JPS59232315A - Production for liquid crystal display element - Google Patents

Abstract

PURPOSE:To improve the uniformity and the precision of a cell gap by hardening a sealing layer in the state where the pressure in a sealing body of a liquid crystal display element is made lower than that in the outside of the sealing body. CONSTITUTION:A sealing body 6 where a sealing layer 5 is not hardened yet is so attached that a notched part 8 is grasped by a vacuum chuck 9, and air in the vacuum chuck 9 is discharged to reduce the pressure in the part of a cell gap 7. Elastic bodies 10 and 11 consisting of rubber or the like are provided in the parts of the vacuum chuck 9 to which the sealing body 6 is attached, and such airtightness is held that a prescribed pressure reduction is kept. Since the sealing body 6 in this state has the sealing layer 5 hardened in the state where its outside overall surface is depressed uniformly with a high voltage (normal air pressure) vertically, the high-uniformity cell gap 7 is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (11) Technical Field of the Invention The present invention relates to a method for manufacturing a liquid crystal display element, particularly for manufacturing a liquid crystal display element that requires high cell gap accuracy, such as a matrix drive liquid crystal display element. The present invention relates to an assembly method suitable for.

(Background of BL technology) Due to the characteristics of liquid crystal display elements, such as low voltage, low power consumption, and being a light-receiving display element, their application range is wide-ranging. Along with this, they are also being used in various terminal devices and office automation (OA) devices.

The thickness of the liquid crystal layer in such a liquid crystal display element, that is, the interval between electrodes (cell gear) provided on the surfaces of two substrates constituting the liquid crystal element, is usually 8 to 1 (b!m).
Depending on the drive response speed of the display element or the type of electro-optic effect used for display, the cell gear knob value will affect the drive voltage (more precisely, the threshold voltage), and its variation will affect these drive characteristics. causing variations in
Furthermore, when interference colors are involved, color unevenness occurs.

As a result, there are constraints on the display capacity (i.e., the amount of display bits determined by the number of driveable electrodes), display area, or W changing speed of the display screen, and a decline in display quality. This causes an increase in cost 1- due to stabilization of the drive circuit. Therefore, making the cell gap uniform is an extremely important issue for practical use of liquid crystal display elements.

The biggest cause of variation in cell gears is the non-uniformity that occurs during the manufacturing of liquid crystal display elements, more specifically when two substrates are sealed together.In order to eliminate this, each manufacturer uses various know-how. are multiplied by N.

fc) Prior Art and Problems Below, an overview and problems of a method for assembling a liquid crystal display element and a conventional sealing method will be explained.

A first substrate (glass plate) 2 on which, for example, an X electrode group 1 as shown in FIG. 1(A) was formed, and a first substrate (glass plate) 2 on which, for example, an A second substrate (glass plate) 4 is prepared and subjected to a predetermined treatment such as surface orientation treatment. For example, a sealing layer 5 made of a resin adhesive or the like is applied to the surface of the second substrate 4, The end plates 2 and 4 are assembled facing each other with a predetermined gap maintained therebetween, and the sealing layer 5 is cured to form a sealed body 6 as shown in FIG. The same figure (C) is a schematic diagram showing the LL cross section of the same figure (B), and the liquid crystal is filled in the cell gap 7. Note that the sealing layer 5 in the same figure (B) The cutout portion 8 is temporarily provided to form a liquid crystal passage during filling.

A spacer (for example, a piece of glass fiber with a diameter of about 8 μm) is mixed in the current-carrying and sealing layer 5 to maintain the cell gap, and the layer thickness immediately after coating is made larger than a predetermined cell gap value.

Then, in the step of curing the sealing body 6, a pressing force is applied to both end plates 2 and 4 from both sides to the entire surface or only the peripheral portion thereof, and the end plates 2 and 4 are pressed and pressed until they are mutually supported by the spacer. A predetermined cell gap is obtained by each step. Note that spacers similar to those described above are also placed in the cell gap portion using an appropriate method.

In this case, the conventional pressurizing method has been to use a press or a lip as shown in FIG. Such a pressurizing method has the disadvantage that sufficient cell gap accuracy cannot be obtained. The main reason for this is thought to be as follows.

That is, i) since the substrate 2 or 4 is not completely flat, it is not pressed in perfect surface contact with the press machine, resulting in uneven distribution of pressing force, and in the sealing layer 5 portion, both end plates only have spacers. ii) Because the parallelism of the opposing pressing surfaces of the press is not sufficient, the substrates 2 and 4 are not pressed so as to remain parallel to each other and are tilted. iii) In the case of applying pressure using the crimp, only the peripheral parts of both end plates are pressed, so the force that causes the central part to warp outward is not exerted, and for this reason, the cells in the central part This causes the gap to become larger and the sealing layer to be hardened.

(diObject of the Invention) The present invention aims to eliminate the cause of the drawbacks of the above-mentioned conventional methods regarding the non-uniformity of the cell gap that occurs during the formation of a sealed body of a liquid crystal display element. The purpose of the present invention is to disclose a sealing method that can improve properties.

(e1 Structure of the Invention The present invention provides a sealed body consisting of two substrates placed facing each other and a sealing layer coated around the gap formed by the two substrates in the assembly of a liquid crystal display element. It is characterized in that the It adhesion layer is cured under a state where the pressure inside the inside is lower than that outside the outside, and as a specific means, it has a diagonal curved surface whose interval can be freely changed depending on the pressure difference between the inside and the outside. The sealed body was housed inside an airtight container provided with two plate-shaped bodies, and the inside of the airtight vessel was made to have a negative pressure, and the two substrate surfaces of the sealed body were placed in the plate-like shape of the airtight container. The sealing layer is cured when pressed between opposing surfaces of the body, and an example of the airtight container is an airtight bag-like container made of a thin flexible sheet. .

ff) Examples of the invention Embodiments of the present invention will be described below with reference to one drawing.

In the following drawings, the same parts as in the previously published drawings are denoted by the same reference numerals.

FIG. 3 shows a first embodiment of the sealing method of the present invention, (A
) is an external perspective view, and (B) is a sectional view.

That is, as shown in FIG. 3, the sealed body 6 assembled as shown in FIG. In this manner, the inside of the vacuum chunk 9 is evacuated and the pressure in the cell gap 7 is reduced.

Elastic bodies 10 and 11 made of rubber or the like are provided in the sealing body G holding portion of the vacuum chuck 9 to maintain airtightness to the extent that a predetermined reduced pressure can be maintained.

The sealed body 6 in the state described in item 2 is vertically and uniformly pressed on its entire external surface with high pressure (usually atmospheric pressure). Since the sealing layer 5 is cured in this state, a highly uniform cell gap 7 can be obtained. In order to accelerate the curing of the sealing layer 5 and increase its fluidity before curing, it is necessary to make it easier for the side substrates 2 and 4 to face each other only through the spacer in the sealing layer portion. The sealed body 6 is heated accordingly, but even in the case of the configuration shown in FIG. 3, there is no risk of any particular difficulty in heating the sealed body 6 and the vacuum chuck 9 as a whole.

FIG. 4 shows a second embodiment of the present invention, and as shown in FIG. The 1/1 attached body 6 shown in FIG.
After storing the container, the inside of the airtight container is depressurized. Since the plate-shaped bodies 12 and 13 of the airtight container are in a state where they can be freely displaced, the sealing body 6 tries to come into close contact with each other due to external pressure.
are pressed from both outer surfaces so that they are parallel to each other.

2, by installing an elastic body 16 such as a rubber plate between the sealing body 6 and each of the plate-like bodies 12 and 13, the flat surface of the substrates 2 and 4 or the plate-like bodies 12 and 13 is It is possible to compensate for the unevenness and damage of the pressure, and to make the distribution of the pressing force on the sealed body 6 uniform. Also in the method of this embodiment, there is no risk of any particular difficulty in heating the sealed body 6.

Note that a bellows made of rubber or metal is suitable as the flexible member 14, and one end of the flexible member 14 is connected to one of the plate-shaped bodies 12 and 13, as shown in FIGS.
For example, an annular member 141 that fits into an annular groove 121 provided around the plate-shaped body 12 is hermetically sealed. In the above configuration, when the inside of the airtight container is depressurized, the annular groove 1
The required airtightness is maintained at the contact surface between 21 and the annular member 141. The annular groove 121 and the annular member 141 as necessary.
An 0-ring seal may be used between.

FIG. 5 shows a third embodiment of the present invention, in which the sealed body G is housed inside a bag-like airtight container 15 made of, for example, a polyester film, and then the pressure inside the bag-like airtight container 15 is reduced. In this state, the sealed body 6 is completely sealed with the bag-like airtight container 15, and is pressed uniformly over the entire surface by external pressure. Even in the method of this embodiment, there is no risk of causing any particular trouble regarding the heating of the sealed body 6, and the bag-like airtight container 1
5 is sealed at the υ1kiro X-X part and the exhaust system is not cut, making handling easier.

The effects of the above embodiment will be explained by giving numerical examples.

As a substrate, width 32mm, length 30+nm, thickness 1.1
After forming an orientation control film on the surface of a glass slope with a transparent conductive film of 100 mm thick, an epoxy sealant mixed with 8 μm glass fiber was applied to one of the substrates using a printing method. Glass fibers having the same diameter as above were distributed on the other substrate, and the respective substrates were stacked together to form a sealed body (1).

The sealed body was stored in a polyester bag, and the whole was placed in a vacuum device and evacuated. After sealing the bag at a pressure of 1/100 Torr, The whole bag was taken out while the bag was still open, and the sealed body was heated in a heating device to harden the sealant.

We took out the IJ garment from the bag, selected 1024 locations inside the arrival part, and measured the cell gap.As a result, the average value of the cell gap was 8.7. +1m, standard deviation σ-0,13
◇ On the other hand, using the same substrate and arrival agent as above, after assembly, two glass plates with a thickness of 3 mm were applied to the outside of each substrate, and the surrounding area was shown in Figure 2. As a result of performing the same measurements as above on the sealed body obtained by the conventional method, which was obtained by heating the sealing agent in a heating device while being held between the two clips shown and pressurized, the cell gap was The average value was 9.0 μm and the standard deviation σ-0.24 μm.

In the above conventional method, the measurement results for the sealed body obtained when the number of glass plates applied to the outside of each substrate was set to 3 were the average cell gap of 9.0.
μm, standard deviation σ-0.32 μm.

As described above, the present invention makes it possible to uniformly press the entire surface of a liquid crystal surface element when sealing it, regardless of its area. It is clear that it is particularly effective in manufacturing liquid crystal surface elements, and also in the case of small liquid crystal display elements.
It has the advantage of being able to seal a large number of elements at once and improving productivity.

(g1) Effects of the Invention According to the present invention, liquid crystal display elements for high-density dynamic drives that require particularly high precision and uniform cell gap, or guest displays using dichroic dyes,
It is effective in the practical application of host-type liquid crystal display elements, etc., and has the effect of making it possible to provide a liquid crystal display element having high-speed response characteristics and large display capacity necessary as a display element of a display device of a terminal device or a device.

[Brief explanation of the drawing]

Fig. 1 is a diagram for explaining the structure of a liquid crystal display element and an overview of the structure of the 1/1 bonded body, and Fig. 2 is a diagram showing an example of a pressurizing device conventionally used for applying pressure during sealing. , FIGS. 3 to 5 are diagrams showing an embodiment of the sealing method according to the present invention. In the figure, ゛(, ■ is the X electrode group, 2 is the first substrate, 3 is the Y
fIi pole group, 4 is the second substrate, 5 is the sealing layer, 6 is the sealing body, 7 is the cell gap, 8 is the notch part, 9 is the direct air chuck, 10, 11 and 16 are the elastic bodies, 12 13 is an opposing surface, 14 is a flexible member, 15 is a bag-like airtight container, 121 is an annular groove, and 141 is an annular member. 1st/l 2nd delivery

Claims (3)

[Claims] (1) When assembling a liquid crystal display element, the inside of a sealed body consisting of two substrates placed opposite to each other and a sealing layer coated around the gap formed by the two substrates is viewed from the outside. A method for manufacturing a liquid crystal display element, characterized in that the sealing layer is cured under a low pressure. (2) After storing the sealed body inside an airtight container provided with two plate-shaped bodies having opposing surfaces whose distance can be freely changed depending on the pressure difference between the inside and outside, the inside of the airtight container is Claim 1, characterized in that the sealing layer is cured under negative pressure and the two substrate surfaces of the sealing body are pressed between opposing surfaces of the plate-like body of the airtight container. A method for manufacturing the liquid crystal display element described above. (3) The method for manufacturing a liquid crystal display element according to claim 2, wherein an airtight bag-like container made of a thin flexible sheet is used as the airtight container.