JPH063635A - Manufacture of liquid crystal display panel - Google Patents

Abstract

PURPOSE:To improve irregularity in orientation and electro-optic behavior, and ensure the effectiveness of an additive related to a ferroelectric liquid crystal material by using a liquid crystal dropping method for improving filling irregularity conventionally regarded as a problem related to the addition of a polarizing additive to a liquid crystal material. CONSTITUTION:Liquid crystal is mixed with a polarizing additive, and the mixed liquid crystal 12 resulting therefrom is sealed into a syringe 11. Then, the mixed liquid crystal 12 is dropped onto one of liquid crystal panel substrates with ultraviolet(UV) setting seal resin printed, and the other substrate is pasted thereto in vacuum. Thereafter, only a seal section is hardened in a UV setting furnace and cut out, thereby preparing a liquid crystal panel. As a result, the chromatographic phenomenon of the polarizing additive can be reduced, and a liquid crystal panel capable of uniform display can be manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal panel, and more particularly to a method of manufacturing a liquid crystal panel.

[0002]

2. Description of the Related Art Conventionally, liquid crystal panels have been sealed between substrates by a method called a vacuum injection method.

A vacuum injection system will be briefly described (FIG. 2). As shown in FIG.
The sealing resin 22 is printed while leaving (called an injection hole), and an empty panel 23 in which a counter substrate is bonded and cured is placed in a vacuum chamber 24.

A liquid crystal reservoir 25 is installed in the vacuum chamber. After the chamber is evacuated (naturally, the inside of the panel is also vacuumed), the injection hole portion of the empty panel is immersed in the liquid chamber and the vacuum chamber This is a method in which the liquid crystal is sealed due to the difference from the atmospheric pressure by returning to normal pressure.

In this case, the injected liquid crystal material moves upward with time and finally fills the entire panel interior.

The vacuum injection system is disclosed in Japanese Patent Laid-Open No. 49-
For details, see Japanese Patent No. 79543.

[0007]

However, in the conventional injection method, when the additive added to the liquid crystal material has polarity or the miscibility is poor, injection unevenness is likely to occur in the process of filling the liquid crystal, There is a problem that the display quality of the liquid crystal panel is greatly affected.

In view of the above problems, it is therefore an object of the present invention to provide a method of manufacturing a liquid crystal panel of good display quality without uneven injection of liquid crystal.

[0009]

According to the method of manufacturing a liquid crystal panel of the present invention, liquid crystal is dropped and the substrates are attached in a vacuum to seal the liquid crystal.

[0010]

According to the present invention, since the liquid crystal is dropped to fill the liquid crystal, there is no movement of the liquid crystal from the injection hole to the upper part, and therefore, there is little unevenness of injection due to the polar additive.

[0011]

【Example】

(Example 1) An indium-tin oxide film was vapor-deposited and etched (ITO
SE-1 manufactured by Hitachi Chemical Co., Ltd. as an alignment film
Using 50, an alignment film having a predetermined thickness was obtained by a printing method.

As the liquid crystal material, ZLI229 manufactured by Merck Ltd.
3 was used. Cyanobenzene was used as a polar additive (about 3% added). Further, CM-34 (manufactured by Chisso Corporation) was added as a chiral regulator in an amount of 1.5%.

Next, the surface of the polyimide was polished by a usual rubbing method so as to have an orientation ability. The rubbing direction was performed on each of the upper and lower substrates so that a 240 ° twist structure (so-called super twisted nematic system: so-called STN system) was formed.

Onto such a substrate, the above liquid crystal containing an additive was dropped using a microsyringe (Hamilton microsyringe 25 μl capacity). 5 × 2 as the number of drops
Of 10 points (amount of one drop: 2.5 μl).

The total amount of drops was determined in the same amount as the volume in the panel (cell thickness × panel area: 8 μm).
m × 5 cm × 6.25 cm = 25 μl).

An ultraviolet curable resin (for example, a resin obtained by adding 1% of benzoin ethyl ether to polyester acrylate) is seal-printed on the other substrate, and then a spacer (Micropearl 8 μm manufactured by Sekisui Fine Chemical Co., Ltd.) is usually used. It was scattered by the method (~ 150
Pieces / square millimeter).

After the substrate 11 on which the liquid crystal was dropped and the other substrate were bonded together in a vacuum (0.1 Torr), the upper and lower substrates were bonded using a mask so that only the seal portion could be irradiated with ultraviolet rays.

Such a liquid crystal dropping method is described in detail in JP-A-62-10596.

As a comparative example, a sealing resin, a spacer, etc. were installed in the same manner as described above, and a normal empty cell was prepared without dropping liquid crystal.

