JPH10239694A - Manufacturing method of liquid crystal display device - Google Patents

Abstract

(57) Abstract: A method of manufacturing a liquid crystal display device, in which liquid crystal is dropped inside a sealant formed on one glass substrate, and the other glass substrate is overlapped and liquid crystal is injected into a liquid crystal cell. Prevents the liquid crystal from passing over the sealant. SOLUTION: One glass substrate 6 coated with the sealant 2 is held on a fixed base 9 in a superposing apparatus, and a glass substrate near the inside of the sealant 2 is provided by a cooling part 12 provided on the fixed base 9. The surface is cooled to a temperature not higher than the temperature at which the viscosity of the liquid crystal 4 becomes 100 cP or more, and the surface of the glass substrate inside the sealant 2 is cooled to reduce the fluidity of the spread liquid crystal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a liquid crystal display device.

[0002]

2. Description of the Related Art A liquid crystal display device is already known as a device in which a liquid crystal layer is provided in a gap between two glass substrates with electrodes and characters, numerals, figures, pictures, etc. are displayed by an electro-optic effect. Several methods described below are known as a liquid crystal injection method for such a liquid crystal display device.

(1) Two glass substrates with electrodes are attached with a sealant, a part of the sealant is released, and a liquid crystal cell provided with a liquid crystal injection port and a liquid crystal dish containing a liquid crystal can be evacuated. Then, the container is evacuated, the liquid crystal injection port is immersed in the liquid crystal, the container of the exhaust system is returned to the atmospheric pressure, and the liquid crystal is injected using the pressure difference between the inside and outside of the liquid crystal cell (see FIG. 1; , Vacuum injection method). Although this is the most commonly used method, the use of a liquid crystal dish requires the use of more liquid crystals than necessary.

(2) Two glass substrates with electrodes are bonded with a sealant, a plurality of places of the sealant are released, and one liquid crystal inlet and one or more outlets are provided. A method of supplying a liquid crystal by connecting an injection connector (Japanese Patent Laid-Open No. 7-281200). Liquid crystal can be used without waste, and a vacuum vessel is not required.

(3) In a vacuum vessel, liquid crystal is dropped inside a sealant formed on one of the electrode-attached glass substrates, and a liquid crystal is dropped on the liquid crystal through an electrically insulating spacer such as polyethylene beads or silica beads. And a method of superposing another glass substrate with electrodes (refer to FIG. 2, hereinafter referred to as a vacuum superposition method) (Japanese Patent Laid-Open No. 63-179323).

[0006] Of these injection methods, the injection methods (1) and (2) have a problem that the time required for liquid crystal injection depends on the screen size, so that large-sized liquid crystal cells lack mass productivity. doing. In addition, since there is a liquid crystal injection port, it is necessary to perform a step of sealing the injection port portion with an ultraviolet curable resin or the like after the liquid crystal is injected. It is a problem. On the other hand, (3) the injection method is considered to be promising as a method for manufacturing a large-sized liquid crystal cell because the time required for liquid crystal injection hardly depends on the screen size. Further, since there is no injection port, a sealing process is not required.

[0007]

However, the method for injecting liquid crystal in a liquid crystal display device by the vacuum superposition method (3) has the following disadvantages. That is, when one of the glass substrates is overlapped, the liquid crystal expands and overflows outside the sealant, which significantly reduces the adhesiveness between the sealant and the glass substrate. It has become. As described above, in order to put the liquid crystal injection method by superposition into practical use, it is an essential condition that the liquid crystal does not jump over and overflow the sealant before the glass substrate on which the sealant is formed and the other glass substrate are bonded to each other. It is. As one means for solving this problem, it has been proposed to apply a liquid crystal so as to be similar in size to a sealant when dropping the liquid crystal (Japanese Patent Laid-Open No. 63-179323).
No.). However, even if these means are adopted, the liquid crystal injection method is still difficult to manufacture with good reproducibility.

