JPS6049889B2 - 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 that display characters, numbers, and other arbitrary patterns using the electro-optical effect of two conductive plates arranged in parallel and a thin layer of liquid crystal sandwiched between them. It is being

Some of the following methods are conventionally known for injecting liquid crystal 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-type cell structure.

(2) In an envelope that has a sandwich cell structure in advance,
A method in which two or more through holes are provided in the gap between the plates, and injection is made through at least one of the holes by utilizing capillary action.

(3) A method in which the liquid crystal is injected while heating the airtight container 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-type cell structure so that no air bubbles remain. It is inappropriate to do so. The remaining bubbles not only impair the appearance of the display device but also significantly shorten its driving life. Method (2), which utilizes capillarity, is extremely difficult to inject into long and narrow sandwich-type cells, and especially in display devices where the electrode material is provided on the glass plate surface, the glass surface and the electrode Since the affinity between substances and liquid crystals is different, liquid crystals do 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 disadvantage that the liquid crystal itself comes into contact with the outside air and that air dissolved in the liquid crystal cannot be removed at the same time. (4
) method 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 the process is complicated and there are problems with workability, and it is not suitable for mass production. Not suitable. The present invention aims to provide a liquid crystal injection method that is easy to work with, mass-producible, and has good 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 means for controlling the movement of objects inside from the outside.
For example, in a state where an airtight liquid crystal envelope having at least one injection hole is installed on a rotating shaft that can be controlled from the outside on the upper part, the air inside the pressure-resistant container is exhausted, and the inside of the liquid crystal envelope is After removing the air and dissolved air in the liquid crystal, the injection hole portion of the envelope is immersed in the liquid crystal, the reduced pressure state of the pressure-resistant container is returned to atmospheric pressure, and the envelope is heated. This method is characterized by injecting liquid crystal into an envelope under pressure.

In the present invention, instead of transferring the liquid crystal in a transfer tube, the envelope is moved and immersed in the liquid crystal using a means provided in a pressure-resistant container that can be controlled from the outside. By applying pressure to the surface and heating the envelope, the liquid crystal is transferred into the envelope! The point is that

In the present invention, since dissolved air in the liquid crystal can be removed during the exhaust process, deterioration of the liquid crystal can be prevented over a long period of time.

Moreover, there is no need for any extra conduit for external injection.
In particular, for devices with a narrow display area, such as the display device of a wristwatch, an injection hole is provided in the insulating part to avoid damaging the appearance of the display surface by providing an injection hole in the display surface of the envelope. There is no need to provide any extra conduit for injection externally, and the workability is extremely good. In addition, since the liquid crystal envelope with a sandwich cell structure can be installed vertically and liquid crystal can be injected from the side of the panel, it is possible to simultaneously manufacture a large number of liquid crystal display devices with good uniformity in a small area. There are advantages. Furthermore, a major feature of the present invention is that the liquid crystal is injected into the heated liquid crystal envelope, and since the liquid crystal envelope is heated, when air in the pressure container is evacuated, etc. Moisture and gas adhering to the inside and outside can be quickly evaporated.

Furthermore, the viscosity of the liquid crystal becomes low in the heated liquid crystal envelope, and the injection is short and uniform, making the process extremely suitable for mass production. ) An embodiment of the present invention will be described in detail below.

Figure 1 shows the basic structure of an apparatus for carrying out the method of the present invention, in which 1 is 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 5 by, for example, a handle 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 container 4 containing a liquid crystal 3 is placed at the bottom of the pressure container 5. This pressure-resistant container 5 is connected to an exhaust system via a valve 8, and is configured to allow air to be taken in via a valve 9. In the above configuration, first, the valve 8 is opened to operate the exhaust system, and the pressure vessel 5 and the heated envelope 1 are exhausted.

Note that the envelope 1 is heated, for example, by the method shown in FIG. 3, as will be explained later. As a result, moisture and gas in the envelope 1 are quickly exhausted to create a vacuum state, and air dissolved in the liquid crystal reservoir 3 can also be eliminated. After sufficient exhaustion, the valve 8 is closed, the handle 6 is rotated, and the suspended envelope 1 is moved to the lower part so that the injection hole 2 is immersed in the liquid crystal 3. After the liquid crystal has sufficiently covered the injection hole 3, the valve 9 is opened. Air flows into the pressure container 5 which is in a vacuum state, and pressurizes the liquid surface of the liquid crystal 3. As a result, the liquid crystal flows into the envelope 1 and spreads uniformly two-dimensionally between the glass plates. After the liquid crystal injection is completed in this way, the pressure container 5 is taken out 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.

There is no marking on the display surface for the injection hole to be drilled by a drilling machine.
When sealing the periphery of the gap in the envelope with a sealant 10 such as frit glass or epoxy adhesive, a central portion 11 at one end of the envelope is used so that the gap between the plates and the outside communicate with each other. Alternatively, it may be formed by providing a gap in the tip portion 12. With this structure, there is no need to provide an injection member outside the envelope. FIG. 3 is a conceptual diagram showing that liquid crystal is injected into the heated envelope 1 by surrounding the envelope of FIG. 1 with a heating body 14. By this heating mechanism, the liquid crystal is The liquid crystal is heated during pouring into the envelope, and its viscosity decreases during pouring, so that the liquid crystal is quickly poured and spread evenly between the plates.

The heating element 14 in FIG. 3 may be provided either inside or outside the pressure vessel 5, or the outer vessel may be heated by a device completely separate from the pressure vessel. 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 2
0 controls its movement. 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 lifespan of the display device.Also, it is possible to prevent the insulating parts from deteriorating without damaging the appearance of the display surface. Since the injection hole can be provided in the gap, 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 envelope can be installed vertically,
It is highly suitable for mass production since it can simultaneously manufacture a large number of liquid crystal display devices in a small area. Furthermore, since the liquid crystal is injected into a heated liquid crystal envelope, the viscosity of the liquid crystal is low, and the injection is carried out quickly and uniformly, making this method extremely suitable for mass production.

[Brief explanation of drawings]

Fig. 1 is a basic schematic configuration diagram of an apparatus for carrying out the method of the present invention, Figs. 2A and b are front views of the envelope, respectively, and Figs. 3 and 4 are for carrying out the method of the present invention, respectively. This is a schematic diagram of the device. 1, 18...Liquid crystal envelope, 2, 11, 12...
- Injection hole, 3...Liquid crystal, 4...Liquid crystal reservoir, 5...Pressure container, 14...Heating body.

Claims (1)

[Claims] 1. A liquid crystal envelope having a slit into which liquid crystal is injected and at least one injection hole provided on the outer periphery and a liquid crystal reservoir containing liquid crystal are placed in an airtight pressure-resistant container, and the above-mentioned pressure-resistant container is placed. The liquid crystal envelope is heated by immersing the injection hole of the liquid crystal envelope into the liquid crystal in the liquid crystal reservoir container with the air inside exhausted, and returning the reduced pressure state in the pressure resistant container to its original state. A method for injecting liquid crystal into a liquid crystal display device, the method comprising injecting liquid crystal into the slits of a liquid crystal display device.