JPS5848085B2 - Liquid crystal injection method for liquid crystal display device - Google Patents

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.

Liquid crystal display devices are already known as devices in which two conductive plates are arranged parallel to each other, a thin layer of liquid crystal is sandwiched between them, and the electro-optic effect is used to display characters, numbers, and other arbitrary patterns. ing.

Conventionally, several methods shown below are known for liquid crystal injection into such a liquid crystal display device.

(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-shaped cell structure.

(2) Into the envelope, which 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 the liquid crystal is sealed in an airtight container in which the liquid crystal is injected while heating and evacuating the inside.

(4) After connecting 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, A method in which a gas is injected under pressure into the liquid crystal 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 although it is possible to perform it in a laboratory, it is difficult to implement it industrially. It is inappropriate to do so.

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 difficult to inject into liquid crystal. Due to the different affinity between the liquid crystal and the liquid crystal, the liquid crystal does not fit uniformly and air bubbles tend to remain.

Although method 3 is suitable for uniformly placing the liquid crystal in the envelope, it has the drawback 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 No. 4 is suitable for uniformly placing the liquid crystal in the envelope, and also takes into account the elimination of dissolved air in the liquid crystal, but there is a problem in workability.

The present invention proposes a new method that is an improvement on method 4.

The present invention differs from method 4 above in that the liquid crystal is transferred, and while method 4 uses pressure applied to the liquid crystal surface in the transfer tube, the present invention In the invention, the movement of the liquid crystal reservoir inside the pressure container is controlled from the outside,
The point is that the work of transferring it to the envelope is added.

By doing this, the liquid crystal comes into less contact with the container, and there is less contamination due to contact with the container.

This method can perform the same function as method 4.

That is, the liquid crystal can be uniformly injected into the surrounding air, and dissolved air in the liquid crystal can be removed, thereby preventing deterioration of the liquid crystal.

Furthermore, the work is simpler than method 4.

An embodiment of the present invention will be described below.

The figure shows a schematic configuration of an apparatus for carrying out the method of the present invention, in which 1 is an envelope to which electrodes have been attached, a glass plate 2 is
The sheets are held parallel by spacers.

An injection hole 3 is formed in this envelope 1, and this injection hole 3
A liquid conduit 2 is provided in communication with the section.

The envelope 1 is placed on the heating plate 4, and the liquid conduit 2 is placed so as to protrude from the edge of the heating plate 4 so that its tip is directed downward.

A liquid crystal reservoir 6 containing liquid crystal 5 is arranged further below the tip of the liquid conduit.

The liquid crystal reservoir 6 is suspended by a suspension string 8 from a rotating shaft 7 that can be controlled from the outside, and can be moved up and down by operating a handle 9.

A pressure container 10 containing these is connected to an exhaust system through a valve 11 and is configured to be able to take in air through a valve 12.

In the above configuration, first, the valve 11 is opened to operate the exhaust system, and the pressure vessel 10 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 5 in the liquid crystal reservoir is also removed.

After sufficient exhaustion, valve 11 is closed.

Next, the handle 9 is rotated to move the liquid crystal reservoir 6 upward, and the liquid conduit 2 of the envelope is immersed in the liquid crystal 5.

After the liquid conduit 2 is fully immersed in the liquid crystal 5, the valve 12
open.

Air flows into the pressure container 10 in a vacuum state and pressurizes the liquid surface of the liquid crystal 5.

As a result, the liquid crystal 5 flows into the envelope 11 and spreads uniformly into the gap between the glass plates.

After finishing the liquid crystal injection in this way, the envelope 1 is taken out from the pressure container 10 and the next envelope is installed.

Repeat this operation below. Furthermore, if a large number of liquid crystal display devices are to be manufactured at the same time, a large number of liquid crystal reservoirs may be arranged side by side, or elongated liquid crystal reservoirs may be arranged.

As mentioned above, since dissolved air in the liquid crystal is eliminated during the exhaust process of the envelope for sealing the liquid crystal, there is no air bubbles in the liquid crystal display device, and no harmful air is dissolved. can be prevented.

Similarly, by heating the envelope, moisture and gas adhering to the surface of the container can be quickly evaporated.

Furthermore, since the viscosity of the liquid crystal is low, it can be easily and uniformly injected.

As a result, liquid crystal display devices can prevent the deterioration of the characteristics of liquid crystal, which has been a problem in practical use, and can extend the life of the display device.In addition, it is easy to work, has high injection reliability, and can be mass-produced. It is also rich in sexuality.

[Brief explanation of drawings]

The figure is a schematic configuration diagram of an apparatus for carrying out the method of the present invention.

Claims (1)

[Claims] 1. Connect a liquid conduit to an injection hole of an airtight liquid crystal envelope having a slit into which liquid crystal is injected, and place the liquid crystal envelope on a heating body so that the liquid conduit protrudes from the edge of the heating body. Place the liquid crystal envelope in an airtight pressure-resistant container so that the liquid crystal tube faces downward, and move the liquid crystal reservoir containing the liquid crystal vertically into the pressure-resistant container. While the liquid crystal envelope is heated, the air in the pressure container is evacuated, and in this evacuated state, the liquid crystal reservoir is moved, and the liquid crystal in the liquid crystal reservoir is injected into the liquid crystal container. A liquid crystal injection method for a liquid crystal display device, characterized in that the liquid crystal is injected into the slit of the liquid crystal envelope by immersing the liquid crystal in the liquid crystal container, and then returning the reduced pressure state in the pressure container to the original state.