JPS6126023A - Production of substrate for liquid crystal display device - Google Patents

Abstract

PURPOSE:To improve the adhesiveness of oriented films formed at a low temp. to substrates in particular and to obviate the generation of a ghost even in display at a high duty ratio by specifying heating conditions in a prescribed range. CONSTITUTION:An arom. polyether amide resin liquid is coated on the glass substrates 3 provided with transparent electrodes 1 consisting of, for example, the oxide of indium and tin and is dried, then the coating is treated at >=150 deg.C and <=250 deg.C to form the orienting material film by which the oriented films 2 are formed. The resulted films 2 have the good adhesiveness to the substrates and have the good orientation characteristic. The electrodes 1 are capable of maintaining low resistance. The high display grade which obviates the generation of the ghost is thus obtainable even in the display at the high duty ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application Akira Honda particularly relates to a method of manufacturing a substrate for a liquid crystal display suitable for driving with a large duty ratio, such as a large-capacity dot matrix.

(Expression) Conventional technology A conventional liquid crystal display has a transparent electrode tin as shown in Fig. 3.
and alignment film f21 T21 substrate for liquid crystal display +3
1 (31) sandwich the liquid crystal (4). In such a liquid crystal display, the resistance value of the transparent electrode (1) t1+ generally increases due to heat treatment.

On the other hand, the alignment film (21) has changed from an inorganic material to an organic material, and the processing has become possible for mass production, but a film formation process is required.
There is an IJ imide-based bulky polymer alignment film, and the minimum film forming conditions are said to be 280°C for 30 minutes, and there are countless references to this type of material. However, baking for 30 minutes at 28D°C naturally affects the transparent electrode (11(1)) and increases its resistance.As a result, in a dot matrix display, the continuous lighting dots can be extended with only about 1/32 duty. A dark half-selected dot-like display (usually called a ghost) appears in the selected dot (usually called a ghost).This ghost is especially noticeable when the duty ratio is large, but the signal waveform is distorted by the resistance of the electrode, especially when the selected dot (lit dot) It is understood that the alignment of the liquid crystal is likely to be disturbed in the vicinity of , so that a ghost appears. However, naturally, the occurrence of this ghost is not desirable because it significantly degrades the display quality.

On the other hand, there are polyamide resins, polyvinyl alcohol resins, aromatic polyetheramide resins, etc. as low-temperature firing type alignment films, but the former two have poor moisture resistance and are not put into practical use. The final aromatic polyetheramide resin was proposed as an alignment agent in JP-A-5B-37621, and was applied as described and dried under heat (100 to 120°C). Although a film was formed, peeling occurred during the rubbing process and production could not be completed.

P→ Problems to be Solved by the Invention The present invention provides a method for manufacturing a substrate for a liquid crystal display in which the adhesion of an alignment film formed at a low temperature to a substrate is particularly improved.

(ii) Means for solving the problem The present invention solves the problem by adjusting the heating conditions among the film forming conditions within a predetermined range. This was done based on the discovery that there is a dependence on

(E) Function This makes it possible to provide a substrate for a liquid crystal display that does not affect the resistance value of the transparent electrode and has a durable alignment film.

(f) Example In explaining the present invention in detail, the characteristics of the transparent electrode will first be explained.

First, to give a concrete example, Fig. 1 is a characteristic diagram of the transparent electrode of a dot matrix display for 1/1[](] duty.
Made of indium and tin oxide, medium length 0.3M2
It shows the relationship between the resistance value at both ends of a 50-fin electrode (covered with an alignment film) and the treatment temperature of 30 minutes of heating. The initial value when forming the pattern is sheet resistance value: 8007 holes and 1.
The average resistance value at both ends was 40Ω. However, 250
℃, the resistance value began to increase, and the resistance value of the electrode of the substrate treated at 280° C. for 50 minutes began to increase rapidly.

Various transparent electrodes were investigated, but it was found that the resistance of all of them increases with a threshold value of approximately 280°C.

Next, the alignment film will be explained. Aromatic polyetheramide resin liquid HL-1100 manufactured by Hitachi Chemical Co., Ltd. (resin concentration 4
%) and some additives were kneaded and applied onto a glass base provided with a transparent electrode using a spinner method at -150 rpm and dried. Figure 2 shows the characteristics of the alignment film made of the alignment agent applied in this way. Density of pinholes (number of pinholes/d) caused by missing alignment film during ultrasonic cleaning
). Although these things were not known in the previous publication, the density of pinholes and the degree of damage and peeling of the alignment film caused by rubbing roughly correspond to three things. In order to prevent damage and peeling, the number should be 10-2 pieces/cd or less, 13 pieces in Figure 2.
It is sufficient if the temperature is 30 minutes or more at 0°C. However, it has been found that the point at which the variation in pinhole density decreases sharply is at 150°C, so processing at a temperature of 150°C or higher significantly improves the yield.

(g) Effects of the invention As described above, the present invention provides aromatic polyetheramide resin
By forming the film at temperatures above 50°C and below 250°C, it has excellent adhesion to the substrate, the alignment properties are as good as before, and the transparent electrode can maintain low resistance, making it suitable for high duty ratio displays. also does not cause ghosting.

[Brief explanation of the drawing]

Figure 1 is a characteristic diagram of the transparent electrode, Figure 2 is a characteristic diagram of the alignment film,
FIG. 3 is a sectional view of the liquid crystal display. tl) (11...Transparent electrode, +21 (21...Alignment film, +31 (3)...Substrate, (4)...Liquid crystal.

Claims (2)

[Claims] (1) An alignment agent is provided on a substrate having a transparent electrode, and
A method for manufacturing a substrate for a liquid crystal display, characterized in that an alignment film is formed by forming an alignment agent by processing at a temperature of not less than 0.degree. C. and not more than 250 degrees Celsius. (2) The method for manufacturing a substrate for a liquid crystal display according to claim 1, wherein the alignment film is made of an aromatic polyetheramide resin.