacturing costs.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a liquid crystal display element of a first embodiment of the present invention.

FIG. 2 is a schematic explanatory diagram showing a method of forming a liquid crystal alignment film according to the first embodiment of the present invention.

FIG. 3 is a schematic explanatory view showing a conventional method for producing a liquid crystal alignment film.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Liquid crystal display element 11 ... 1st electrode substrate 12 ... 2nd electrode substrate 13 ... Liquid crystal alignment film 14 ... Liquid crystal alignment film 16 ... Liquid crystal composition 24 ... Alignment film printer 27 ... Offset printing plate 28 ... Two-fluid spray Gun 30: Liquid crystal alignment film material

Claims (2)

[Claims] 1. A step of forming a first electrode on a first electrode substrate, a step of forming a second electrode on a second electrode substrate, and a step of forming the first electrode and the second electrode. Forming a liquid crystal alignment film on each of the electrodes, assembling the first electrode substrate and the second electrode substrate so that the liquid crystal alignment film faces each other with a gap, and forming a liquid crystal composition in the gap. In the method for manufacturing a liquid crystal display element, which comprises a step of encapsulating, the step of forming the liquid crystal alignment film includes a step of uniformly dispersing the liquid crystal alignment film material on the surface of a printing plate of a printing device, and the liquid crystal alignment film material being dispersed. The printing plate that has been subjected to the first
The electrode substrate surface and the second electrode substrate surface of
A step of transferring the liquid crystal alignment film material on the surface of the printing plate onto the first electrode and the second electrode, the method of manufacturing a liquid crystal display device. 2. A transfer of a first electrode substrate having a first electrode, a second electrode substrate having a second electrode, and a printing plate surface of a printing device on which a liquid crystal alignment film material is uniformly dispersed. By contacting the first alignment film formed on the first electrode by contact with the surface of the printing plate of the printing device on which the liquid crystal alignment film material is evenly spread, and then on the second electrode. The second alignment film to be formed and the first liquid crystal alignment film and the second liquid crystal alignment film are sealed in a gap between the first electrode substrate and the second electrode substrate which face each other so as to face each other. A liquid crystal display device, comprising: