JPH1020315A - Method for injecting liquid crystal to liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the liquid crystal injection time which affects mass productivity and to prevent the air bubbles and the unequal thicknesses of liquid crystal layers which affect image quality and the change of a liquid crystal compsn. which affects optical characteristics. SOLUTION: Liquid crystals are injected into liquid crystal elements 4 having spacings between two substrates in this method. The liquid crystal elements 4 provided with at least one piece of injection ports in the liquid crystal elements 4 and a liquid crystal tray 1 in which the liquid crystals are contained are put into an evacuatable vessel 6. The injection ports of the liquid crystal elements 4 are immersed into the liquid crystals in the liquid crystal tray 1 in the state of discharging the air from the inside of the vacuum vessel 6 and thereafter, the atm. pressure is restored in the vacuum vessel 6 to inject the liquid crystals into the spacings of the liquid crystal elements 4. At this time, the liquid crystal tray 1 is heated and the warmed liquid crystals are injected into the spacings of the liquid crystal elements 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for injecting liquid crystal into a liquid crystal element of a liquid crystal display.

[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, and the like 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) A method in which liquid crystal is dropped on one glass substrate, and another glass substrate is overlaid on the glass substrate via an electrically insulating spacer such as polyethylene beads or silica beads (Japanese Patent Laid-Open No. -285910).

(2) In a liquid crystal element having a gap between two glass substrates in advance, a hole is formed outside the injection port to communicate with a position opposite to the injection port, and the liquid crystal is dropped into the injection port to utilize the capillary phenomenon. how to.

(3) A method in which a liquid crystal element configuration similar to that of (2) is employed, the injection port is immersed in liquid crystal, and vacuum is drawn from one port to suck up the liquid crystal (Japanese Patent Laid-Open No. 7-281200).

(4) A liquid crystal element provided with an injection port and a liquid crystal dish containing liquid crystal are placed in an exhaust system container, the exhaust system container is evacuated, and then the injection port is immersed in the liquid crystal to enlarge the exhaust system container. A method using a pressure difference in the process of returning to atmospheric pressure (Japanese Patent Publication No. 58-49853).

(5) A method of heating the exhaust system container and the liquid crystal element according to the method of (4) (JP-A-5-289037)

[0008]

The above-described conventional liquid crystal injection method for a liquid crystal display device has the following disadvantages.

That is, in the method (1), it is difficult to adjust the amount of liquid crystal, and air bubbles tend to remain. In addition, there are many problems that a sealant for preventing the liquid crystal from leaking outside contaminates the liquid crystal.
In the method (2) utilizing the capillary phenomenon, when the screen size is large, the liquid crystal is not uniformly distributed, and bubbles are easily generated. The method (3) is suitable for uniformly filling the liquid crystal in the liquid crystal element and is an effective means for shortening the injection time. However, since dissolved air is not excluded, bubbles are generated after several days. I am worried. Further, when vacuum is applied, the spacer for keeping the gap between the two substrates uniform moves, which causes unevenness of the gap and traces of movement of the spacer, thereby significantly deteriorating the display quality. The method (4) is generally used because it is suitable for uniformly introducing the liquid crystal into the liquid crystal element, and the dissolved air in the liquid crystal is removed and there is no fear of bubbles. However, since the injection time is long, large-sized liquid crystal elements lack mass productivity.
The method (5) compensates for the disadvantage of (4) that the injection time is long. However, even if the exhaust system container is heated, a temperature difference occurs in the liquid crystal element itself depending on the position of the liquid crystal element, and the injection time differs. . In addition, for heating a liquid crystal element, one element must be provided with a heating mechanism. Heating the exhaust system container and the liquid crystal element is not suitable for mass production.

[0010]

In order to solve the above-mentioned problems, as a means, in a process of injecting a liquid crystal into a liquid crystal element having a gap between two substrates, at least one note is injected into the liquid crystal element. The liquid crystal element provided with the inlet and the liquid crystal dish containing the liquid crystal are placed in a container capable of vacuuming, and while the air in the vacuum vessel is exhausted, the injection port of the liquid crystal element is immersed in the liquid crystal in the liquid crystal dish. After that, in the liquid crystal display device in which the inside of the vacuum vessel is returned to the atmospheric pressure and the liquid crystal is injected into the gap between the liquid crystal elements, the liquid crystal heated by heating the liquid crystal dish is injected into the gap between the liquid crystal elements. A liquid crystal injection method for a liquid crystal display device, comprising:

It has been found that heating the liquid crystal dish is the most effective way to reduce the viscosity of the liquid crystal in order to inject the liquid crystal in a short time without bubbles in the liquid crystal element. When the method of the present invention is used, there is no temperature variation between liquid crystal elements, the equipment is simple, and it is possible to contribute to mass productivity.

[0012]

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

FIG. 1 shows an injection method for a liquid crystal display device according to the present invention. That is, the liquid crystal element 4 is placed in the vacuum container 6.
Are set uniformly with the liquid crystal injection port 16 (FIG. 4) facing down. At an appropriate interval below the liquid crystal element 4, the surface of the liquid crystal dish 1 is coated with Teflon, and the liquid crystal 2 is provided so as to be higher than the surface of the liquid crystal dish 1 due to the surface tension of Teflon. The amount of the liquid crystal 2 is sufficient for the injection amount required for the liquid crystal element 4. As for the liquid crystal 2, the heater 3 in the liquid crystal dish 1 is connected to the external power supply 8 and the temperature controller 7,
The temperature of the liquid crystal 2 can be set arbitrarily.
The liquid crystal dish 1 is connected to an elevator 5 so that the liquid crystal tray 1 can be moved up and down as indicated by an arrow. The inside of the vacuum vessel 6 can be evacuated and vented by a rotary pump 10 and a pressure regulating valve 9.

Although the individual liquid crystal display devices have been described above, they will be described in more detail. Vacuum 5 × 10 ~ ³ Pa in the inside of the vacuum container 6 rotary pump 10 and the pressure regulating valve 9
After that, the ZLI-1132 liquid crystal {NI point (temperature at which the liquid crystal becomes an isotropic liquid) 71 ° C.} 2
Temperature to 40 ° C and the liquid crystal tray 1
Immerse in an inch size liquid crystal element (seven pieces) 4. After 1-2 minutes, the rotary pump 10 is stopped, and the inside of the vacuum vessel 6 is gradually returned to the atmosphere by the pressure regulating valve 9. In the process of returning to the atmospheric pressure, the injection state of the liquid crystal element 4 in the front row (FIG. 3) is observed from a viewing window through which the inside of the pressure vessel 6 can be observed.

After the filling of the entire 10.4 inch is completed, the liquid crystal dish 1 is lowered by the elevator 5 to separate the liquid crystal 2 from the liquid crystal element 4. Since the inside of the vacuum container 6 has returned to the atmospheric pressure before the completion of the liquid crystal injection, the liquid crystal element 4 is immediately taken out of the vacuum container 6 and the injection port is closed using an ultraviolet curing resin.
The liquid crystal 2 may be warmed before the vacuum container 6 is evacuated or at the same time as the evacuation. Although the upper limit of the temperature of the liquid crystal may be any number of times, there are problems such as a change in the liquid crystal composition and a long time until warming, and a temperature almost half of the NI point gives good results in experiments and the like. It has gained.

FIG. 2 shows a heating type liquid crystal dish 1 according to the present invention.
The liquid crystal dish 1 is substantially halved in the thickness direction, and a rubber heater 11 is connected to the outside by a lead wire 12 at a lower portion (b). The alignment pin 13 is passed through the alignment hole 14 in the upper part (a) to be integrated vertically. The liquid crystal dish 1 in the upper part (a) is coated with Teflon, and the liquid crystal 2 does not leak from the liquid crystal dish 1 due to surface tension. A hole for inserting a thermocouple 15 is provided substantially at the center of the liquid crystal dish 1 so as to detect the temperature of the liquid crystal 2.

According to the present invention, the liquid crystal heated to 40 ° C. is immersed in the liquid crystal element, and the time from the completion of the injection to the separation of the liquid crystal from the liquid crystal element (injection time) is 50 minutes. Since there were no bubbles and there was no variation in temperature between the liquid crystal elements, the injection time did not differ. From the analysis results, there was no change in the liquid crystal composition, and there was no adverse effect on the optical characteristics.

(Comparative Example) In FIG. 4, instead of warming the liquid crystal dish 1, a thermocouple 15 is attached to the element in the middle of the liquid crystal element 4 by using an infrared lamp 18 from outside the vacuum vessel 6, and this element has a temperature of 40. C., and the liquid crystal 2 was injected into the liquid crystal element 4 in the same manner as in Example 1. The injection time varied among liquid crystal elements, and it took 45 minutes for the first liquid crystal element hit by the infrared lamp and 90 minutes for the seventh liquid crystal element in the last row. The heating time required for the liquid crystal element to reach 40 ° C. was three times longer than that in Example 1.

[0019]

According to the method for injecting liquid crystal of the liquid crystal display device of the present invention, there is no variation between liquid crystal elements, the injection time can be reduced uniformly, and the image quality does not have an uneven thickness of the liquid crystal layer due to the movement of bubbles or spacers. A liquid crystal element with good performance is possible.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a liquid crystal injection method for a liquid crystal display device of the present invention.

FIG. 2 is an explanatory diagram of a liquid crystal dish according to the heating method of the present invention.

FIG. 3 is a state diagram of liquid crystal injected into a liquid crystal element.

FIG. 4 is an explanatory diagram of a comparative example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Liquid crystal dish, 2 ... Liquid crystal, 3 ... Heater, 4 ... Liquid crystal element, 5
... Elevator, 6 ... Vacuum container, 7 ... Temperature controller, 8 ...
AC power supply, 9 ... pressure regulating valve, 10 ... vacuum pump, 11 ...
Rubber heater, 12 lead wire, 13 mating pin, 1
4 ... matching hole, 15 ... thermocouple, 16 ... inlet, 17 ... seal, 18 ... infrared lamp.

Claims (1)

[Claims] In the process of injecting a liquid crystal into a liquid crystal element having a gap between two substrates, a liquid crystal element having at least one injection port in the liquid crystal element and a liquid crystal dish containing the liquid crystal are separated. In a vacuum-capable container, the inlet of the liquid crystal element is immersed in the liquid crystal in the liquid crystal dish while the air in the vacuum container is evacuated, and then the inside of the vacuum container is returned to atmospheric pressure and the liquid crystal is removed. A liquid crystal display device for injecting liquid crystal into a gap between elements, wherein a liquid crystal heated by heating the liquid crystal dish is injected into the gap between the liquid crystal elements.