JPS63106727A - Manufacture of liquid crystal display panel - Google Patents

Abstract

PURPOSE:To uniformly and easily form an oriented film on a substrate by coating an orientating agent on the substrate by a spray which sprays a fluid. CONSTITUTION:The orienting agent is sprayed on a substrate 12 with a spray gun 11 having a fine two-fluid spray nozzle to form an oriented film 13. Though the oriented film 13 obtained in this manner is uniformly coated on the substrate 13, the shape of minute liquid drops reflects ruggedness of the surface of the oriented film 13 in this sprayed state and a uniform film thickness is not always obtained. Therefore, gaseous nitrogen is sprayed from a gas spray nozzle 14 outward from the center of the substrate to uniformly spread the oriented film 13 before the orienting agent is dried. The substrate 13 coated with the oriented film 13 is gradually cooled after heating by drier to form the oriented film 13 having a uniform film thickness. Thereafter, the rubbing treatment is performed, and two substrates are stuck with a certain gap between them, and liquid crystal is charged between them to produce a liquid crystal display panel.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a liquid crystal display panel that displays images and alphanumeric links, and particularly relates to a method for manufacturing a liquid crystal display panel with a large area and large display capacity. .

Conventional technology Currently, liquid crystal display panels are used for everything from relatively small devices with small display capacity such as watches and calculators, to devices with large display capacity such as OA equipment terminals such as VOC pull-up computers and word processors, and color televisions, and even screens. It is developing into a larger size.

Conventionally, methods using spin codes, printing methods, and the like have been known as means for forming alignment films in these liquid crystal display panels. These two methods will be explained below.

In the spin code method, a substrate is placed on a disc-shaped rotating body,
In this method, the substrate is suctioned and fixed onto a rotating body using a vacuum pump, an alignment agent is dropped onto the top surface of the substrate, and then the substrate is rotated at several thousand rpm for several minutes to form an alignment film. In this method, the alignment film is relatively thin (about several hundred angstroms),
Since it has excellent surface smoothness, it has the advantage that the electrical properties of a liquid crystal display panel are less degraded by the alignment film.

Next, the printing method is a method in which an alignment agent is transferred onto a glass substrate using a resin relief plate or the like having a predetermined shape to form an alignment film. This method produces a thicker alignment film (about 1,000 angstroms) than the spin coating method.

Although its surface smoothness is somewhat inferior, it is suitable for mass production and has low manufacturing costs, so it is actually widely used in the production of liquid crystal display panels.For example, National Technical Report, Vol. 28, No. 1 ( 1982) (Nat
ional Technical Report, V
ol.

28, No. 1 (1982)) Problems to be Solved by the Invention In manufacturing methods using the spin code method or printing method, the following problems occur when forming an alignment film on a substrate for a large liquid crystal display panel. .

In the spin code method, the screen size is limited to about 12 inches at most, and if the screen size is larger than this, the alignment film will be thick at the center of the substrate and thin at the edges, and will not be formed uniformly.

In addition, in order to prevent large-area substrates from being damaged by the rotating body even during high-speed rotation, the spin cord device should be made larger.
In addition, a vacuum pump with strong suction power is required, which increases the cost. Furthermore, in a mass production process, since it takes several minutes to form an alignment film on one substrate, the number of spin code devices must be increased, which is disadvantageous in terms of cost.

On the other hand, with the printing method, it is possible to form an alignment film on a substrate with a larger screen size than with the spin code method, but
In this case, a huge device is required, manufacturing costs are high, and process control is complicated.

As described above, with conventional technology, when forming an alignment film on a substrate with a large screen size, expensive, complicated and large equipment is required, and the uniformity of the alignment film also lacks reliability. There is.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention applies a step of applying an alignment agent to the substrate by spraying a fluid in the form of mist, thereby uniformly applying an alignment film to the substrate. It is quick and easy to form.

Function The present invention solves the above problems as follows. First, in the method for forming an alignment film according to the present invention, only a spray that sprays out the alignment agent in the form of mist is used.
It is very simple and the production cost is very low. moreover,
Even if a gas jetting step is provided, it is still possible to form a uniform alignment film easily and inexpensively just by using a gas jetting spray.

