JPH06342137A - Liquid crystal panel and production thereof - Google Patents

Abstract

PURPOSE:To uniformalize the voltage characteristic of a liquid crystal panel and to prevent the generation of display defect of the liquid crystal by widely spreading the liquid crystal dropped on a substrate. CONSTITUTION:A trace quantity of a fluorinated surfactant is previously added into the liquid crystal and stirred. Thus, the surface tension of the liquid crystal is extremely decreased. the liquid crystal 14 having the surfactant added is dropped on the upper side of an oriented film 12 on one of the substrate 11 formed with a seal 15, the dropped liquid crystal 14 widely spreads without making droplets to cover the full surface of the oriented film 12. After that, the panel having uniform cell thickness is produced by sticking the other substrate to the substrate 11 and photosetting the seal resin.

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 having a liquid crystal filled by a drop-and-paste injection method and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, as a method of filling a liquid crystal material into a panel, as described in JP-A-49-79543, it is provided on the outer peripheral portion of an envelope having a slit inside. A vacuum injection method in which the injection hole is immersed in the liquid crystal in the liquid crystal reservoir in a vacuum and the atmospheric pressure is returned to inject the liquid crystal into the slit of the envelope is described in Japanese Patent Application No. 62-10596. As described above, there is a bonding injection method in which a liquid crystal is dropped on at least one of the two substrates and the two substrates are bonded in a vacuum to manufacture a liquid crystal panel.

The vacuum injection method has a very slow liquid crystal filling speed and the like as compared with the bonding injection method, and it can be said that the drop bonding injection method is superior in the construction method.

Hereinafter, a conventional method of manufacturing a liquid crystal panel in which a liquid crystal is filled using a drop-bonding injection method will be described with reference to the drawings.

FIG. 2 shows the above-mentioned conventional method for manufacturing a liquid crystal panel. (A) and (b) show the state of the liquid crystal after being dropped on the substrates, and (c) shows the two substrates. The state of the liquid crystal after pasting is shown.

First, an alignment film material is applied to one of the substrates 21 and cured to form an alignment film 22 on the substrate 21. After that, the substrate 21 is subjected to an alignment treatment by a rubbing method. Then, the liquid crystal 24 is dropped by the syringe 23 on the upper side of the alignment film 22 on the substrate 21 which has been subjected to the alignment treatment (FIG. 2A).
reference).

The dropped liquid crystal 24 becomes a droplet with a contact angle θ due to the balance between the critical surface tension of the alignment film 22 and the surface tension of the liquid crystal 24 itself (see FIG. 2B).

Thereafter, the substrate 21 and the other substrate are adhered to each other, so that the liquid crystal 24 in the form of liquid drops is spread to have a uniform liquid crystal cell thickness (see FIG. 2C). In addition, in FIG. 2, reference numeral 25 indicates a seal.

[0009]

However, in the liquid crystal panel shown in FIG. 2 (c) manufactured by the above-mentioned conventional manufacturing method, the liquid crystal which is in the form of droplets before being bonded to the liquid crystal 24 in the liquid crystal cell. There is a problem in that there is a difference between the voltage characteristics of the drop portion 24a and the characteristics of the liquid crystal extended portion 24b expanded by bonding in the liquid crystal 24 with respect to the voltage, resulting in defective display.

The present invention has been made in view of the above, and an object of the present invention is to prevent the occurrence of a display defect of a liquid crystal panel.

[0011]

The cause of the above-mentioned display failure of the liquid crystal panel is not known in principle, but the liquid crystal panel shown in FIGS. 2 (a) and 2 (b) is formed. It is considered that if the state is long in time, various impurities or polar substances in the liquid crystal material may seep out at the contact portion between the liquid crystal 24 and the alignment film 22 to cause a phenomenon such as adsorption.

The present invention has been made on the basis of such knowledge, and the surface tension of the liquid crystal is lowered by adding an additive such as a surfactant to the liquid crystal material to spread the liquid crystal dropped on the substrate. By increasing the value, the characteristics of the liquid crystal panel with respect to the voltage are made uniform.

Specifically, in the solution means taken by the invention of claim 1, the liquid crystal is dropped on at least one of the two substrates, and the two substrates are bonded so as to face each other with the liquid crystal interposed therebetween. The liquid crystal panel is formed by adding an additive to the liquid crystal to reduce the surface tension of the liquid crystal before the liquid crystal is dropped on at least one of the two substrates.

According to a second aspect of the invention, in addition to the constitution of the first aspect of the invention, the additive is a surfactant.

According to a third aspect of the present invention, in addition to the configuration of the first aspect of the invention, the additive is a silicone-based substance.

