JPS63163423A - Manufacture of liquid crystal display device - Google Patents

Abstract

PURPOSE:To impress a uniform pressure by pressing on a seal by an annular elastic body, using this elastic body as a seal ring, and impressing a gas pressure to a space surrounded by its holding member and a cell. CONSTITUTION:An annular elastic body 20 positioned on a seal 17 of a cell 19 placed on a base 21 is fitted into a seal ring groove provided on a holding member 22 of this elastic body, and the cell 19 is pressed on the seal. To a space 24 surrounded by the cell 19, the annular elastic body 20 and the holding member 22, a gas pressure 26 is impressed from the outside through a breather 25. In this state, the seal is hardened by heating or irradiation of ultraviolet rays, etc., and from its injection port, a liquid crystal is injected in a vacuum and the port is sealed, and thereafter, by sticking a polarizing plate to the surface and the reverse side, a finished liquid crystal cell is formed. In such a way, a cell of high accuracy, which scarcely has a variance and ununiformity of the cell thickness is obtained easily.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing a liquid crystal display device, and more particularly to a method for bonding two substrates together.

Conventional technology A method for manufacturing a liquid crystal display device in which liquid crystal is sealed between two electrode-attached substrates is to bond two substrates together, such as bonding one substrate with an adhesive applied to the sealing turns and the other substrate. Layer them together via spacers and use weights! A common method is to heat and cure the seal adhesive while applying pressure to 12 substrates. FIG. 6 shows an explanatory diagram of such a conventional bonding method, in which a sealing adhesive 3 containing a spacer material is applied to one of the two electrode-attached substrates 1 and 2. Cells 5 stacked one on top of the other with spacers 4 interposed therebetween are stacked alternately with sheets 6, and a load 8 is applied with a spring or weight via a suppression board. In this state, the entire temperature is raised to heat and harden the seal adhesive 3.

Such a method causes variations in the uniformity of the pressure applied to the cell 5, and therefore there is a limit to the thickness accuracy of the cell gap. Particularly for large-area liquid crystal display devices and active materials that undergo a multilayer thin film process and have large substrate warpage)
In the case of J-wax liquid crystal display devices, this is an even bigger drawback. FIG. 7a shows an example of a conventional pressurizing method that improves this point. For example, instead of using a heat-resistant polyimide sheet 6, a pressure plate 7 presses a cell 5 through a silicone rubber block 9 to apply a load of 8. Add. Even in such an example in which the uniformity of the pressure applied to the cell is improved, the pressure distribution becomes 1o as shown in Figure 7, and the load applied to the seal 3 located around the substrate is smaller than that at the center, and the seal When the adhesive is highly adhesive, the cell gap can only be narrowed to a predetermined gap determined by the spacer material mixed in the sealing adhesive, making it difficult to obtain uniformity of the gap.

Problems to be Solved by the Invention In contrast to the conventional technology, the present invention provides a new method for bonding two electrode-attached substrates, and realizes a highly accurate cell with less variation and non-uniformity in cell thickness. Therefore, it is an object of the present invention to provide a manufacturing method for realizing a liquid crystal display device having high contrast and high quality image quality performance with little vortex unevenness. Although the drawbacks of conventional bonding methods are as described above, the present invention is particularly effective in manufacturing methods for simple matrix or active matrix liquid crystal display devices for large-area, high-definition image display. In devices, the key to achieving high image quality is the ability to achieve high gap accuracy, and it was not possible to achieve satisfactory viewing and display performance using conventional bonding methods.

The present invention is particularly designed to meet the suppression conditions of the seal located around the cell, and to butt two electrode-attached substrates with warpage and ridges along the spacer material to a high precision of 5 degree. The purpose of this project is to solve these problems based on the technical idea that there are independently optimal suppression conditions for each suppression condition.

Means for Solving the Problems The present invention adopts the following configuration in order to solve the above problems. That is, in a method of manufacturing a liquid crystal display device in which a liquid crystal is sealed between two substrates with electrodes with a seal, a step of applying a sealing adhesive containing a spacer material to one of the substrates, and a step of applying a sealing adhesive containing a spacer material to one of the substrates; and a step of hardening the seal while pressing the stacked cells, and a ring-shaped elastic body that presses on the seal as means for pressing and holding the cells, and It is characterized by having a holding member that holds the elastic body and a means for holding the cell in a pressed state, and applying gas pressure to a space surrounded by the elastic body, the holding member, and the cell. be.

In particular, as an example of this application, as a method of applying gas pressure, a gas is filled in a sealed space surrounded by the elastic body, a holding member, and a cell, and thermal expansion of the gas generated by heating these is used. Pressure can be applied to the cell.

Function: As described above, as a method of pressurizing two electrode-attached substrates, the seal is pressed with an annular elastic body, and this elastic body is used as a seal ring to apply gas pressure to the space surrounded by this holding member and the cell. By doing this, the pressing conditions on the seal are the suppression conditions of this annular elastic body, and the inside of the cell screen can independently set the optimal conditions by gas pressure, and the two electrode-attached substrates with complicated warps and undulations can be set independently. It is possible to apply uniform pressure along the spacer, which is ideal for aligning the gap with high precision.

In particular, when applying the gas pressure using the thermal expansion of the gas in the closed space surrounded by the elastic body, the holding member, and the cells, it is possible to realize a compact pressure jig for curing the bond. By heating the cell together with the jig, gas pressure can be automatically generated during heat curing of the seal, which is convenient.

Example Next, the present invention will be described in detail according to examples of the present invention.