This empty panel is subjected to ZLI by a vacuum injection method.
2293 liquid crystal was injected to obtain a liquid crystal panel.

By applying a voltage, the uniformity of the electro-optical characteristics of the liquid crystal panel was visually measured.

As a result of the measurement, the panel manufactured by the dropping method had very uniform electro-optical characteristics in the panel surface with respect to the voltage, and there was no problem.

However, according to the vacuum injection method (see FIG. 1), there occurs a phenomenon that the injection hole side 11 starts to change by being sensitive to a low voltage, and as it moves away from the injection hole 12, it starts to respond to a high voltage.

This appears as display unevenness,
It is not preferable as a liquid crystal panel. Further, when no additives were added, such unevenness hardly appeared even in the vacuum injection method.

(Example 2) ITO similar to (Example 1)
A substrate was used, and an aminosilane coupler (A-1120 manufactured by Nippon Unicar Co., Ltd.) was used as an alignment film. A 1% ethanol solution was applied by a spinner to obtain a film thickness of about 100Å.

Orientation ability was obtained on the above-mentioned substrate by a usual rubbing method. The rubbing directions were antiparallel to the upper and lower substrates.

In the same manner as in (Example 1), seal printing was performed on one side of the substrate using an ultraviolet curable resin, and a true thread ball (2.0 μm) manufactured by Catalyst Kasei Co. Sprayed (70 / square millimeter).

On the other hand, a ferroelectric liquid crystal material was dropped on the substrate using a microsyringe in the same manner as in (Example 1). The dropping amount was 60 μl (dripping point: 5 × 2 = 10)
point).

Next, the ferroelectric liquid crystal material used will be described. ZLI1 manufactured by Merck Ltd. as a ferroelectric liquid crystal material
027 was used. Amine compounds as additives

[0030]

[Equation 1]

Alternatively, epoxy compound

[0032]

[Equation 2]

Two of the above were used. These additives have an effect of preventing the burning of the ferroelectric liquid crystal, and the additives are disclosed in JP-A-63-263230, JP-A-63-307389, and JP-A-63-307390.
For example, see JP-A-63-333253.

The additives are not limited to those described above, but primary amines (eg aminobenzene, 1-aminopropane, aminocyclohexane, compounds of formula 1 etc.), secondary amines (eg N-methylaminobenzene etc.), etc. Basic substances or acidic substances such as benzoic acid, stearic acid and nitrobenzoic acid. Alternatively, those having strong polarity such as nitrobenzene, acrylonitrile, and ether compounds (for example, formula 2). Alternatively, triethyleneglycol dimethyl ether, polyethyleneglycol, fluoroalkyl compounds and the like having poor miscibility with liquid crystal may be mentioned.

For examples of such additives, see Japanese Patent Laid-Open No.
3-263230, JP-A-63-307389, JP-A-63-307390, JP-A-63-
For details, see Japanese Patent No. 333253.

The ferroelectric liquid crystal panel thus produced was uniformly oriented and showed uniform optical characteristics against an electric field. The memory characteristics after applying the electric field were also uniform.

In comparison with this, in the vacuum injection ferroelectric liquid crystal panel manufactured in the same manner as in (Example 1), the optical characteristics with respect to the electric field were different on the injection hole side and the opposite side, and the display uniformity was poor.

When no additives were added, such unevenness hardly occurred even in the vacuum injection system.

[0039]

According to the present invention, the liquid crystal filling method when a polar additive is added to the liquid crystal material is carried out by a dropping method different from the conventional vacuum injection method, whereby uneven injection can be eliminated and a uniform display can be obtained. Has the effect.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing uneven injection.

FIG. 2 is a schematic diagram illustrating an injection method.

[Explanation of symbols]

 11 injection hole side 12 injection hole

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Kimura 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Hiroyuki Onishi, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (5)

[Claims] 1. A sealant is disposed on at least one of the opposing electrode substrates, one or more kinds of liquid crystal is placed on at least one of the electrode substrates in a fixed amount, and then at least two of the electrode substrates are attached in vacuum. A method of manufacturing a liquid crystal panel, wherein the liquid crystal is mixed with an additive. 2. The method for producing a liquid crystal panel according to claim 1, wherein the additive has physical properties different from those of the liquid crystal. 3. The method for producing a liquid crystal panel according to claim 1, wherein the additive has polarity. 4. The method for producing a liquid crystal panel according to claim 1, 2 or 3, wherein the additive is basic or acidic. 5. The method for producing a liquid crystal panel according to claim 1, 2, 3, or 4, wherein the liquid crystal is a ferroelectric liquid crystal.