JPH01137230A - Liquid crystal injecting device - Google Patents

Abstract

PURPOSE:To reduce the composition fluctuation of a liquid crystal and to reduce the variation of a temperature range of the liquid crystal, the fluctuation of a display characteristic of a liquid crystal display element and the deterioration of a response characteristic by providing a wall on the periphery of a liquid crystal reservoir. CONSTITUTION:A liquid crystal reservoir 2 provided with a wall 1 for surrounding the periphery is filled with a liquid crystal, the inside of a tank 5 is pressure-reduced and exhausted from a pressure reducing valve 6, and thereafter, by using a liquid crystal panel supporting tool 4, the injection port of a liquid crystal panel 3 is immersed into the liquid crystal of the crystal liquid reservoir 2 and the liquid crystal panel 3 is impregnated gradually with the liquid crystal. Subsequently, while returning the pressure to the atmospheric pressure by injecting gradually dry gaseous nitrogen and gaseous argon from a gas leading-in valve 7, the liquid crystal is injected to the liquid crystal panel 3.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a liquid crystal injection device for injecting liquid crystal into a liquid crystal panel.

2. Description of the Related Art Various liquid crystal injection methods and liquid crystal injection apparatuses have been proposed. Generally, moisture is adsorbed on the inner surface of an empty liquid crystal panel, and air and moisture are dissolved in the liquid crystal. When the liquid crystal display element is operated, these substances promote electrolysis of the liquid crystal, causing an increase in impurities, generation of bubbles, etc., and causing deterioration of the display characteristics of the liquid crystal display element.

Conventionally, as a method to remove these moisture and air,
A liquid crystal injection device as shown in the schematic diagram of FIG. 2 has been proposed. This is done by removing the air, moisture, etc. dissolved in the liquid crystal filled in the liquid crystal reservoir 2 and the moisture adsorbed on the inner surface of the empty liquid crystal panel 3 while depressurizing and exhausting it from the pressure reducing valve 6 in the tank 5. After that, the injection port of the liquid crystal panel 3 is immersed in the liquid crystal using the liquid crystal panel support 4 to gradually impregnate the liquid crystal into the liquid crystal panel, and dried nitrogen gas, argon gas, etc. are introduced into the tank 5 from the gas introduction valve 7. This is a liquid crystal injection device that fills the liquid crystal panel 3 with liquid crystal by injecting liquid crystal and using the pressure. The method using such a liquid crystal injection device is currently widely used in the manufacturing process of liquid crystal display elements because it has good productivity and can provide highly reliable liquid crystal display elements.

Problems to be Solved by the Invention However, practical liquid crystal materials used in liquid crystal display elements must satisfy various required characteristics, and are not a single component but a mixed material consisting of several different components. Therefore, if the liquid crystal contains highly volatile components, this method evaporates the easily volatile components in the liquid crystal when removing air, moisture, etc. dissolved in the liquid crystal, causing compositional fluctuations in the liquid crystal. happen. As a result, the melting point and clearing point of the liquid crystal rise, and the liquid crystal temperature range changes. In addition, generally due to compositional changes,
Due to increases in the viscosity of liquid crystals and changes in dielectric anisotropy, fluctuations in display characteristics such as the threshold voltage of liquid crystal display elements,
A decrease in response characteristics occurs.

Means for Solving the Problems An element including a liquid crystal reservoir and a wall surrounding a part or all of the periphery of the liquid crystal reservoir is housed inside the tank, and a device capable of reducing the pressure inside the tank and evacuating the tank is provided.

Effect According to the above structure, by providing a wall around the liquid crystal reservoir, when degassing is performed under reduced pressure, the degree of vacuum within the layer or the vapor pressure of the liquid crystal volatilized within the tank can be distributed, and the wall It seems that the liquid crystal is less likely to volatilize than without it. Therefore, compositional fluctuations in the liquid crystal are reduced, and changes in the temperature range of the liquid crystal, fluctuations in display characteristics of the liquid crystal display element, and deterioration in response characteristics can be reduced.

Example FIG. 1 shows a schematic diagram of the liquid crystal injection device of the present invention.

1 is a wall surrounding the liquid crystal reservoir, 2 is a liquid crystal reservoir, 3 is a liquid crystal panel, 4 is a liquid crystal panel support for raising and lowering the liquid crystal, 5
6 indicates a tank, 6 indicates a pressure reducing valve, and 7 indicates a gas introduction valve.

The liquid crystal is placed in a groove in the liquid crystal reservoir 2, which has a surrounding wall l, and
The interior is depressurized and evacuated from the pressure reducing valve 6, and then the injection port of the liquid crystal panel 3 is immersed in the liquid crystal in the liquid crystal reservoir 2 using the liquid crystal panel support 4, so that the liquid crystal panel 3 is gradually impregnated with liquid crystal. Next, liquid crystal is injected into the liquid crystal panel 3 while gradually injecting dry nitrogen gas or argon gas through the gas introduction valve 7 to return the pressure to atmospheric pressure.

