JPH02311802A - Formation of color filter of color liquid crystal display element - Google Patents

Abstract

PURPOSE:To surely obtain the large-area color liquid crystal display element at a high yield by forming color filters on a substrate by using a printing method, then by uniformly pressing the color filters by means of a high-accuracy press or roller after half curing. CONSTITUTION:The color filters 10R, 10G, 10B printed by offset printing, etc., are put into the half cured state and thereafter, the surface of the color filters 10 is pressed by the press or roller having the high plane accuracy to relieve the surface ruggedness of the color filters 10 themselves. Since the surface ruggedness of the color filters 10 is thereby decreased to more than half 3mum surface ruggedness of the conventional element or below, the final surface ruggedness is <=0.05mum in range even if the selection width of a smoothing material is expanded or the forming thickness of the smooth layer material is reduced. The STN type large-area color liquid crystal display element is stably and uniformly obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of forming a color filter for a color liquid crystal display element.

BACKGROUND OF THE INVENTION In recent years, the fields of use of liquid crystal display elements have expanded from calculators and watches to office automation equipment image processing devices, liquid crystal televisions, and all other fields. It is well known that this type of display utilizes the optical anisotropy of liquid crystal.

FIG. 3 shows a cross section of the basic structure of an example of such a color liquid crystal display element. In FIG. 3, 1 is a segment substrate made of glass, 3 is a transparent electrode (ITO) forming a segment provided on the segment substrate 1, and s is an alignment film formed on the transparent electrode 3. Further, a black matrix 9 is formed on the common substrate 2 made of a glass material, and between the black matrix 9 there are R, G,
, H color 7 Ikl' 1 oR, 1oG , 1
0B is formed, and there is a smoothing layer 13 for filling in the unevenness of the surface and making it flat, and a common transparent electrode 4 and a common alignment film 6 are formed on the smoothing layer 13. This is a so-called ITO-on-CF configuration substrate. This component board has the advantage that the common transparent electrode 4 is located on the color filter, so the effective voltage applied to the liquid crystal substance 8 does not need to drop, and this component substrate is particularly advantageous in a recently introduced configuration and can be produced at a lower cost. In order to achieve this, there is a movement to form the color filters 1oR, 1oG, and 1oB by an offset printing method.

In addition, in recent years, the STN type has become mainstream for large-area displays such as OA equipment, and by making the cell structure two-layer, it is possible to replace the conventional STN type.
Eliminate the coloring peculiar to TN and enable black and white display,
Various companies have proposed a method of approaching a black-and-white mode by adjusting the difference in refractive index anisotropy of liquid crystals, ΔU, and cell gap d, and a method of replacing one layer of a two-layer cell structure with a film. It goes without saying that the ability to display black and white in the STN mode of the liquid crystal means that it becomes possible to display in color in the STN mode;
This has brought about a major change in the colorization of simple matrices, which were only modes.

Problems to be Solved by the Invention On the other hand, when forming a color filter inside a liquid crystal cell in STN mode and manufacturing an element with an ITO-on-CF configuration, the liquid crystal cell gap (between the common transparent electrode 4 and the segment transparent electrode 3) It is necessary to keep the variation in the distance between the common transparent electrodes 4 to within ±0.05 μm, and for this purpose, it is necessary to flatten the surface irregularities of the common transparent electrode 4 to 0.05 μm or less.

However, as mentioned above, when a color filter is formed using a printing method such as offset printing, the surface unevenness of the color filter is a little over 3 μm, which can be reduced to 0.06 μm.
It is extremely difficult to achieve the following flattening even if we make full use of the selection of the material for the smooth layer 13, the thickness of the smooth layer 13, and the formation method, and it is difficult to make the STN color liquid crystal display element. The problem was that it was difficult. In view of the above problems, the present invention provides a method for forming a color filter for a large-area color liquid crystal display element with high precision, high contrast, and a high viewing angle.