According to a fourth aspect of the present invention, in addition to the constitution of the first aspect of the invention, the additive is a fluorine-based substance.

Further, the solution means taken by the invention of claim 5 is the first method for dropping liquid crystal on at least one of the two substrates.
And a second step of adhering the two substrates so that they face each other with the liquid crystal interposed therebetween, and before the first step. The liquid crystal is configured to include a step of adding an additive that lowers the surface tension of the liquid crystal.

According to a sixth aspect of the present invention, in addition to the constitution of the fifth aspect, the above-mentioned additive is a surfactant.

According to a seventh aspect of the invention, in addition to the constitution of the fifth aspect of the invention, the additive is a silicone type substance.

According to the invention of claim 8, the composition of the invention of claim 5 is such that the additive is a fluorine-based substance.

[0021]

According to the constitutions of claims 1 to 4, in the liquid crystal panel, since the liquid crystal is added with an additive for lowering the surface tension of the liquid crystal, the liquid crystal is dripped on the substrate at the stage of manufacturing the liquid crystal panel. At this time, the liquid crystal does not form a liquid droplet and spreads evenly over the entire surface of, for example, the alignment film on the substrate, so that partial adsorption of ions, impurities, etc. is eliminated, and uniform display characteristics with respect to voltage can be obtained. .

According to the invention of claims 5 to 8,
In the method of manufacturing a liquid crystal panel, since an additive that lowers the surface tension of the liquid crystal is added to the liquid crystal before the liquid crystal is dropped, the liquid crystal does not form a liquid droplet in the first step of dropping the liquid crystal on the substrate, and for example, the orientation Since it spreads evenly over the entire surface of the film, partial adsorption of ions, impurities, etc. is eliminated. Therefore, the display characteristics of the manufactured liquid crystal panel with respect to the voltage can be made uniform.

[0023]

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

(First Embodiment) In a liquid crystal panel according to the first embodiment, liquid crystal is dropped on at least one of two substrates, and the two substrates are attached so as to face each other with the liquid crystal interposed therebetween. The liquid crystal is added with a fluorine-based surfactant that lowers the surface tension of the liquid crystal before being dropped on at least one of the two substrates.

FIG. 1 is a schematic view showing a method of manufacturing a liquid crystal panel according to the first embodiment as described above, showing a state of liquid crystal after being dropped on a substrate.

In the method of manufacturing the liquid crystal panel according to the first embodiment, first, the ITO formed on the one substrate 11 is used.
An alignment film material (Optomer AL-2061 manufactured by Japan Synthetic Rubber Co., Ltd.) is applied on the upper side of the film (indium oxide film) by a printing method, and the alignment film material is cured by heating at 190 ° C. for 1 hour to form a substrate 11 Then, the alignment film 12 is formed. After that, the substrate 11 is subjected to an alignment treatment by a rubbing method so that the substrate 11 is twisted to the right by 90 degrees (TN alignment). Then, the seal 15 is formed on the orientation-treated substrate 11 with a photocurable resin mixed with a gap forming spacer (Nippon Electric Glass Co., Ltd. glass fiber 5 μm diameter).

Here, in advance, a liquid crystal (ZLI4 manufactured by Merck & Co., Inc.
Chiral agent S811 manufactured by Merck & Co., Ltd. is applied to 792 at a pitch of 80 μm.
m)), for example, a fluorine-containing surfactant Florard FC-430 (manufactured by Sumitomo 3M Co., Ltd.) is added in a small amount and stirred. As a result, the surface tension of the liquid crystal becomes very small.

Then, as shown in FIG. 1, when the liquid crystal 14 to which the additive is added is dropped onto the upper side of the alignment film 12 on the substrate 11 on which the seal 15 is formed by the syringe 13, the surface tension of the liquid crystal 14 is reduced. Since the critical surface tension of the alignment film 12 is much smaller than that of the alignment film 12, the dropped liquid crystal 14 does not form a liquid droplet and shows a large spread and covers the entire surface of the alignment film 12 before the other substrate is bonded to the substrate 11.

Thereafter, the substrate 11 and the other substrate on which Sekisui Fine Chemical Co., Ltd. Micropearl 5 μm in diameter was evenly sprayed for cell thickness adjustment are bonded together, and the sealing resin is photocured to form a uniform cell thickness panel ( 5 μm).

In the liquid crystal panel according to the first embodiment as described above, uniform display characteristics can be obtained with respect to voltage, and there is no problem in terms of reliability.

(Second Embodiment) The liquid crystal panel according to the second embodiment is similar to the liquid crystal panel according to the first embodiment.
A liquid crystal is dropped on at least one of the two substrates, and the two substrates are bonded to each other with the liquid crystal sandwiched therebetween.