The size, shape, position, etc. of the wall l surrounding the liquid crystal reservoir 20 must be optimized in accordance with the shape of the liquid crystal panel, the size, position, etc. of the injection port. For example, it is preferable to reduce the area of the liquid crystal reservoir 2 and provide a wall 1 adjacent to it higher than the liquid crystal surface. Surrounding a portion of the liquid crystal reservoir 20, that is, on three or three sides, with walls 1 has the effect of reducing compositional fluctuations of the liquid crystal compared to the case where the walls 1 are not provided. Also, liquid crystal reservoir 2
It is more effective to surround the entire area, that is, on all four sides, with the wall 1, but it is difficult to bring the injection port of the liquid crystal panel 3 close to the liquid crystal reservoir 2, and it is difficult to close the liquid crystal reservoir 2 by a part or all of the wall 1 surrounding the liquid crystal reservoir 2. It is necessary to remove the tube or use an auxiliary device such as a tube to inject it.

A part of the wall 1 surrounding the liquid crystal reservoir 2, or
When removing the entire tank, a liquid crystal reservoir 2 provided with a surrounding wall 1 is filled with liquid crystal, and the inside of the tank 5 is depressurized and evacuated through a pressure reducing valve 6. After sufficiently depressurizing and exhausting the air, remove part or all of the wall 1 surrounding the product temperature 2, and remove the liquid crystal panel support 4.
The injection port of the liquid crystal panel 3 was immersed in the liquid crystal in the liquid crystal reservoir 2 using a water bottle, and the liquid crystal panel 3 was gradually impregnated with the liquid crystal. Liquid crystal is injected into the liquid crystal panel 3 while gradually injecting dry nitrogen gas or argon gas from the gas introduction valve 7 to return to atmospheric pressure. At this time, an auxiliary tool is required to remove the wall 1.

By providing a heater in the liquid crystal reservoir 2, the viscosity of the liquid crystal is lowered and air and moisture can be easily removed.

Furthermore, by providing the liquid crystal panel support 4 with a heater that can control the temperature of the liquid crystal panel, when injecting liquid crystal into the liquid crystal panel, the viscosity of the liquid crystal can be reduced and the efficiency of liquid crystal injection can be improved. Further, by providing a cooler on the wall l, volatilization of the liquid crystal can be suppressed. When these heaters and coolers are provided, it is necessary to provide a heat insulating material between the wall 1 and the liquid crystal reservoir 2.

Example 1 Liquid crystal A containing volatile components was prepared with the following composition.

The clearing point of this liquid crystal A is 70.0°C.

Injection into liquid crystal was performed as follows using a liquid crystal injection device as shown in FIG. In a tank 5 at 25°C, liquid crystal is poured into a liquid crystal reservoir 2 provided with a surrounding wall 1, and a pressure reducing valve 6 is placed.
After opening, the liquid crystal A was degassed for 10 minutes while the tank 3 was depressurized to 4 Pa and evacuated using a vacuum pump. Using the support 4, the injection port of the liquid crystal panel was immersed in the liquid crystal A in the liquid crystal reservoir 2, and the gas introduction valve 7 was opened and nitrogen gas was gradually injected. While returning to atmospheric pressure, the liquid crystal A was injected into the liquid crystal panel. .At this time, the case where the wall 1 is attached to the night goods storage 2 is all (four sides), three sides are surrounded, and the liquid crystal panels are (1) and (2) respectively.
, and (3) was used.

The clearing point of liquid crystal A after degassing under reduced pressure and the liquid crystal display element (1
Table 1 shows the rise response time when a voltage corresponding to the threshold voltage is applied from a state where no voltage is applied for ) (2×3).

As a comparative example, liquid crystal A was similarly injected into the liquid crystal panel (4) using the liquid crystal injection device shown in FIG.

Table 1 shows the clearing point of liquid crystal A after degassing under reduced pressure and the rise response time when a voltage corresponding to the threshold voltage is applied to the liquid crystal display element (4) from a state where no voltage is applied.

Table 1 (Clearing point of liquid crystal A before depressurization, 70.0°C) As is clear from the above, by using the liquid crystal injection device of the present invention, fluctuations in the composition of the liquid crystal can be reduced and the display characteristics can be reduced. It is possible to manufacture a liquid crystal display element without using a liquid crystal display device.

Example 2 Liquid crystal B containing volatile components was prepared with the following composition.

The clearing point of this liquid crystal B is 63.0°C.

Liquid crystal B was injected as follows using a liquid crystal injector as shown in FIG. In a tank 5 at 24°C, liquid crystal B is placed in a liquid crystal reservoir 2 provided with a wall 1 that surrounds the entire periphery, and the pressure reducing valve 6 is opened. Defoamed for a minute. After depressurizing and evacuating, remove the wall l using the auxiliary tool 8, immerse the injection port of the liquid crystal panel (5) into the liquid crystal B of the liquid crystal reservoir 2 using the support tool 4, and open the gas introduction valve 7 to inject nitrogen gas. Liquid crystal B was injected into the liquid crystal panel (5) while gradually injecting and returning to atmospheric pressure.

The clearing point of liquid crystal B after degassing under reduced pressure and the liquid crystal display element (5
Table 2 shows the rise response time when a voltage corresponding to the threshold voltage is applied from a state where no voltage is applied.

As a comparative example, liquid crystal B was similarly injected into the liquid crystal panel (6) using the liquid crystal injection device shown in FIG.

Table 2 shows the clearing point of liquid crystal B after degassing under reduced pressure and the rise response time when a voltage corresponding to the threshold voltage is applied from a state where no voltage is applied to the liquid crystal display element (6).

Table 2 (Clearing point of liquid crystal B before depressurization, 63.0°C) As is clear from the above, by using the liquid crystal injection device of the present invention, compositional fluctuations in liquid crystal can be reduced and display characteristics can be maintained without deterioration. Can you make a liquid crystal display element?

Example 3 Liquid crystal C containing volatile components was prepared with the following composition.

(The following is a blank space) Liquid crystal C was injected as follows using a liquid crystal injector as shown in FIG. In a tank 5 at 28°C, liquid crystal C is placed in a liquid crystal reservoir 2 with a wall 1 surrounding it on three sides, and the pressure reducing valve 6 is opened. Defoamed for a minute. Using the support 4, immerse the injection port of the liquid crystal panel (7) into the liquid crystal C of the liquid crystal reservoir 2, and open the gas introduction valve 7 to gradually inject nitrogen gas and return it to atmospheric pressure. Liquid crystal C was injected.

Table 3 shows the results of analyzing the composition of the liquid crystal C after degassing under reduced pressure using gas chromatography.

The rise response time when a voltage corresponding to the threshold voltage was applied from a state where no voltage was applied to the liquid crystal display element (7) was 120 m5.

As a comparative example, using the liquid crystal injection device shown in Fig. 2, 7α
Liquid crystal C was similarly injected into the product panel (8).

Table 3 shows the results of analyzing the composition of liquid crystal C after degassing under reduced pressure using gas chromatography.

The rise response time when a voltage corresponding to the threshold voltage was applied from a state where no voltage was applied to the liquid crystal display element (8) was 168 m5.

(Space below) Table 3 Results of Mi composition analysis (wtχ) As is clear from the above, by using the liquid crystal injection device of the present invention, composition fluctuations in liquid crystal can be reduced and liquid crystal display elements can be improved without deteriorating display characteristics. It can be made.

Effects of the Invention The liquid crystal injection device of the present invention is effective for liquid crystals containing volatile components, reduces compositional fluctuations in liquid crystals, and eliminates deterioration and variation in display and response characteristics of liquid crystal display elements. Further, the present invention can provide a liquid crystal display element with good productivity and high reliability, and has very high practical value.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a liquid crystal injection device according to an embodiment of the present invention, Fig. 2
The figure is a schematic diagram of a liquid crystal injection device of a conventional example, and FIG. 3 is a schematic diagram of a liquid crystal injection device of another embodiment of the present invention. 3...Liquid crystal panel, 4...Liquid crystal panel support for raising and lowering the liquid crystal, 5...tank, 6...pressure reducing valve, 7...gas introduction valve, 8... Auxiliary tool for removing walls. Name of agent: Patent attorney Toshio Nakao (1 person) Figure 1 Figure 2

Claims (5)

[Claims] (1) An element including a liquid crystal reservoir and a wall surrounding part or all of the periphery of the liquid crystal reservoir is housed inside the tank, and a device is provided that can reduce the pressure and exhaust the inside of the tank. Liquid crystal injection device. (2) Claim 1, characterized in that the wall surrounding part or all of the liquid crystal reservoir is removable.
Liquid crystal injection device as described in section. (3) The liquid crystal injection device according to claim 1, wherein the liquid crystal reservoir is provided with a heater capable of controlling the temperature of the liquid crystal. (4) The liquid crystal injection device according to claim 1, characterized in that a heater whose temperature can be controlled is provided on the wall. (5) The liquid crystal injection device according to claim 1, characterized in that a heat insulating material is provided between the liquid crystal reservoir and the wall.