JPS5952407B2 - Method for forming alignment film for liquid crystal display element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming an alignment film on a transparent glass substrate of a liquid crystal display element, in particular a method for forming an alignment film on both the front and back sides of a transparent glass substrate in the middle of a color liquid crystal display element consisting of two liquid crystal layers. The present invention relates to a method of forming a film.

For guest-host type positive color liquid crystal display, dichroic dye is mixed with Nn type liquid crystal with negative dielectric anisotropy, and the liquid crystal is oriented in one direction at a slight angle from perpendicular to the substrate. It is common practice to use a polarizing plate to further increase the contrast, but the polarizing plate reduces light transmittance, resulting in poor visibility. In addition, as a method to increase contrast without using a polarizing plate, we have adopted a two-layer structure in which liquid crystal layers are provided on both sides of a transparent glass substrate, and the same pattern is displayed on the two liquid crystal layers. A method has been proposed in which liquid crystals are arranged so that the direction of the light absorption axis of the dye therein is perpendicular to the direction of the absorption axis in the other liquid crystal layer.
However, the alignment film of the conventional positive color liquid crystal display element was formed on the substrate by oblique evaporation, which required a large evaporation apparatus and had the drawback of poor mass productivity.
Furthermore, when the liquid crystal has a two-layer structure, it is difficult to align the electrode patterns on each insulating substrate, the manufacturing process must be complicated, and the resulting liquid crystal display element is also expensive. The present invention has been made for the purpose of solving the above-mentioned drawbacks, and providing a positive color liquid crystal display element which can be manufactured by a simple manufacturing method and a simple process, and which has a high manufacturing yield and is less expensive.

A feature of the present invention is that an alignment film of the same shape is simultaneously formed on both the front and back surfaces of the intermediate transparent glass substrate of a liquid crystal display element in which the liquid crystal has a two-tank structure with a transparent glass substrate sandwiched between them. It's because I let it happen.

The present invention will be explained below based on the drawings.

FIGS. 1A to 1B show the process of forming an alignment film on an intermediate transparent glass substrate of a liquid crystal display element according to the present invention.

First, as shown in FIG. 1A, In is applied to both sides of the glass substrate 1 by screen printing, vapor deposition, or the like. O. The transparent electrodes 2a, 2b are formed into a predetermined shape. In the liquid crystal display element in which the alignment film is patterned to correspond to the display area as in the present invention, and the alignment with the liquid crystal corresponding to the background area is changed, the displayed pattern is formed by the transparent electrodes 2a, 2b.
The transparent electrode pattern only needs to be larger than the outline of the pattern to be displayed, and the conductor wiring with the external connection terminal can be routed without regard to overlap with the counter electrode. It is possible to route it around.

Next, as shown in FIG.
Alignment films 3a, 3 which are resin coatings such as polyimide or polyvinyl alcohol that align liquid crystal molecules horizontally with respect to the substrate.
Form b. Furthermore, as shown in FIG.
A mask 6 having a pattern mask 5 having a shape corresponding to the display area is aligned and applied to the glass substrate 1, and light is irradiated from above the mask 6 (in the direction of the arrow in the figure). Since the glass substrate, transparent electrode, alignment film, and photosensitive resin coating are all transparent, the photosensitive resin coatings 4a and 4b on both sides of the glass substrate are cured at the same time, and when the phenomenon is fixed, only the cured resin coatings have the same shape on both sides. remains on the alignment films 3a and 3b. Next, the glass substrate 1 is immersed in an etching solution, and as shown in FIG.
Form A and 3B. The alignment films 3A and 3B thus formed have exactly the same pattern outline without any positional deviation on both sides of the glass substrate 1. A glass substrate 1 having the alignment films 3A and 3B created in this way on its surface.
Next, a method for manufacturing a liquid crystal display element using the method will be described.

FIG. 2 is a diagram showing the structure of a liquid crystal display element according to the present invention. In manufacturing a liquid crystal display element, first, alignment films 3A and 3B for horizontally aligning the liquid crystal formed as described above are applied to the surface. glass substrate 1 having N-N-dimethyl-N-
Both surfaces of the glass substrate 1 other than the alignment films 3A and 3B are immersed in a solution of an alignment agent that gives vertical alignment to liquid crystals, such as octadecyl-3-aminopropyltrimethoxysilyl chloride (DMOAP) or chromium myristate complex. Perform vertical alignment treatment on top.

At this time, the solution of the alignment agent that provides the vertical alignment has extremely weak adsorption force to the alignment films 3A, 3B, and does not adhere to the alignment films 3A, 3B. Next, the surface of the glass substrate 1 is wrapped with absorbent cotton or the like to align the liquid crystal molecules on the alignment films 3A and 3B in a certain direction. At this time, the wrapping direction must be selected so that the directions are perpendicular to each other on both sides of the glass substrate 1. On the other hand, this glass substrate 1
The surfaces of the two insulating substrates 7 and 8 to be disposed opposite to each other are subjected to a treatment similar to the vertical alignment treatment described above. Then, the glass substrate 1 and the two insulating substrates 7 and 8 facing the glass substrate 1 are adhered with an adhesive 9 such as an epoxy resin, keeping the distance between each substrate at 5 to 20 μm, and the liquid crystal display is Create a cell.

