JP2003156753A - Liquid crystal injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for manufacturing a liquid crystal display device wherein no bubble is generated, time for a reduced pressure treatment stage can be reduced, a volatile liquid crystal material can be used and no dropping trace is generated in the manufacture of a liquid crystal display device by a dropping device. SOLUTION: A dehydration device is provided between a liquid crystal storage container and a liquid crystal dropping tool.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal injection device.

[0002]

2. Description of the Related Art A liquid crystal display device has a liquid crystal layer provided between two glass substrates and has letters, numbers, figures,
It is already known as a device for displaying pictures and the like. Current,
TN (Twisted Nematic), STN (Supertwisted Nemati
c), FLC (Ferroelectric LiquidCrystal), IPS (In-P
Driving modes such as lane switching) are known. There are several known methods for injecting liquid crystal into such a liquid crystal display device. (1) Two glass substrates are pasted together with a sealant, a part of the sealant is released, and a liquid crystal cell provided with a liquid crystal inlet and a liquid crystal dish containing liquid crystal are put into a container capable of vacuuming, and this container After evacuating, the liquid crystal injection port is immersed in the liquid crystal, the container is returned to atmospheric pressure, and the liquid crystal is injected by utilizing the pressure difference between the inside and outside of the liquid crystal cell. (2) Two glass substrates are pasted together with a sealant, two or more places of the sealant are released, one liquid crystal injection port and one or more exhaust ports are provided, and a liquid crystal injection connector is connected to the injection port. And a liquid crystal injection device for injecting liquid crystal (JP-A-7-
281200). (3) A manufacturing apparatus in which liquid crystal is dropped inside a sealant formed on one glass substrate and another glass substrate is bonded in a vacuum container (Japanese Patent Laid-Open No. 63-17932).
No. 3). This liquid crystal injection device is called a dropping device.

Among the liquid crystal injecting devices of these liquid crystal display devices, in the liquid crystal injecting devices of (1) and (2), the time required for injecting the liquid crystal depends on the screen size. It has a lack of problems. In addition, since there is a liquid crystal injection port, it is necessary to perform a process of sealing the injection port after injection of the liquid crystal with an ultraviolet curable resin or the like. In addition, air bubbles from the sealing part or contamination of the liquid crystal by the sealing material may occur. It's a problem. On the contrary,
In the dropping device of (3), the time required for liquid crystal injection is (1)
It is considered to be promising as a manufacturing apparatus for a large-sized liquid crystal display device, which is shorter than the method (2) and hardly depends on the screen size, and thus demand is expected to increase in the future. Further, since there is no injection port, the sealing process is unnecessary.

[0004]

[Problems to be Solved by the Invention] However, (3)
The manufacturing of the liquid crystal display device by the dropping device has the following drawbacks. In the dropping device, the gas remaining in the liquid crystal cell causes bubbles in the step of bonding the two glass substrates together, so that the degree of vacuum in the vacuum container must be increased. Therefore, there is a drawback that the productivity is not improved because the time of this pressure reduction treatment step becomes as long as 30 minutes. Further, since the liquid crystal material is exposed to a high vacuum, the use of a volatile liquid crystal material causes a change in the composition, which results in deterioration of display characteristics. Further, due to the water contained in the liquid crystal, the drop marks of the dropped liquid crystal remarkably deteriorated the display quality.

An object of the present invention is to manufacture a liquid crystal display device using a dropping device, which does not cause bubbles, shortens the time required for the depressurization process, uses a volatile liquid crystal material, and has no dropping mark. To provide a manufacturing apparatus.

[0006]

In order to achieve the above-mentioned object, the present invention is directed to dropping a liquid crystal inside a sealant applied to the peripheral portion on one glass substrate, and then to the other glass in a vacuum container. In a manufacturing apparatus of a liquid crystal display device in which substrates are bonded and liquid crystal is injected into a liquid crystal cell, a dehydrating device for removing water in the liquid crystal is provided between the liquid crystal storage container and the liquid crystal dropping jig. The dehydrator is characterized in that a liquid crystal is bubbled with an adsorbent that adsorbs water and an inert gas.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) An embodiment of a method for manufacturing a liquid crystal display device according to the present invention will be described.

For the production of the liquid crystal display element, a transparent glass substrate having a surface of 270 mm (long piece side) × 200 mm (short piece side) and a thickness of 1.1 mm was used.

A signal electrode, a pixel electrode, etc. are formed on a glass substrate to be the lower substrate 2, and light is mixed with a proper amount of spacer beads having an outer diameter of 6 μm so that the liquid crystal 4 does not leak to the lower substrate 2. The curable resin sealant 3 was printed in a frame shape with a seal mask. In this embodiment, polyimide is adopted as the alignment film, and the film thickness after coating and baking with a printing machine is 0.1.
It was about μm. After that, the alignment film surface was subjected to alignment treatment for liquid crystal alignment. Alignment treatment uses a rubbing machine,
A buff cloth made of rayon was used for the rubbing roll. The display part of this liquid crystal cell is diagonally about 10 inches in size (200 mm x
150 mm).

A common electrode was formed on the other glass substrate to be the upper substrate 1, and stripe-shaped color filters of three colors of red, blue and green and a black matrix were provided. Protrusion spacers for holding the gap between the glass substrates were formed on the color filter with a photocurable resin. Furthermore, an alignment film similar to that of the lower substrate 2 was applied, and a rubbing treatment was performed under the same conditions. The upper substrate 1 was previously subjected to a high temperature annealing treatment in order to prevent gas generation after the liquid crystal display element was manufactured.

Next, the liquid crystal injection device by the dropping method will be described in detail with reference to FIG.

The liquid crystal 4 stored in the liquid crystal storage container 7 usually has a dissolved gas of 100 ppm and a water content of 100 to 200 p.
pm included. The liquid crystal 4 is provided with a dehydrator 6 in the conduit connected to the liquid crystal storage container 7 and the dropping jig 5,
It is guided to the liquid crystal dropping jig 5 through the dehydrating device 6. The dehydrator 6 of FIG. 2 will be described. The dehydrator 6 contains an adsorbent 8 containing a molecular sieve that absorbs water in a container whose outer skin is covered with a hole of several microns. Also,
At the bottom of the dehydrating device 6, there is a vent 9 for bubbling the liquid crystal 4 by blowing nitrogen of an inert gas into the dehydrated liquid crystal 4, and in the upper space, the dissolved gas in the liquid crystal 4 degassed by bubbling. An exhaust port 10 is provided for exhausting the water with a pump (not shown). Dehydration in this way,
The degassed liquid crystal 4 is stored in the liquid crystal dropping jig 5. This dehydrator can be removed, the adsorbent 8 can be replaced,
The deterioration of the adsorbent 8 can be prevented.

On the other hand, below the liquid crystal dropping jig 5, a lower substrate 2 provided with a photo-curing resin sealant 3 in a frame shape is provided. The required amount of the liquid crystal 4 is dropped inside the sealant 3 from the liquid crystal dropping jig 5. Although the dispenser device is used as the liquid crystal dropping device, an inkjet device or the like may be used.

Next, the lower substrate 2 and the upper substrate 1 on which the liquid crystal 4 has been dropped are vacuum containers 11, and the degree of vacuum is 100 Pa (preferably 10 Pa) that does not affect the volatilization of the liquid crystal 4, and the dissolved gas of the liquid crystal 4 is degassed. Then stack them. At this time, the degree of vacuum is 1
The time to reach 00 Pa was 5 minutes, and the decompression time could be shortened significantly. After that, UV is irradiated to cure the sealant 3 to manufacture a liquid crystal display element. When observing this liquid crystal display element, generation of bubbles due to dissolved gas is not found. Further, as shown in FIG. 4, no trace of adsorption of water contained in the liquid crystal 4 on the surface of the alignment film, that is, a trace 12 of dropping was observed. When the dropped liquid crystal 4 was analyzed for water by the Karl Fischer method, the concentration was 10 ppm or less. Further, when analyzed by gas chromatography, there was no change in the composition of the liquid crystal. (Comparative Example) A liquid crystal dropping injection device according to a conventional method in which the dehydrating device 6 is not provided between the liquid crystal storage container 7 and the liquid crystal dropping device 5 will be described in detail with reference to FIG.