[0008]

In order to solve the above-mentioned problems, the present invention is directed to a method in which a liquid crystal is dropped inside a sealant formed on one glass substrate, and the other glass substrate is overlapped with the liquid crystal. In a method of manufacturing a liquid crystal display device in which liquid crystal is injected into a cell, the glass substrate coated with the sealing agent is held on a fixed base in the overlaying apparatus, and the sealing agent is cooled by a cooling portion provided on the fixed base. By cooling the glass substrate surface near the inner side to a temperature below which the viscosity of the liquid crystal becomes 100 cP or more, the fluidity of the spread liquid crystal is reduced,
It is characterized in that two glass substrates are overlapped while preventing liquid crystal from passing over the sealant.

The viscosity of the liquid crystal is several tens of cP (centipoise) at around room temperature. However, when the temperature is lower than 0 ° C., the viscosity is remarkably increased, the fluidity is reduced, and when the temperature is lower than the glass transition point, the fluidity is lost. I do. For example, the viscosity of ZLI1132, a standard liquid crystal material, is 28 cP at 20 ° C and 1 at 0 ° C.
10 cP, 820 cP at minus 20 ° C, minus 3
At 0 ° C., it is 3,870 cP. In the present invention, the cooling temperature of the glass substrate at the time of superposition is not particularly limited, but in order to prevent the liquid crystal from exceeding the sealant, the liquid crystal material is set to a temperature not higher than 100 cP or higher. is required. For example, the temperature of the ZLI1 132 may be set to 0 ° C. or less.

As a method for cooling the glass substrate, the simplest method is to provide a cooling portion as shown in FIG. 3 on a table for fixing the glass substrate, which is provided in a vacuum-applicable overlaying apparatus. In addition, in order to prevent dew condensation on the glass substrate, it is preferable to start cooling after the inside of the superposing apparatus is evacuated.

The shape of the cooling part in the cooling part is preferably a rectangular shape similar to the sealant as shown in FIG.
It is preferable that the central portion of the glass substrate onto which the liquid crystal is dropped is insulated from the cooling portion so that the liquid crystal can be spread.
Considering that the height of the liquid crystal is not much larger than the thickness of the sealant, it is effective for bonding the glass substrates together. Is preferably larger. FIG.
FIG. 2 illustrates a glass part cooled when a glass substrate having a sealant formed on a cooling part having a rectangular cooling part is held.

As a method of cooling the cooling portion, the existing method of cooling by circulating an antifreeze solution is the simplest, and the temperature control is also easy. A method of circulating a cooled nitrogen gas or the like is also possible.

The method of dropping the liquid crystal may be such that the liquid crystal is dropped inside the cooled portion, and the shape and the number of dropping points are not particularly limited. However, in order to enhance the cooling effect, it is preferable to cool the liquid crystal to about 10 ° C. in advance.

According to the present invention, it is possible to prevent the liquid crystal from overflowing the sealant with good reproducibility by the liquid crystal injection method by the vacuum dropping method. Further, as has been conventionally known, since the injection time is not so affected by the screen size, this is an effective liquid crystal injection method in a method for manufacturing a large-sized liquid crystal display device. Also, since there is no liquid crystal injection port,
It is possible to avoid the occurrence of contamination and bubbles in the liquid crystal cell, which are observed by the vacuum injection method.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION A 270 mm
A transparent glass substrate (long side) × 200 mm (short side), 1.1 mm thick and polished surface was used. A signal electrode, a pixel electrode and the like were formed on one glass substrate A, and an alignment film on the outermost surface was formed. In this embodiment, polyimide is adopted as an alignment film, applied by a printing machine and baked (250
(° C./30 minutes), the film thickness was about 0.1 μm. After that, an alignment process was performed on the surface of the alignment film to align the liquid crystal. A rubbing machine (FS-55R type, manufactured by Fujioka) was used for the orientation treatment, and a rubbing roll (diameter: 75φ × length: 600 mm) was made of rayon and buff cloth at a rotational speed of 1300 rpm. On the other glass substrate B, a common electrode was formed, and three color filters of red, blue, and green in a stripe shape and a black matrix were provided. The same polyimide as the alignment film on the glass substrate A was applied on the color filter, and rubbing was performed under the same conditions.