A liquid crystal 10 having a positive dielectric anisotropy mixed with a dichroic dye is filled in the liquid crystal cell to complete a liquid crystal display element. In addition,
2C and 2d are counter electrodes to 2a and 2b, respectively. In the example shown in FIGS. 1 and 2, the photosensitive resins 4a and 4b are exposed by irradiating light from directly above the glass substrate 1, that is, in a direction perpendicular to the master 6. However, in the example shown in FIG. An example was shown.

In other words, when the placement location of the completed liquid crystal display element is determined and the viewing direction is determined, the light is intentionally directed in the same direction as the viewing direction (as shown in Figure 3A). When the photosensitive resins 4a, 4b are cured by irradiating the glass substrate 1 from the arrow direction), the resulting alignment films 3A, 3
B is as shown in the opening of FIG. 3, and the same shape is formed on both sides of the glass substrate 1 with shifted positions. in this way,
By forming the alignment films 3A and 3B, it is possible to eliminate difficulty in viewing due to pattern shift of the display section depending on the viewing direction.
The liquid crystal display element produced in this way is shown below.
Figure 3 is c.

In addition, in FIG. 3, 2a and 2b are transparent electrodes, 2C,
2d is a counter electrode, 3a and 3b are alignment films, 5 is a pattern mask, 7 and 8 are counter insulating substrates, 9 is an epoxy resin adhesive, and 10 is a liquid crystal. As you can see from the above explanation,
The effects of the present invention are that a liquid crystal display element can be manufactured very easily and through a simple process, and that a liquid crystal display element that can also be adapted to viewing directions can be provided.

Hereinafter, the present invention will be explained in more detail based on Examples.

Example 1. After forming transparent electrodes such as In2O3 on a 1 mm thick glass substrate by screen printing, vapor deposition, etc.,
H6O2O silane coupling agent (manufactured by Toray Silicon Co., Ltd.)
Surface treatment.

Next, a solution prepared by diluting high-purity Trenise (polyimide) (manufactured by Toray Industries, Inc.) six times with dimethylacetamide was applied to both sides of the glass substrate using a spinner at a rotation speed of 4000 rpm, dried at 200°C, and the glass substrate was Horizontal alignment films are formed on both surfaces.

Next, apply FSR photoresist (manufactured by Fuji Pharmaceutical Co., Ltd.).
The photoresist on both sides of the glass substrate was coated on the entire surface of both sides of the glass substrate using the spinner described above, a mask was applied, and the photoresist was exposed to parallel light to partially cure the photoresist on both sides of the glass substrate to form an etch mask pattern. After that, the horizontal alignment film made of high-purity trenise was etched with a 5% aqueous solution of sodium hydroxide, and then heat treated at 350°C for 30 minutes to completely harden the trenise, forming a horizontal alignment film with a shape corresponding to the display area. Formed. Next, the glass substrate is immersed in a DMOAP aqueous solution for 5 minutes, then washed with pure water, and a vertical alignment process is performed on the glass substrate other than on the horizontal alignment film, so that the liquid crystals are aligned at right angles on the front and back sides. I wrapped it with absorbent cotton. In addition, the two insulating substrates that should face the glass substrate were also subjected to the vertical alignment two-way treatment in the same way, and the three substrates were aligned as specified.
A liquid crystal cell was manufactured by adhering each substrate while maintaining a distance of 12 μm. A dye mixed liquid crystal RO-GH- is added to the liquid crystal cell.
605-15B (manufactured by Hoffmann-La Rochie) was sealed to complete a liquid crystal display element.

The completed liquid crystal display device displayed a blue color with high contrast. When the response speed was measured at room temperature, it was found to be excellent as shown below. Speed of applying voltage and erasing display: 40msec Speed of erasing voltage and displaying display: 200msec

[Brief explanation of drawings]

The drawings are all examples of the present invention, and FIGS. 1A to 2 are diagrams showing the alignment film forming process of the liquid crystal display element of the present invention, and FIG. FIG. 3 is a sectional side view of the obtained liquid crystal display element, and FIGS. 3A to 3C are embodiments of the present invention different from those in FIGS. 1 and 2. 1: Glass substrate, 2a, 2b: Transparent electrode, 2C, 2d:
Counter electrode, 3a, 3b: alignment film, 3A, 3B: alignment film having a shape corresponding to the display section, 4a, 4b: photosensitive resin film, 5
: pattern mask, 6: mask, 7, 8: insulating substrate, 9
: Adhesive, 10: Liquid crystal.

Claims (1)

[Claims] 1. An alignment film is formed on both the front and back sides of a transparent glass substrate, and a photosensitive resin coating is formed on the alignment film, and the photosensitive resin coating on both sides of the transparent glass substrate is cured by one exposure. A method for forming an alignment film for a liquid crystal display element, which comprises simultaneously forming alignment films in the same shape on both sides of a transparent glass substrate. 2. When exposing the photosensitive resin coating, maintain the angle between the transparent glass substrate and the light source for exposure at the same angle as the angle at which the assembled liquid crystal display element is observed, and expose the photosensitive resin coating on both sides of the transparent glass substrate. 2. A method for forming an alignment film for a liquid crystal display element according to claim 1, wherein the alignment film is cured by exposure to light.