JP2001142041A - Liquid crystal injection device for liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal injection device injecting a liquid crystal from which dissolved gas is eliminated into a liquid crystal display element. SOLUTION: The liquid crystal injection device for a liquid crystal display element is constructed by providing a dissolved gas eliminating device 6 having a gas permeation tube 24 formed with a nonporous membrane composed of resin insoluble in the liquid crystal between a liquid crystal storage vessel for supplying the liquid crystal and the liquid crystal display element so as to degass the liquid crystal before injection.

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 used for injecting a liquid crystal in manufacturing a liquid crystal display device.

[0002]

2. Description of the Related Art A liquid crystal display element is widely known as a device which displays a character or the like by an electro-optic effect by providing a liquid crystal layer in a gap between a pair of glass substrates with electrodes. Such a liquid crystal injection device for a liquid crystal display element is roughly classified into the following three types.

(1) A liquid crystal display device having an inlet,
The liquid crystal dish containing the liquid crystal is put in a vacuum container, and after the vacuum container is evacuated, the inlet is brought into contact with the liquid crystal dish, and the process returns the vacuum container to atmospheric pressure. (Japanese Patent Publication No. 58-49853).

(2) In addition to the inlet of the liquid crystal display element, a method of providing an air outlet for air in the element and injecting liquid crystal from the inlet while sucking and exhausting from the outlet (Japanese Patent Laid-Open No. 9-15)
No. 0010).

(3) A method of directly evacuating a liquid crystal display element and injecting liquid crystal into the element (Japanese Patent Laid-Open No. Hei 10-253975).

Comparing the features of each of the above methods in terms of the structure of the apparatus, (1) requires a vacuum container (bell jar), while (2) and (3) require no vacuum container. is there.

[0007]

In the above-mentioned conventional method for injecting liquid crystal into a liquid crystal display element, in any case, a dissolved gas is contained in the liquid crystal. Therefore, it is necessary to degas dissolved gas in the liquid crystal in the liquid crystal injection step.

In the method (1), since the liquid crystal display element and the liquid crystal are placed together in a vacuum container, bumping of the liquid crystal occurs during vacuum evacuation, and the inside of the vacuum container may be contaminated. Therefore, in order to avoid this bumping, it takes a long time to evacuate, and it takes several hours depending on the type and temperature of the liquid crystal material.

However, exposing the liquid crystal to vacuum for a long time causes evaporation of the liquid crystal. Next, the liquid crystal is exposed to the atmospheric pressure when the liquid crystal is injected into the liquid crystal display element, so that the gas is redissolved in the liquid crystal and causes bubbles of the liquid crystal display element.

In the above methods (2) and (3), since the element to be injected and the liquid crystal are evacuated separately, contamination in the vacuum container due to bumping of the liquid crystal is avoided, and the time required for evacuation is reduced. However, special equipment is required for degassing the liquid crystal, and time is still required for degassing the liquid crystal (for example, about one hour), which is an obstacle to reducing the cost of production equipment and improving productivity.

In view of the above, it is an object of the present invention to provide a liquid crystal injection device for a liquid crystal display device which efficiently removes dissolved gas of the liquid crystal and injects the liquid crystal into the liquid crystal display device.

[0012]

The gist of the present invention for solving the above-mentioned problems is as follows.

[1] A liquid crystal injection device for a liquid crystal display device for producing a liquid crystal display device by injecting a liquid crystal into the liquid crystal display device, wherein a gas permeation tube through which the dissolved gas in the liquid crystal permeates the gas is provided. A liquid crystal injection device for a liquid crystal display device, characterized in that liquid crystal removed from the wall surface of the liquid crystal display device is injected into the liquid crystal display device.

[2] The liquid crystal injection device for a liquid crystal display element, wherein the gas permeable tube is formed of a resin non-porous film that is not eluted by liquid crystal.

[3] The liquid crystal injection device for a liquid crystal display element, wherein the non-porous film is a fluorine-based resin.

[4] The liquid crystal injection device for a liquid crystal display element, wherein the liquid crystal injection device includes a heating unit.

In the above, it is important for the gas permeation tube used for degassing the dissolved gas in the liquid crystal to be one that elutes into the liquid crystal and does not contaminate the liquid crystal. Those composed of a film are most preferred.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the drawings.
FIG. 1 is a schematic sectional view of a dissolved gas removing device of a liquid crystal injection device according to the present invention. A gas transmission tube 24 made of fluororesin is provided as a non-porous film that does not contaminate the liquid crystal and does not transmit the liquid crystal in a system through which the liquid crystal in the dissolved gas removing device 6 in a vacuum state passes. By passing the liquid crystal through the transmission tube, only the dissolved gas in the liquid crystal is depressurized and removed from the tube wall.

By using the gas permeable tube 24, bumping of the liquid crystal does not occur even in the vacuum vessel, and the injection time is shortened. Therefore, evaporation of the liquid crystal can also be suppressed,
The equipment is also much lower in cost than conventional equipment.
Further, the liquid crystal degassing time can be significantly reduced to one hour or less, so that productivity can be improved.

Next, the present invention will be specifically described based on examples.

Embodiment 1 FIG. 2 is a schematic structural view showing an example of a liquid crystal injection device for a liquid crystal display device according to the present invention. The size of the liquid crystal display element 1 used in this embodiment is
0 mm x 200 mm on the short side, and the diagonal length of the display is 1
A transparent glass substrate having a surface of 0.4 inches and a thickness of 1.1 mm was polished.

A common electrode, a signal electrode, a pixel electrode and the like were formed on the substrate, and a liquid crystal alignment film was formed on the outermost surface. In this embodiment, a polyimide alignment film is employed. A polyimide solution was applied to the glass substrate surface using a printing machine, and the thickness of the alignment film after baking was formed to about 0.07 to 0.1 μm.

Thereafter, in order to align the liquid crystal on the surface of the alignment film, an alignment treatment was performed using a rubbing machine having a buff cloth made of rayon on a rubbing roll. The rubbing angle of this liquid crystal display element was 45 degrees with respect to the short side, and was formed so as to be orthogonal between the upper and lower substrates.

For bonding the upper and lower substrates, an appropriate amount of polymer beads was mixed in a sealing agent of an epoxy resin and printed on the substrate using a seal mask. Thereafter, the sealant was temporarily cured, the upper and lower substrates were combined, and while the two substrates were pressed using a press, the sealant was cured to produce a liquid crystal display element.

Further, spherical polymer beads are sandwiched between the upper and lower substrates in the liquid crystal display element, and the gap between the upper and lower substrates is set to be 6.0 μm when the liquid crystal is sealed.

The sealant for the liquid crystal display element was provided around the substrate 1, and a liquid crystal injection port 3 for injecting liquid crystal was provided in a part of the short side. The width of the liquid crystal injection port 3 is 30 mm.

A method of injecting liquid crystal into the liquid crystal display device thus manufactured will be described with reference to FIG. 50 ml of the liquid crystal 2 of ZLI-1132 manufactured by Merck was placed in the liquid crystal storage container 5 having an inner volume of 100 ml with the liquid crystal opening / closing valve 11 closed.

The liquid crystal 2 contains an inert gas (argon gas) in advance to stably store the liquid crystal.
As a result, even when the degassing of the liquid crystal is not complete, only the inert gas is contained in the liquid crystal supplied to the liquid crystal display element, and the long-term stability of the liquid crystal display element, that is, the reliability of the product, Is secured.

Next, the liquid crystal on-off valve 12 is closed, the decompression on-off valve 9 is opened, and the rotary pump of the decompression device 8 is operated. . The degree of vacuum of 1 Pa is maintained until the liquid crystal display element 1 is filled with the liquid crystal 2.

The gas permeable pipe 24 provided in the dissolved gas removing device 6 preferably has an inner diameter of 2 mm or less. If the diameter is equal to or smaller than the inner diameter, the dissolved gas in the liquid crystal 2 is diffused almost instantaneously by passing through the gas permeable tube 24 to remove the dissolved gas.

Further, as shown in FIG. 1, the dissolved gas removing device 6 is provided with a heater 25 for heating the liquid crystal 2, so that the diffusion speed of the dissolved gas can be improved, and the dissolved gas removal rate can be further improved. Can be planned. Further, since the viscosity of the liquid crystal can be reduced, the filling time can be reduced.

Next, after the liquid crystal injection port 3 of the liquid crystal display element 1 is connected to the liquid crystal injection suction cassette 4,
3 and 14 were opened, the rotary pump of the pressure reducing device 8 was operated for 10 minutes, and the pressure inside the liquid crystal display element 1 was reduced to 50 Pa while monitoring with the Pirani vacuum gauge 17.

Next, the pressure reducing valve 13 was closed, the liquid crystal valve 11 was opened, and then the liquid crystal valve 12 was opened.

The liquid crystal 2 in the liquid crystal storage container 5 is subjected to a dissolved gas removal device 6 (here, the dissolved gas in the liquid crystal 2 is degassed) by the pressure difference in the storage container 5 and the pressure in the liquid crystal display element 1.
Then, the liquid crystal from which the dissolved gas has been degassed is injected into the liquid crystal display element 1 via the liquid crystal injection suction cassette 4.

In this embodiment, the time for completely injecting the liquid crystal 2 into the liquid crystal display element 1 (filling time) was 151 minutes, which was almost the same as the conventional method.

After the liquid crystal injection was completed, the liquid crystal opening / closing valve 12 was closed, the liquid crystal display element 1 was separated from the liquid crystal injection suction cassette 4, and the liquid crystal injection port 3 was sealed with an ultraviolet curing agent (acrylic resin). Liquid crystal 2 remaining in liquid crystal filling suction cassette 4
Opened the decompression opening / closing valve 13 and collected the liquid crystal in the liquid crystal collection container 7.

Visual observation and microscopic observation revealed that no air bubbles were observed. In addition, observation under crossed Nicols showed no display unevenness due to the injection step. Further, as a result of disassembling the liquid crystal display element 1 and analyzing the liquid crystal, the liquid crystal composition did not change at all, and the specific resistance of the liquid crystal did not change from before use.

The dissolved gas in the liquid crystal 2 is about 1/5 of 5% by volume of the saturation value of the argon gas previously dissolved in the liquid crystal.
Only 20 was detected, and other gases were hardly detected. According to this embodiment, although it depends on the temperature, the liquid crystal deaeration time is 1/5 to 1/10 as compared with the conventional method.
Can be reduced to

[Embodiment 2] A vacuum vessel (bell jar) 18 capable of controlling pressure reduction is provided, and a liquid crystal display element 1 and a liquid crystal 2 at a certain distance from the liquid crystal display element 1 are provided in the vacuum vessel.
A liquid crystal injection method using a liquid crystal injection device composed of a liquid crystal dish 19 satisfying the above will be described with reference to the schematic configuration diagram of FIG.

First, the liquid crystal display element 1 is set at a predetermined position in the vacuum vessel 18, and the liquid crystal dish 2 filled with the liquid crystal 2 is similarly set.
1 are arranged at a predetermined interval not in contact with the liquid crystal display element 1. The pressure inside the vacuum vessel 18 is reduced by a rotary pump of the pressure reducing device 8 through a pipe connected to the vacuum vessel and a pressure reducing opening / closing valve 21. Similarly, the pressure inside the liquid crystal display element 1 is reduced through the liquid crystal injection port 3.

On the other hand, the liquid crystal 2 on the liquid crystal dish 19 is supplied from the liquid crystal storage container 5 installed outside the vacuum container 18 according to the first embodiment.
In the same manner as described above, the gas is degassed by passing through the dissolved gas removing device 6 and supplied.

When the degree of vacuum is reduced to 1 Pa or less by the Pirani vacuum gauge 23, the liquid crystal dish 19 is brought into contact with the liquid crystal display element 1 by the vertical driving device 20 comprising a motor connected to the outside, and stops in this state. The time required from the start of evacuation was about 50 minutes, which was reduced to about half that of the conventional method, and bumping of the liquid crystal was not observed.

Next, the gas introduction valve 22 is opened, air is flowed little by little through the pipe, and the inside of the vacuum vessel 18 is slowly returned to the atmospheric pressure. The liquid crystal 2 of the liquid crystal dish 21 is the liquid crystal display element 1
The liquid crystal display element 1 is filled by the pressure difference between the liquid crystal display element 1 and the vacuum container 18 whose pressure is reduced from the liquid crystal injection port 3.

After the liquid crystal 2 is sufficiently injected into the liquid crystal display element 1, the inside of the vacuum vessel 8 is completely returned to the atmospheric pressure, and the liquid crystal display element 1 is taken out. Next, the liquid crystal injection port 3 is sealed with an ultraviolet curable resin, and the injection step is completed. The filling time of the liquid crystal was 145 minutes, which was almost the same as the conventional method.

No bubbles were observed visually or by microscopic observation with a microscope. In addition, observation under crossed Nicols showed no display unevenness due to the injection step. Then, as a result of disassembling the liquid crystal display element 1 and analyzing the liquid crystal, the liquid crystal composition did not change at all, and the specific resistance of the liquid crystal did not change from before use.

The dissolved gas in the liquid crystal is about 1/1 of 5% by volume of the saturation value of the argon gas previously dissolved in the liquid crystal.
Other than the detection of No. 4, other gases were hardly detected. Furthermore, the degassing time of the liquid crystal was reduced in the same manner as in Example 1 as compared with the conventional method.

[0047]

According to the present invention, the dissolved gas in the liquid crystal can be sufficiently reduced as compared with the conventional method, so that the generation of bubbles which is a problem in the liquid crystal display element can be suppressed, and the dissolved gas in the liquid crystal can be suppressed. The time required for degassing can be significantly reduced.

Further, since there is no change in the specific resistance of the liquid crystal and there is no concern about contamination of the liquid crystal, it is possible to provide a liquid crystal display element having no display unevenness.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a dissolved gas removing device of a liquid crystal injection device of the present invention.

FIG. 2 is a schematic configuration diagram illustrating an example of a liquid crystal injection device according to the present invention.

FIG. 3 is a schematic configuration diagram showing another example of the liquid crystal injection device of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display element, 2 ... Liquid crystal, 3 ... Liquid crystal injection port, 4 ... Liquid crystal injection suction cassette, 5 ... Liquid crystal storage container, 6 ... Dissolved gas removal device, 7 ... Liquid crystal collection container, 8 ... Decompression device, 9.1
3, 14, 21 ... decompression opening and closing valve, 10 ... gas introduction valve, 11, 12 ... liquid crystal opening and closing valve, 15, 22 ... gas introduction valve, 16, 17, 23 ... Pirani vacuum gauge, 18 ... vacuum vessel, 19 ... liquid crystal Plate, 20: vertical drive, 24: gas permeable tube, 25: heating equipment.

Continued on the front page (72) Inventor Katsumi Kondo 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture F-term in Hitachi Research Laboratory, Hitachi Ltd. F-term (Reference) 2H088 FA02 FA10 FA22 FA30 MA04 MA20 2H089 NA25 NA31 NA34 NA60 QA12 QA16

Claims (4)

[Claims] 1. A liquid crystal injection device for a liquid crystal display device for producing a liquid crystal display device by injecting a liquid crystal into the liquid crystal display device, wherein a dissolved gas in the liquid crystal is passed through a gas permeable tube that transmits the gas. A liquid crystal injection device for a liquid crystal display element, characterized in that liquid crystal removed from the wall surface is injected into the liquid crystal display element. 2. The liquid crystal injection device for a liquid crystal display device according to claim 1, wherein the gas permeable tube is formed of a resin non-porous film that is not eluted by the liquid crystal. 3. The liquid crystal injection device for a liquid crystal display device according to claim 2, wherein the non-porous film is made of a fluorine-based resin. 4. The liquid crystal injection device for a liquid crystal display element according to claim 1, wherein the liquid crystal injection device includes a heating unit.