JPS6048738B2 - Method for manufacturing two-layer guest-host type liquid crystal display element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a two-layer guest-host type liquid crystal display element in which liquid crystal is sealed between three glass substrates, and a method for manufacturing the same.

As a guest-host type positive color liquid crystal display, a dichroic dye is mixed with a liquid crystal having a 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 lowers the light transmittance, resulting in poor visibility.

Also, as a way to increase contrast without using a polarizing plate,
A two-layer structure with liquid crystal layers on both sides of a transparent glass substrate is adopted, and the same pattern is displayed on the two liquid crystal layers. At that time, the direction of the light absorption axis of the dye in one liquid crystal layer is set on the other side. A method has been proposed in which liquid crystals are aligned perpendicular to the absorption axis direction in the 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 solves the above-mentioned drawbacks, can be manufactured using a simple manufacturing process and method, and also facilitates the formation of transparent electrodes and the routing of conductive wires to external connection terminals, and has a high manufacturing yield at low cost and high contrast. This was done for the purpose of providing a good two-layer guest-host type liquid crystal display element.

A feature of the present invention is that transparent electrodes having a larger area than the horizontal alignment layer portion to be formed are formed on both the front and back surfaces of a transparent substrate such as glass.

Next, photosensitive polyvinyl alcohol is coated 5 on the transparent electrode, and a mask having an opening pattern corresponding to the display area is placed on one side of the photosensitive polyvinyl alcohol coating, and from the side where the mask is placed, It is exposed to light to harden the portions of the polyvinyl alcohol coating on both the front and back surfaces corresponding to the openings of the mask. Next, the uncured portion of the polyvinyl alcohol film was removed by washing with water, and then heat-treated to form a horizontal alignment layer portion made of a cured polyvinyl alcohol thin film having a display pattern of the same shape on both sides of the transparent substrate. .

The present invention will be explained below based on the drawings. FIGS. 1A to 1B show the process of forming a horizontal alignment layer on the intermediate glass substrate of the liquid crystal display element of the present invention.

First, as shown in FIG. 1A, InO is deposited on both sides of a glass substrate 1 by screen printing, vapor deposition, or the like. The transparent electrodes 2a and 2b are formed into a predetermined shape. Here, in a liquid crystal display element in which the horizontal alignment layer is patterned to correspond to the display area and the alignment with the liquid crystal corresponding to the background area is changed as in the present invention, the displayed pattern is different from the transparent electrode 2.
a) Since it is determined by the alignment layer pattern, not by the pattern in 2b, the transparent electrode pattern only needs to be larger than the outer shape of the pattern to be displayed, and the conductor wiring with the external connection terminal should not overlap with the counter electrode. Is it possible to ignore it and move around? Next, as shown in FIG.
a) Form 3b. Furthermore, as shown in Figure C, it had a pattern 4 with a shape corresponding to the display section. mask 5,
After alignment, the glass substrate 1 is applied, and ultraviolet light is irradiated from above the mask 5 (in the direction of the arrow in the figure).
Glass substrate 1, transparent electrodes 2a, 2b) Photosensitive polyvinyl alcohol coatings 3a, 3b all transmit ultraviolet light; The photosensitive polyvinyl alcohol coatings 3a and 3b on both sides of the lath substrate 1 are cured only in the portions corresponding to the patterns 4 of the mask 5. Next, after removing the uncured photosensitive polyvinyl alcohol by washing with water, the entire glass substrate is heat-treated at 120°C to 150°C to completely cure the polyvinyl alcohol and remove the transparent electrode 2.
Horizontal alignment layers 3A and 3B made of polyvinyl alcohol thin films having a shape corresponding to the display area are formed to increase the adhesion to a and 2b, as shown in FIG. 1 and 2. The horizontal alignment layers 3A and 3B thus formed have no misalignment on both sides of the glass substrate 1, and have exactly the same pattern outline. Next, a method for manufacturing the liquid crystal display element of the present invention will be explained.

FIG. 2 is a diagram showing the structure of the liquid crystal display element of the present invention.
In manufacturing a liquid crystal display element, first, a glass substrate 1 having horizontal alignment layers 3A and 3B formed as described above on both the front and back surfaces is heated by N.C. N-dimethyl-N-octadecyl-3-aminopropyltrimethoxysil chloride (
The glass substrate 1 is immersed in a solution of an alignment agent, such as DMOAP) or chromium myristate complex, which gives vertical alignment to the liquid crystal, and vertical alignment treatment is performed on both surfaces of the glass substrate 1 other than the horizontal alignment layers 3A and 3B. At this time, the solution of the alignment agent that provides the vertical alignment has extremely weak adsorption force to the horizontal alignment layers 3A, 3B, and does not adhere to the horizontal alignment layers 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 horizontal alignment layers 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. This improves the contrast. On the other hand, the surfaces of the two glass substrates 6 and 7 to be disposed opposite to the glass substrate 1 are subjected to the same treatment as the vertical alignment treatment described above. Then, the glass substrate 1 and two glass substrates 6 and 7 facing the glass substrate 1 are adhered to each other with an adhesive 8 such as epoxy resin while maintaining a distance of 5 to 20 μm, and a liquid crystal display is formed. Create a cell. A liquid crystal 9 with positive dielectric anisotropy mixed with a dichroic dye is added to the liquid crystal cell.
to complete the liquid crystal display element. In addition, 2c, 2
d is a counter electrode to 2a and 2b, respectively. Two-layered guest manufactured in this way. The host type liquid crystal display element had good contrast.

As explained above, in the present invention, the liquid crystal alignment layer portion corresponding to the display area is a horizontal alignment layer made of a thin film of polyvinyl alcohol obtained by exposing photosensitive polyvinyl alcohol, and the liquid crystal alignment layer portion corresponding to the background area is a horizontal alignment layer made of a thin film of polyvinyl alcohol obtained by exposing photosensitive polyvinyl alcohol. The liquid crystal alignment layer part,
By forming a vertically aligned layer, the manufacturing process is simple, transparent electrode formation and conductive wire wiring are easy, and the manufacturing yield is good.Therefore, it is inexpensive and a two-layer guest with good contrast.
It has the great advantage of providing a host-type liquid crystal display element.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings are all examples of the present invention, and FIGS. FIG. 2 is a sectional side view of a liquid crystal display element of the present invention obtained by a method according to the present invention.

1...Glass substrate, 2a, 2b...
Transparent electrode, 2c, 2d... Counter electrode, 3a, 3
b...Photosensitive polyvinyl alcohol coating film, 3A, 3B
...Horizontal alignment layer, 4...Pattern, 5
...Mask, 6,7...Glass substrate,
8...Adhesive, 9...Liquid crystal.

Claims (1)

[Claims] 1 Transparent electrodes having an area larger than the horizontal alignment layer portion to be formed are formed on both the front and back surfaces of the transparent substrate, and after coating photosensitive polyvinyl alcohol on the transparent electrodes, an opening with a shape corresponding to the display area is formed. A mask containing the polyvinyl alcohol is placed on one side of the photosensitive polyvinyl alcohol coating, and the other side of the photosensitive polyvinyl alcohol coating is exposed to light to harden the portions of the polyvinyl alcohol coating on both the front and back surfaces that correspond to the openings in the mask. The second method is characterized in that the uncured portion of the alcohol coating film is removed by washing with water, and then heat treated to form horizontal alignment layer portions made of a cured polyvinyl alcohol thin film having display pattern of the same shape on both sides of the transparent substrate. A method for manufacturing a layered guest-host type liquid crystal display element.