Means for Solving the Problems In order to solve the above problems, a method for forming a color filter for a color liquid crystal display element according to the present invention includes a process in which a color filter printed by offset printing or the like is left in a semi-cured state (B
stage), and then the surface of the color filter is pressed using a press or roller with high flatness accuracy to soften the surface irregularities of the color filter itself.

According to the above structure, the conventional surface unevenness of the color filter 3
Because the surface unevenness is relaxed to half or less than a little over μm, the final surface unevenness (on the alignment film) will be zero in the microwave even if you enlarge it during the selection of the smooth layer material or reduce the forming thickness of the smooth layer material. .05 μm or less, and it is possible to stably and uniformly produce an STN type large area color liquid crystal display element.

EXAMPLES Hereinafter, examples of the color liquid crystal display element of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a color liquid crystal display element according to an embodiment of the present invention, and FIG. 2 is an enlarged view of the main parts thereof. In Fig. 1, 1 and 2 are segments of a liquid crystal cell and a common glass substrate.
r-black matrix 9, RGB color filter 10
R91oG, 1oB are formed by offset printing, 9
Cure for 30-60 minutes between 0° and 110°C to a semi-cured state. The initial surface unevenness at that time is 3pm to 3.6μm.
It is. After that, use a high-precision press or roller to
, suppressed from 6Kp/cd at a pressure of 2 to 6,
The surface unevenness was reduced to 0.6 μm or less, and the product was completely cured at 200° C. for 2 hours. The color filter 10R210G, 10
In order to fill the 0.6 μm unevenness on the surface of B, a smooth layer 1 of novolac epoxy resin P SMX (manufactured by Nippon Kayaku @) was applied.
1 was formed to a thickness of 3 μm to obtain a final surface unevenness of 0°06 μm or less. After that, the ITO-on-CF configuration common substrate on which the transparent electrode 4 and the low-temperature curing alignment film 6 were formed by low-temperature sputtering and the segment substrate were arranged in parallel with each other with a spacer interposed therebetween using a sealant 7, and an STN-type liquid crystal material was added between them. Contains 8. The twist angle of this STN type color liquid crystal display element is 240 degrees, and the display screen size diagonal is 35 degrees.
Although the area was large, 0 m, the uniform alignment and electro-optical properties as a liquid crystal display element were sufficiently satisfactory.

Effects of the Invention As described above, according to the present invention, a color filter is formed on a substrate using an inexpensive printing method, and after semi-curing, it is uniformly pressed with a high-precision press or roller, thereby improving the initial surface irregularities compared to the conventional method. It is possible to easily obtain a final surface roughness of 0.96 μm or less after forming a smooth layer, and it is possible to reliably produce a large-area color liquid crystal display element using an STN type at a high yield. It is something. It should also be noted that surface irregularities of less than f) o os μm can be obtained by using a high-precision press and roller suppression conditions, and an element having a structure without a smooth layer can be produced.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a color liquid crystal display element according to an embodiment of the present invention, FIG. 2 is an enlarged view of the main part of FIG. 1, FIG. 3 is a cross-sectional view of a conventional color liquid crystal display element, and FIG. This is an enlarged view of the main part of Figure 3. 1... Segment glass substrate, 2...
Common glass substrate, 3...Segment transparent electrode, 4...Common transparent electrode, 6...Segment alignment film, 6...Common alignment film, 7...・・・
...Sealing material, 8...Liquid crystal substance, 9...
...Black matrix, 10R, 1oG. 10B...Color filter, 13...
smooth layer. Name of agent: Patent attorney Shigetaka Awano and 1 other person No. 3
Figure 4 1t16 2! 1 mound

Claims (1)

[Claims] (1) A color filter layer is formed by a printing method between black matrix layers formed on a transparent substrate, and when the color filter layer is in a semi-cured state, the surface is pressed to flatten it. A method for forming a color filter for a color liquid crystal display element, characterized by: