JPS6068323A - Liquid crystal injection method for liquid crystal display device - Google Patents

Abstract

PURPOSE:To prevent the properties of liquid crystal from deteriorating, to prolong its life, and to prevent an air bubble from being dissolved present in a display device and harmful air from being discharging even dissolved air in liquid crystal in the discharge process of an enclosure for containing the liquid crystal. CONSTITUTION:Plural liquid crystal enclosure 1 which has fine gaps for injecting liquid crystals 3 and each have one injection hole formed on the gap of a sealant at the thin gap circumferential edge, and a liquid crystal container 4 containing the liquid crystal 3 are put in an airtight pressure-proof container 5. While the container 4 is evacuated, the enclosure 1 is moved to dip the injection holes of the enclosure 1 in the liquid crystal 3 in the container 4 while plate surfaces are held perpendicular to the surface of the liquid crystal, and the container 5 is released from the pressure reduction state to inject the liquid crystal 3 into the thin gaps of the enclosure 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid crystal injection method for injecting liquid crystal into an envelope of a sandwich cell structure of a liquid crystal display device.

A liquid crystal display device consists of two conductive plates arranged in two rows.
.

It is already known as a device that displays characters, numbers, and other arbitrary patterns by sandwiching a thin layer of liquid crystal between them and using the electro-optic effect.

As a method for injecting liquid crystal into such a liquid crystal display device, several methods shown below are conventionally known.

(1) A method in which liquid crystal is dropped onto one glass plate, and then another glass plate is placed on top of that via an electrically insulating spacer to create a sandwich-type cell structure.

(2) In an envelope that has a sandwich cell structure in advance,
A method of providing two or more through holes that communicate with the gap between the plates and injecting through at least one of them using capillary action.

(3) A method in which liquid crystal is injected while heating the airtight container into which the liquid crystal is injected and evacuating the inside.

(4) Connect the liquid crystal envelope and the container containing the liquid crystal to an exhaust system to evacuate the liquid crystal envelope and eliminate the dissolved air in the liquid crystal in the container, and then remove the liquid crystal in the container. A method of injecting gas under pressure into the liquid crystal outer envelope.

However, the conventional liquid crystal injection method for a liquid crystal display device as described above has the following drawbacks.

In other words, method (1) requires complicated work to sandwich the liquid crystal in a container with a sandwich-shaped cell structure so that no air bubbles remain, and even if it is possible to implement it experimentally, it is difficult to implement industrially. It is unsuitable for implementation.

The remaining air bubbles not only spoil the appearance of the display device but also significantly shorten its driving life. Utilizes capillary action. (
Method 2) is very difficult to inject into a long and narrow sandwich type cell, and especially in display devices in which the electrode material is provided on the glass plate surface, the glass surface and the electrode material are not the same as the liquid crystal. Because the adhesive forces of the two are different, the liquid crystal does not fit uniformly, and air bubbles tend to remain. Method (3) is suitable for uniformly placing the liquid crystal in the envelope, but has the disadvantage that the liquid crystal itself comes into contact with the outside air and at the same time, it is not possible to exclude air dissolved in the liquid crystal. Method (4) is suitable for uniformly placing the liquid crystal in the envelope, and at the same time takes into account the elimination of dissolved air in the liquid crystal, but the process is complicated and there are problems with workability, and mass production Not suitable for

The present invention aims to provide a liquid crystal injection method that is excellent in workability, mass production, and uniformity.

That is, the present invention places a liquid crystal storage container containing liquid crystal at the bottom in a pressure-resistant container equipped with an exhaust system, an intake system, and a means for controlling the movement of objects inside from the outside, and for example, places a liquid crystal reservoir container containing liquid crystal at the bottom, and places a liquid crystal storage container on the top thereof that can be controlled from the outside. With a plurality of airtight liquid crystal envelopes each having at least one injection hole formed in the gap between the sealant around the slit being installed on the rotating shaft, the air in the pressure-resistant container is evacuated. At the same time, after removing the air inside the liquid crystal envelope and the dissolved air in the liquid crystal, move the envelope so that its plate surface is almost perpendicular to the liquid crystal surface and insert the injection hole in the envelope. The method is characterized in that the liquid crystal is injected under pressure into the envelope by immersing the part in the liquid crystal, returning the reduced pressure state of the pressure-resistant container to atmospheric pressure, and heating the envelope. be.

The present invention does not transfer liquid crystal using the difference in pressure applied to the liquid crystal surface in the transfer tube, but the method of the present invention
By means of externally controlled means provided in the pressure-resistant container, multiple envelopes having injection holes formed in the gaps between the sealants are moved to inject the liquid crystal with the plate surface almost perpendicular to the liquid crystal surface. The point is that when the liquid crystal is immersed in the container and the liquid surface of the liquid crystal is pressurized, the liquid crystal is transferred into the envelope.

In the present invention, dissolved air in the liquid crystal can be removed during the evacuation process, so deterioration of the liquid crystal can be prevented over a long period of time, and there is no need for any extra conduit for external injection. In particular, for devices with a narrow display area such as wristwatch display devices, if injection holes are provided on the display surface of the envelope, a sealant should be applied to the edges to avoid damaging the appearance of the display surface. An injection hole consisting of a gap can be provided, and there is no need to provide any extra conduit for injection externally, resulting in extremely good workability. In addition, it is possible to install a large number of liquid crystal envelopes with a sandwich-type cell structure vertically and inject the liquid crystal from the side surface of the spring while heating it, making it possible to manufacture a large number of liquid crystal display devices in a small area. One embodiment of the present invention will be described in detail below.

FIG. 1 shows a schematic configuration of the basic parts of an apparatus for carrying out the method of the present invention. Reference numeral 1 denotes a liquid crystal envelope to which electrodes have been attached, and two glass plates are held parallel to each other by spacers.

This envelope 1 can be accessed from the outside of the pressure container 6 by, for example, a pusher 6.
The container is suspended from a rotating shaft 7 that can be controlled by a rotary shaft 7, and is arranged so that the injection hole 2 is located at the bottom of the envelope. A liquid crystal reservoir container 4 containing a liquid crystal 3 is placed at the bottom of the pressure container 6. This pressure-resistant container 6 is connected to an exhaust system via a pulp 8,
This allows air to be taken in through valve 9.

In the above configuration, first, the valve 8 is opened to operate the exhaust system, and the pressure vessel 6 and the envelope 1 are evacuated. As a result, the inside of the envelope 1 becomes a vacuum state, and the air dissolved in the liquid crystal 3 in the liquid crystal reservoir can also be removed. After sufficient evacuation, the pulp 8 is closed and the handle 6 is rotated to move the suspended envelope 1 downward so that the injection hole 2 is immersed in the liquid crystal 3. After the liquid crystal sufficiently covers the injection hole 2, the pulp 9 is opened. Air flows into the pressure container 6 which is in a vacuum state and pressurizes the liquid surface of the liquid crystal 3 1-1. Due to the breakage, the liquid crystal flows into the envelope 1 and spreads uniformly between the glass plates.

After the liquid crystal injection is completed in this way, the pressure container is removed and the next envelope is installed. Repeat this operation below.

FIG. 2 is a diagram for explaining an example of the position of the injection hole of the envelope used in the present invention. The injection hole does not need to be made through the display surface using a punching machine, and the periphery of the gap in the envelope should be filled with a sealant such as flint glass or epoxy adhesive.
It is formed by providing a gap in the center part 11 or the tip part 12 of one end of the envelope so that the gap between the plates and the outside communicate with each other when sealing is performed. With this structure, there is no need to provide an injection member outside the envelope. FIG. 1 is a conceptual diagram of an embodiment of the present invention shown in FIG. This heating mechanism lowers the viscosity of the liquid crystal, allowing it to be quickly injected and evenly spread between the plates. In FIG. 3, 13 is an envelope, 14 is a heating element, 1F5 is a suspension string, and 16 is an injection port.

Furthermore, if a large number of liquid crystal display devices are to be manufactured at the same time, this can be achieved by installing a large number of liquid crystal envelopes so that their plate surfaces are substantially perpendicular to the liquid crystal surface. FIG. 4 shows the configuration of this device. In FIG. 4, reference numeral 17 denotes an airtight pressure-resistant container, in which, for example, a large number of envelopes 18 are suspended from a rotating shaft 19. Handle 20
Its movement is controlled by.

As described above, according to the method of the present invention, dissolved air in the liquid crystal is also removed in the process of exhausting the envelope for sealing the liquid crystal, so that no air bubbles are present in the liquid crystal display device. It is also possible to prevent harmful air from dissolving.

This makes it possible to prevent the deterioration of the characteristics of liquid crystal display devices, especially the liquid crystal that has been the most problematic for practical use, and to extend the life of the display device. Since an injection hole can be provided in the liquid crystal display, it is particularly suitable for liquid crystal injection with a narrow display area such as a display device of a wristwatch.

In addition, since the plate surfaces of the plurality of envelopes are arranged substantially perpendicular to the liquid crystal surface, a large number of liquid crystal display devices can be manufactured simultaneously in a small area, making it extremely suitable for mass production.

Furthermore, according to the present invention, the injection hole is formed in the gap between the sealant around the periphery of the envelope, and there is no need for any extra external mechanism for injection, further improving mass productivity. Because the liquid crystal is injected into the container, it is possible to inject uniformly and quickly.

In addition, since the liquid crystal only comes into contact with the gap and the vicinity of the encapsulant in the envelope during injection, the liquid crystal may adhere to other parts of the envelope, causing loss of liquid crystal, or the liquid crystal and the outer part may be damaged. There is no possibility of dirt on the container.

10 Heno

[Brief explanation of the drawing]

Fig. 1 is a basic schematic configuration diagram of an apparatus for implementing the method of the present invention, Fig. 2 a and b are respectively front views of the envelope, and Figs. 3 and 4 are respectively for implementing the method of the present invention. FIG. 2 is a schematic configuration diagram of the device. 1.13.18...Liquid crystal envelope, 2,11,1
2゜16...Injection hole, 3...Liquid crystal, 4
...Liquid crystal container, 6...Pressure container,
14... Heating body. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figures (a-) (b) Figure 4/q 11

Claims (1)

[Claims] A plurality of liquid crystal envelopes each having a slit into which the liquid crystal is injected and at least one injection hole formed in a gap of the sealant around the slit, and a liquid crystal reservoir containing the liquid crystal. Place the liquid crystal envelope in an airtight pressure-resistant container, and move the liquid crystal envelope with the air inside the pressure-resistant container evacuated so that its plate surface is approximately perpendicular to the liquid crystal surface and inject the liquid crystal envelope. A liquid crystal display device characterized in that the hole is immersed in the liquid crystal in the liquid crystal reservoir container, and then the reduced pressure in the pressure container is restored to its original state, and the liquid crystal is injected into the slit of the liquid crystal envelope. liquid crystal injection method.