FIGS. 6a, b, and C show a combination of two electrode-attached substrates (a and b) and a part of the method for manufacturing an active matrix type liquid crystal display device for color image display according to the present invention. A liquid crystal cell C is shown. As shown in FIG. 6d, the substrate surface of one electrode-attached substrate 11 is vapor-deposited,
Pixel elements for image display and thin film transistor elements serving as switching elements are fabricated by photofabrication technology to form the multi-screen 12. A large number of extraction electrodes 13 for scanning and signals of image signals are formed around the screen, and an alignment film 4 is applied to cover the screen. As shown in FIG. 6, the electrode-attached substrate 16 on which the other color filter is formed is also coated with an alignment film covering the entire surface of the transparent electrode, and a sealing adhesive containing a spacer material is applied around this. , part of which is inlet 1
8, it is applied in an open seal pattern.

These two electrode-attached substrates 11 and 15 are stacked on top of each other with the alignment film on the inside via a spacer to form a liquid crystal cell 19 shown in FIG. 6C.

FIG. 1 shows a state in which a cell 19 according to an embodiment of the present invention is bonded and pressed. FIG. 3 shows a plan view a and a cross-sectional view of the annular elastic body 20 used for this bonding and pressing. As shown in FIG. 1, the annular elastic body 2o located above the seal 17 of the cell 19 placed on the base 21 is fitted into the sealing groove provided in the holding member 22 of this elastic body.
Cell 19 is pressed onto the seal. (Means for pressurization and clamping are not shown.) Gas pressure 26 is applied from the outside through a vent 25 to the space 24 surrounded by the cell, the annular elastic body, and the holding member. In this state, the seal is cured by heating or ultraviolet irradiation, liquid crystal is injected through the injection port in vacuum, the seal is sealed, and polarizing plates are attached to the front and back surfaces to form a completed liquid crystal cell.

Note that the load on the seal is different when the seal is pressed by an annular elastic body without applying gas pressure, and when gas pressure is applied. That is, when gas pressure is applied, the reaction force that the holding member receives due to the gas pressure acts on the seal in a direction that reduces the pressing force.

FIG. 2 shows a thermal expansion type pressurizing jig showing a second embodiment of the present invention, in which an annular elastic body 20 is fitted into a sealing groove 28 provided in a holding member 27 to seal the seal 19. This elastic body 20 presses on 17. The two holding members 27 are held in a clamped state by a support bolt 29 and a nut 3o via a spring 31. Stainless steel is used for the holding member and the support bolt, and silicone rubber is used for the annular elastic body.The seal is thermally hardened by placing the assembly in a heating furnace with the press jig shown in FIG. 2 installed. Due to this heating, the dry N2 filling the space 32 surrounded by the cell 19, the holding member 27, and the annular elastic body 2o thermally expands, and gas pressure is applied to the liquid crystal cell 19. At this time, the 10 vanes made of pressed silicone rubber tend to increase as the temperature rises, but this can be offset by selecting the rigidity of the spring 31. Figure 4 shows experimentally verified data on the internal pressure of the pressurizing jig shown in Figure 2, and shows the internal pressure and jig temperature (
A change in the temperature of the holding plate over time of 0.4 atm was actually measured. A seal bonding experiment was carried out with the initial load applied to the silicone rubber set at 5 KP, and the cell gap accuracy after liquid crystal injection was examined, and gap uniformity within ±0.2 μm was obtained.

When air with a humidity of 50% was used as the filling gas, the actual internal pressure was 0.86 atm, which was an increase in pressure that was thought to be due to water vapor pressure.

As a further improvement to this manufacturing method, a relief valve communicating with the closed space may be provided to control the gas pressure so that it does not rise above a certain pressure.

As can be seen from the effects of the invention, according to the manufacturing method of the present invention, it is possible to apply a uniform and stable pressing force with an ideal load distribution within the sealing part and the screen when bonding 11 vane cells. High-precision cells with very little variation or non-uniformity in cell thickness can be easily obtained, and a liquid crystal display device with excellent display performance can be provided, which is of great industrial value.

[Brief explanation of the drawing]

FIG. 1 is an assembled cross-sectional view showing an embodiment of the method for manufacturing a liquid crystal display device of the present invention, FIG. 2 is an assembled cross-sectional view showing a second embodiment, and FIG. FIG. 4 is a plan view and side sectional view of an annular elastic body; FIG. 4 is a characteristic of experimental data in the same manufacturing method; FIG. 7 and 7 are assembled sectional views showing a conventional example. 11...Substrate with electrode (array substrate with TFT),
15... Substrate with electrode (color filter substrate),
17...Seal, 19...Liquid crystal cell,
20...Annular elastic body, 22.27...
Holding member. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 5
Iconography) 1.3 JP-A-63-IG3423 (6) Figure 6 Figure 7 - Drawing ≦N, Pen

Claims (3)

[Claims] (1) A method for manufacturing a liquid crystal display device in which liquid crystal is sealed between two electrode-attached substrates with a seal, including the steps of: applying a sealing adhesive containing a spacer material to one of the substrates;
The process includes a step of stacking two electrode-equipped substrates via a spacer means, and a step of hardening a seal while pressing the stacked cells. It has an elastic body, a holding member that holds the elastic body, and a means for holding the cell in a pressed state, and applies gas pressure to a space surrounded by the elastic body, the holding member, and the cell. A method for manufacturing a liquid crystal display device. (2) A jig in which the seal adhesive is a thermosetting adhesive, and has an annular elastic body that presses on the seal, a holding member that holds this elastic body, and a means for holding and holding the cell in a pressed state. By incorporating the cell into the cell and heating the jig together, the seal is hardened while applying pressure to the cell due to the thermal expansion of the gas that fills the sealed space surrounded by the imager, the holding member, and the cell. A method for manufacturing a liquid crystal display device according to claim 1, characterized in that: (3) The method for manufacturing a liquid crystal display device according to claim 1, characterized in that a relief valve that operates at a constant pressure is provided between the closed space and the atmosphere.