On one glass substrate A, a sealant (ultraviolet curable resin adhesive) containing an appropriate amount of spacer beads (manufactured by Sekisui Chemical) having an outer diameter of 8 μm is placed on the glass substrate A using a seal mask. Printed. The display portion of this liquid crystal cell is about 10 inches diagonally (200 mm × 150 mm), and a sealant having a shape slightly larger than this area is applied.

The glass substrate A coated with the sealing agent is placed in a vacuum container, and a rectangle (short side;
130 mm, a long piece; 180 mm).
Was dropped. After dropping the liquid crystal, evacuate to 0.
After reducing the pressure to 1 Torr and removing the air dissolved in the liquid crystal, the inside of the sealant on the glass substrate was reduced to -10 ° C.
And cooled. Another upper glass substrate B was superposed in parallel from above the lower glass substrate A. At this time, the liquid crystal was expanded, but the flow of the liquid crystal was hindered in the cooled portion of the lower glass substrate A, and the liquid crystal did not protrude outside the sealant. Lastly, the sealant was cured by irradiating ultraviolet rays while pressing the two substrates using a press. The inside of the liquid crystal cell was sandwiched between spherical polymer beads, and the gap was 8.0 μm when the liquid crystal was sealed.

In this vacuum vessel, the superposition of two glass substrates was repeated 30 times, and in each case, the liquid crystal could be injected with good reproducibility in a short time. In any of the liquid crystal cells, generation of bubbles and peeling of the sealant were not observed.

[0019]

According to the method of manufacturing a liquid crystal display device of the present invention, the liquid crystal can be prevented from overflowing beyond the sealant by the liquid crystal injection method by superposition, and the production management is easy and the reproducibility is improved. It is an excellent tool. Further, since there is no injection port, contamination in the liquid crystal cell and mixing of bubbles can be prevented.
Further, as conventionally known, a method of manufacturing a large-sized liquid crystal display device is a liquid crystal injection method capable of greatly reducing the time for injecting liquid crystal.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a liquid crystal injection method of a conventional liquid crystal display device.

FIG. 2 is an explanatory diagram of a liquid crystal injection method of the present invention.

FIG. 3 is an explanatory diagram of a liquid crystal injection method of the present invention.

FIG. 4 is an explanatory diagram when a cooling part in the fixed base according to the present invention is viewed from above.

FIG. 5 is an explanatory view of a cooling portion of the glass substrate on the fixed base according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Liquid crystal cell, 2 ... Sealant, 3 ... Liquid crystal dish, 4 ... Liquid crystal,
5: Liquid crystal injection port, 6: Upper glass substrate, 7: Lower glass substrate, 8: Lower substrate fixing base, 9: Upper substrate fixing base, 10
... pressure regulating valve, 11 ... vacuum pump, 12 ... cooling part, 1
3 ... heat insulation part, 14 ... cooling part.

Claims (1)

[Claims] A liquid crystal is dropped inside a sealant applied to a peripheral portion of one of two glass substrates, and the other glass substrate is overlaid. In a method of manufacturing a liquid crystal display device in which liquid crystal is injected into a liquid crystal cell, the glass substrate coated with the sealing agent is held on a fixed base in the overlaying apparatus, and a cooling part provided on the fixed base is provided. A method for manufacturing a liquid crystal display device, wherein the two glass substrates are overlapped while cooling the glass substrate surface near the inside of the sealant below a temperature at which the viscosity of the liquid crystal becomes 100 cP or more.