JPH02304525A - Manufacture of liquid crystal display panel - Google Patents

Abstract

PURPOSE:To prevent the occurrence of short-circuit between substrates and to improve the manufacturing yield of a panel by superposing the electrode surface of the substrate and a smooth plate, whose surface roughness is lower than that of a panel gap and applying the pressure to them. CONSTITUTION:A smooth glass plate 9 whose surface roughness is lower than that of the panel gap is superposed on the electrode surface of a glass substrate 1a, and they are clipped by a surface plate and the pressure is applied to them by hydraulic pressing machine. Consequently, foreign matters stuck to the surface of the substrate are crushed by the panel gap, and crushed scrap is removed by nitrogen high-pressure injection, ultrasonic washing, or the like. An orienting film 2 is formed on the electrode side of the glass substrate 1a where the pressure is applied, and a sealing member 3 consisting of a thermosetting resin is printed, and SiO2 beads having 2mum particle size are scattered on the other glass substrate 1b as spacers 4. Thereafter, the substrates 1a and 1b are stuck to each other and the sealing member 3 is hardened, and liquid crystal is charged and sealed. Thus, the occurrence of short-circuit between upper and lower substrates is prevented to improve the yield of the panel.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of manufacturing a liquid crystal display panel.

Conventional technology Liquid crystal display devices are used in watches, calculators, word processors, etc. due to their characteristics such as thinness, light weight, and low power consumption.Moreover, with the recent development of information-related equipment, displays with large display capacity and large display area are becoming popular. Demand is increasing.

The structure of the liquid crystal display panel is as shown in FIG. The manufacturing method includes forming 5i on transparent electrodes 7 of a pair of substrates 1.
An insulating film 8 made of 02 is formed, and an insulating film 8 made of
form. Thereafter, the pair of substrates are faced to each other via a spacer 4, and a liquid crystal material 5 is sandwiched between them. A sealing member 3 seals the liquid crystal material 5 between the two substrates 1.

Problems to be Solved by the Invention One of the factors that lowers the yield of the conventional liquid crystal display panel manufacturing process is a short circuit caused by a short foreign object 10 between the upper and lower electrodes 7 as shown in FIG. There are two types of short circuits: short circuits due to conductive substances such as metal powder mixed into the panel during the manufacturing process of the liquid crystal display panel, and short circuits due to foreign matter adhering to the substrate. The former can be prevented by keeping the equipment clean, but the latter can be prevented by cleaning the equipment, etc., but the latter can be prevented by keeping the equipment clean.
It is necessary to remove short-circuit foreign matter). However, since the short foreign matter 10 strongly adheres to the substrate and has a size of several micrometers, it is difficult to remove it by cleaning or high-pressure nitrogen injection, and it is extremely difficult to even check it.

Furthermore, in the case of large-area displays that are in high demand these days, the number of panels that can be produced per substrate is small, and the yield is particularly poor due to the above-mentioned factors.

Furthermore, this tendency is noticeable when a ferroelectric liquid crystal is used. This is because in order for ferroelectric liquid crystals to exhibit their characteristic bistability, the panel gap must be kept below the liquid crystal pitch (generally 0.5 to 3 μm), and nematic liquid crystals Panel gap 5~
This is because even smaller substances than in the case of 10 μm) also cause short-circuit defects.

In view of these problems, the present invention aims to improve the yield of the manufacturing process of liquid crystal display panels.

Means for Solving the Problems In order to solve the above problems, the present invention provides a smooth plate having a surface roughness smaller than the gap between the substrates of a liquid crystal display panel on at least one electrode surface of two substrates having transparent electrodes. Apply contact pressure,
The electrode surfaces of the substrates are arranged to face each other, and a liquid crystal material is sandwiched in the gap.

According to the present invention, by pressing a smooth plate with a surface roughness smaller than that of the panel gap into contact with the electrode surface of the substrate,
Foreign matter adhering to the substrate surface can be crushed to a size smaller than the panel gap. As a result, it is possible to prevent the occurrence of short circuits between the upper and lower substrates, and it is possible to improve the yield of liquid crystal display panels.

EXAMPLE An example of the present invention will be described below with reference to the drawings of FIGS. 1 to 5.

(Example 1) FIG. 1 is a diagram illustrating a pressurizing process according to a first example of the present invention.

First, as shown in FIG. 1a, a glass plate 9 made of the same material as the glass substrate is superimposed on the electrode surface of a glass substrate 1a on which a transparent electrode pattern is formed (the transparent electrode pattern is omitted in the figure). . Thereafter, as shown in Fig. 2, the hydraulic press 12 is used to press the press into a fixed m11 to give a weight of 1 kg/c.
- Apply pressure. Next, as shown in FIG. 1, polyimide resin is printed as an alignment film 2 on the electrode side of the pressurized glass substrate 1a, and then rubbed. Next, a sealing member 3 using a thermosetting resin is printed on this glass substrate 1a, and a particle size 2 is used as a spacer 4 on the other glass substrate 1b.
Sprinkle with μm 5i02 beads. Thereafter, as shown in FIG. 1C, the substrates are pasted together with their electrode surfaces facing each other, the sealing member 3 is cured, and the liquid crystal material 5 is made into a ferroelectric material by using a vacuum injection method from the injection port provided in the sealing member 3. The liquid crystal is injected and sealed to create a liquid crystal display panel. 6 is a sealing resin that seals the injection port.

With the above method, it is possible to crush short-circuit foreign objects between panels by applying pressure, which causes short-circuits between substrates, and eliminate defects caused by foreign object protrusions that lower yields. The yield of panels is dramatically improved to 100%.In this way, most of the short foreign matter is ITO film debris and is soft, so it can be easily reduced to 1 μm or less by applying pressure. Since the remaining debris has been crushed, it can be easily removed by high-pressure nitrogen injection, ultrasonic cleaning, or the like.

In this embodiment, a glass plate was used as the smooth plate having a surface roughness smaller than that of the panel gap, but the same effect can be obtained by using a plate made of stainless steel, iron, etc. whose surface is processed to be smooth. Alternatively, pressure may be applied using a roller 13 with a smooth surface as shown in FIG.

In addition, a pair of glass substrates 1a constituting the liquid crystal panel
+ 1 b can be overlapped and pressurized to obtain the same effect of the present invention, and the number of steps in the pressurizing step can be halved.

A hydraulic press machine was used as a pressurizing method, but Fig. 4a
As shown in Figure 4, the stacked glass substrate and glass plate are placed in a bag and the inside is evacuated to apply pressure using atmospheric pressure, or as shown in Figure 4, pressure is applied using a pressure roller. Any method is fine.

Although ferroelectric liquid crystal was used in this embodiment, the same effect can be obtained using nematic liquid crystal. this is,
This is clear from the fact that the panel gap is larger for nematic liquid crystals than for ferroelectric liquid crystals.

(Example 2) SiO was obliquely deposited as an alignment film, and one glass substrate 1
Print the sealing member 3 on a (.Next, the particle size is 1.5μ).
5i02 beads 15 of m are dispersed and pressurized using the glass plate 9 in the same manner as in Example 1.

Here, for pressurizing the substrate on which the sealing member 3 is printed, a fifth
A glass plate 14 having a cut portion so as not to touch the sealing member 3 as shown in the figure is used. Thereafter, a liquid crystal display panel is manufactured in the same manner as in the first example. Here, 5i02 of 2.0 μm is the same size as the panel gap.
beads are used.

By providing a pressurizing process in the middle of the manufacturing process as in this example, it is possible to crush the conductive material that adhered in the process before the spacer spraying process to a size smaller than the panel gap.
This embodiment is more beneficial than the first embodiment.

Further, in the case where the alignment film has been subjected to alignment treatment, in this embodiment, the alignment treatment is performed by oblique vapor deposition. ) Direct stacking and applying pressure may destroy the membrane. In such a case, if pressure is applied via a spacer having a diameter smaller than the panel gap, the short foreign object can be crushed without damaging the membrane.

Effects of the Invention As described above, according to the present invention, the electrode surface of a substrate having a transparent electrode and a smooth plate having a surface roughness smaller than that of the panel gap are brought into contact with each other and pressurized, or the electrode surface of a substrate having a transparent electrode is brought into contact with a smooth plate having a surface roughness smaller than that of the panel gap, or a spacer smaller than the panel gap is used. By providing a step of overlapping and pressurizing the upper and lower substrates, the occurrence rate of short circuits between the upper and lower substrates can be reduced by one order of magnitude or more compared to the conventional method, and the yield of liquid crystal display panels can be improved.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the manufacturing process of a liquid crystal display panel in one embodiment of the present invention, FIG. 2 is an explanatory diagram showing a pressurizing method using a hydraulic press, and FIG. 3 is an explanatory diagram showing a pressurizing method using a hydraulic press machine. 4 is an explanatory diagram showing another pressurizing method, FIG. 5 is an explanatory diagram showing the pressurizing process in the second embodiment, FIG. 6 is a sectional view of the liquid crystal panel, and FIG. 7 is an explanatory diagram showing the pressing method. is a cross-sectional view of a liquid crystal panel with a short foreign object. la, lb...Glass substrate, 2...Alignment film, 3...Seal member, 4...Spacer, 5...Liquid crystal material , 9...Glass plate, 12...Hydraulic press machine, 13...
・Roller, 14...Smooth plate, 15...
・5i02 beads. Name of agent: Patent attorney Shigetaka Awano and one other person lα, fb
- Glass substrate 2 - Assignment member 3 - Seal member 6 - Aperture m scale 9 - Glass plate! 115! ! Part 21! 1 Volume 4 Atmospheric Wind

Claims (2)

[Claims] (1) A smooth plate with a surface roughness smaller than the gap between the substrates of the liquid crystal display panel is pressed against at least one electrode surface of two substrates having transparent electrodes, and the electrode surfaces of the substrates are arranged to face each other. A method for manufacturing a liquid crystal display panel in which a liquid crystal material is sandwiched between the two. (2) The method for manufacturing a liquid crystal display panel according to claim 1, characterized in that the electrode surface of the substrate and the smooth plate are brought into contact with each other and pressurized through a spacer having a particle size smaller than the gap between the substrates of the liquid crystal display panel.