The liquid crystal 4 stored in the liquid crystal storage container 7 is guided to the liquid crystal dropping device 5 through a conduit connected to the liquid crystal storage container 7 and the liquid crystal dropping device 5. On the other hand, below the liquid crystal dropping device 5, a lower substrate 2 provided with a photo-curable resin sealant 3 in a frame shape is provided. The required amount of liquid crystal 4 is dropped inside the sealant 3 from the liquid crystal dropping device 5.

Next, the lower substrate 2 and the upper substrate 1 onto which the liquid crystal 4 has been dropped are vacuum containers 11, and the degree of vacuum is 100 Pa (preferably 10 Pa) that does not affect the volatilization of the liquid crystal 4, and the dissolved gas of the liquid crystal 4 is degassed. Then stack them. At this time, the degree of vacuum is 1
The time to reach 00Pa was 30 minutes. The reason why the pressure reduction time could not be shortened as compared with Example 1 is considered to be the influence of water contained in the liquid crystal. After that, UV is irradiated to cure the sealant 3 to manufacture a liquid crystal display element. When this liquid crystal display element is observed, no bubbles are generated due to the dissolved gas, but adsorption traces on the surface of the alignment film due to water contained in the liquid crystal 4 as shown in FIG.
The display quality was significantly impaired. When the dropped liquid crystal 4 was analyzed by gas chromatography, there was no dissolved gas, but when water was analyzed by the Karl Fischer method, 6
The concentration was 0 ppm.

[0017]

According to the manufacturing apparatus of the liquid crystal display device by the dropping device of the present invention, there is no trace of dropping by water. Further, there are no bubbles, the decompression time can be shortened, and the deterioration of display characteristics can be eliminated.

[Brief description of drawings]

FIG. 1 is a schematic view for explaining a liquid crystal dropping injection device device according to the present invention.

FIG. 2 is a schematic diagram for explaining a dehydrator according to the present invention.

FIG. 3 is a schematic view for explaining a conventional liquid crystal dropping injection device.

FIG. 4 is a schematic diagram for explaining a drop mark caused by water by a conventional method.

[Explanation of symbols]

1 ... Upper substrate, 2 ... Lower substrate, 3 ... Sealant, 4 ... Liquid crystal, 5
... Liquid crystal dropping jig, 6 ... Dehydrator, 7 ... Liquid crystal storage container, 8
... Adsorbent, 9 ... Vent, 10 ... Exhaust, 11 ... Vacuum container, 12 ... Drip mark, 13 ... Vacuum pump.

Claims (3)

[Claims] 1. A liquid crystal storage container and a liquid crystal dripping jig are connected, and the liquid crystal dripping jig drips liquid crystal inside a sealant applied to a peripheral portion on one of the glass substrates, and then, in a vacuum container. 2. A device for injecting liquid crystal into a liquid crystal display device by adhering the other glass substrate, wherein a dehydrator for removing water in the liquid crystal is provided between the liquid crystal storage container and the liquid crystal dropping jig. A liquid crystal injection device characterized by the above. 2. The liquid crystal injection device according to claim 1, further comprising an adsorbent for adsorbing water. 3. The dehydrator according to claim 1, wherein a pipe for supplying an inert gas is provided, and the pipe is provided at a position for bubbling the liquid crystal with the inert gas passing through the pipe. Characteristic liquid crystal injection device.