Embodiment An embodiment of the method for manufacturing a liquid crystal display panel according to the present invention will be described using the process diagram shown in FIG.

First, using a spray gun 1) manufactured by Spraying Systems Japan, which has a two-fluid fine atomizing nozzle that can form a fine atomized fluid by mixing gas and liquid, polyimide was sprayed. 1.67% with calpitol (diethylene glycol monobutyl ether)
An alignment agent diluted to
Figure 1(a)). At this time, the atomizing air pressure was set to 1.0 kg/cj, and the distance between the substrate 12 and the injection port was set to 5.
It was set to about 0 cm. The spray nozzle used had a circular spray width of 42 cm in diameter at a point 381 mm away from the injection port when the injection air pressure was 2.01 qr/cd, and the liquid flow rate was 2.64 cm. /hr. If the concentration of the alignment agent is 5% or more, the viscosity is too high, the alignment agent thickly covers the substrate 12, and the unevenness becomes significant, so the concentration should be 1% or more.
The concentration of the alignment agent is preferably between 5% and 1.67%, which is preferable because the substrate 12 can be covered with a suitable thickness. If the distance between the substrate 12 and the injection port is too short, a large amount of alignment agent will be sprayed per unit area, resulting in a thick alignment film 13; if the distance is too far, the sprayed droplets will be rough on the substrate 12. Alignment film 1 is adhered at intervals and uniformly □
3 was not formed, so a thickness of about 50 cm was desirable.

The injection air pressure is 0. If the amount is less than 5 kg/cd, the alignment agent will be dropped without becoming atomized, and an alignment layer will be formed unevenly on the substrate 12. In addition, 2.0 kg/a (at more than 1.0 kg/e+J, the liquid flow rate becomes large and a large amount of alignment agent is applied per unit area, resulting in a thick layer), so 1.0 kg/e+J is desirable.

Although the alignment film 13 obtained through the above steps uniformly covers the substrate, the shape of the small droplets is reflected in the unevenness of the surface of the alignment film 13 while it is being sprayed. There is. Therefore, a uniform film thickness is not necessarily obtained.In order to improve this situation, after the above process and before the alignment agent dries, a gas is ejected from the center of the substrate outward. Nitrogen gas was sprayed from the nozzle 14 to uniformly stretch and spread the alignment film 13. Nitrogen gas pressure is 1.0
Below kir/-, the alignment film 13 does not stretch and the weight is 5.0 kg/-.
- Since there is a risk that the alignment film on the substrate will be blown away, when the weight was set to about 3.0 kg/-, the alignment film 13 was evenly distributed.
The alignment film 13 was stretched and spread, and the alignment film 13 was uniform and had a uniform thickness. (In Figure 1)) When the substrate covered with this alignment film 13 was heated in a dryer at 300°C for 1 hour and then slowly cooled, an alignment film 13 having a uniform thickness was formed. was completed.

After forming the alignment film 13 as described above, a rubbing process was performed, the two substrates were bonded facing each other with a certain gap, and liquid crystal was injected. It was possible to manufacture a liquid crystal display panel at low cost.

Effects of the Invention As can be seen from the results shown above, the method for manufacturing a liquid crystal display panel of the present invention is capable of applying an alignment film to a substrate for a liquid crystal display panel having a large screen area using a very simple device. By having a process that can be easily and inexpensively formed, a liquid crystal display panel can be manufactured very easily and inexpensively.

[Brief explanation of the drawing]

FIG. 1 (al and bl are perspective views showing the manufacturing process for forming an alignment film in one embodiment of the present invention. 1) Spray gun with a two-fluid spray nozzle,
12...Substrate, 13...Alignment film, 14
・・・・・・Gas jet nozzle.

Claims (2)

[Claims] (1) A method for manufacturing a liquid crystal display panel, comprising the step of applying an alignment agent to a substrate by jetting a fluid in the form of a mist. (2) The method for manufacturing a liquid crystal display panel according to claim (1), further comprising the step of spraying a gas onto the substrate after the step of applying an alignment agent to the substrate.