The liquid crystal panel according to the second embodiment has two
A super twisted nematic cell (STN cell) having a twist of 40 degrees and a cell thickness of 6 μm, and one of the substrates has an alignment film material SE4110 manufactured by Nissan Chemical Industries, Ltd.
Is applied and heated at 200 ° C. for 1 hour to form a cured alignment film.

At the manufacturing stage, a small amount of, for example, a commercially available silicone oil SH200 (manufactured by Toray Dow Corning Silicone Co., Ltd.) is added to the liquid crystal (ZLI2293 manufactured by Merck) and stirred in advance. As a result, the surface tension of the liquid crystal becomes very small. Then, when the liquid crystal to which the additive is added is dropped onto the substrate by a syringe, the surface tension of the liquid crystal is smaller than the critical surface tension of the alignment film. Therefore, as in the first embodiment, the dropped liquid crystal has a droplet shape. However, the liquid crystal covers the entire surface of the alignment film before the other substrate is bonded to the above one substrate by showing a large spread.

After that, the one substrate and the other substrate are attached to each other, and the sealing resin is photo-cured to prepare a uniform cell thickness panel.

Also in the liquid crystal panel according to the second embodiment as described above, uniform display characteristics can be obtained with respect to voltage, and there is no problem in terms of reliability.

[0036]

As described above, according to the liquid crystal panel of the first aspect of the present invention, since the liquid crystal is added with an additive that lowers the surface tension of the liquid crystal, the liquid crystal panel is produced at the stage of manufacturing the liquid crystal panel. When the liquid crystal is dropped on the liquid crystal, the liquid crystal does not form a liquid drop and spreads evenly over the entire surface of, for example, the alignment film on the substrate, so that partial adsorption is eliminated and uniform display characteristics with respect to voltage can be obtained. Further, claim 2
According to the liquid crystal panel of the invention of 3 or 4, the surface tension of the liquid crystal can be easily and surely reduced.

According to the method of manufacturing a liquid crystal panel according to the fifth aspect of the invention, since the additive for lowering the surface tension of the liquid crystal is added to the liquid crystal before the dropping, the liquid crystal drops in the step of dropping the liquid crystal on the substrate. Since it does not have a shape and spreads evenly over the entire surface of, for example, the alignment film on the substrate, partial adsorption is eliminated. Therefore, according to this invention, the liquid crystal panel according to the invention of claim 1 can be reliably manufactured. Furthermore, according to the liquid crystal panel manufacturing method of the sixth, seventh or eighth aspect of the invention, the surface tension of the liquid crystal can be easily and surely reduced.

As described above, according to the present invention, since the characteristics of the liquid crystal panel with respect to the voltage can be made uniform, it is possible to prevent the display failure of the liquid crystal panel from occurring and to improve the display quality and the yield. You can

[Brief description of drawings]

FIG. 1 is a schematic view showing a state of a liquid crystal after dropping in a liquid crystal panel manufacturing method according to a first embodiment of the present invention.

FIG. 2 shows a conventional method for manufacturing a liquid crystal panel,
(A) is a schematic diagram showing a state of liquid crystal after dropping in the conventional method for producing a liquid crystal panel, and (b) is a cross-sectional view showing a state of liquid crystal after dropping in the conventional method for producing a liquid crystal panel. And (c) is a cross-sectional view showing a state of the liquid crystal after the two substrates are bonded together.

[Explanation of symbols]

 11 substrate 12 alignment film 13 syringe 14 liquid crystal 15 seal

Claims (8)

[Claims] 1. A liquid crystal panel in which a liquid crystal is dropped on at least one of two substrates and the two substrates are bonded so as to face each other with the liquid crystal sandwiched therebetween. 2. A liquid crystal panel, wherein an additive that lowers the surface tension of the liquid crystal is added before the liquid crystal is dropped onto at least one of the substrates. 2. The liquid crystal panel according to claim 1, wherein the additive is a surfactant. 3. The liquid crystal panel according to claim 1, wherein the additive is a silicone-based substance. 4. The liquid crystal panel according to claim 1, wherein the additive is a fluorine-based substance. 5. A first step of dropping liquid crystal onto at least one of the two substrates, and a second step of bonding the two substrates so that they face each other with the liquid crystal interposed therebetween. A method for producing a liquid crystal panel, comprising the step of adding an additive for reducing the surface tension of the liquid crystal to the liquid crystal before the first step. 6. The method for manufacturing a liquid crystal panel according to claim 5, wherein the additive is a surfactant. 7. The method for manufacturing a liquid crystal panel according to claim 5, wherein the additive is a silicone-based substance. 8. The method of manufacturing a liquid crystal panel according to claim 5, wherein the additive is a fluorine-based substance.