JPH0436366B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method for manufacturing a liquid crystal display element, and particularly to a method for sealing an injection port.

[Background of the invention]

Conventional methods for sealing the filling port of liquid crystal display elements include (a) making a hole perpendicular to the substrate surface, introducing the liquid crystal through the hole, filling the hole with a soft metal such as indium (In), and then A method of sealing with adhesive etc.

(b) A method in which a part of the side surface of the sealant and substrate is cut out, a soft metal such as indium is pushed into this, and the top is sealed with adhesive.

(c) A method is to cut out a part of the sealing material, provide a vapor-deposited layer of Ni, Cr-Au, etc. as a base layer for soldering on the side of the board, and then solder it to the glass after filling the liquid crystal for sealing. be.

However, the conventional method as described above has the following problems.

(a') When making a round hole in the substrate and filling it with indium, etc., the liquid crystal at the sealing opening is pushed into the element, which may cause the package to break during sealing due to Pascal's principle, or the element may have an outwardly convex shape. This makes it impossible to maintain uniform cell spacing. As a result, the response speed becomes partially non-uniform and the cell spacing is non-uniform, resulting in DAP (deformation of
This has the disadvantage that coloring occurs due to the aligned phases, making it very difficult to see.

(b') In the case where a part of the sealing material and the side of the board is cut out and a soft metal is pressed into the cutout, the seal is sealed.
Since it is like a wedge of soft metal is inserted between the two substrates, the package is also likely to break during the sealing process. In addition, it is very difficult to stuff indium or the like into a small hole on the side of the element.

(c') When a soldering base layer is created on the sides of the two boards after sealing and soldered after the liquid crystal is sealed, there is no damage to the package as described above, and the sealing port can always be sealed stably. This is a very reliable and industrially superior method that does not cause any liquid crystal leakage, but since the liquid crystal is directly heated above the melting point of the solder, depending on the type of liquid crystal, the liquid crystal may thermally decompose. This may lower the N-I point near the sealing opening or cause decomposition products to adhere between the soldering base layer and the solder and hinder soldering.
It had drawbacks such as leakage.

Compared to these, when sealing an element like (c) above with only adhesive, there are no drawbacks like (a'), (b'), and (c') above, and the workability is good. There is no damage to the package or decomposition of the liquid crystal, and there is no leak phenomenon where liquid crystal leaks from the package.
Since it is a very good method industrially and has stable workability, its widespread use has been desired, but it has the following drawbacks, so there are still very few methods that have been put into practical use. It was hot. When sealing an element using an adhesive (e.g. epoxy adhesive) using a partially cut out part of the sealing material as a sealing opening,
Generally, adhesive is applied to the sides of the two substrates where the sealing opening is located to a height of 1 mm or less for sealing. Since the encapsulating material of an element constructed in this way is organic, it is generally moisture permeable and hygroscopic, and when the liquid crystal display element is placed in a high humidity atmosphere during actual use, the encapsulating material will not pass through the element. Moisture often causes the liquid crystal in the package to be hydrolyzed, resulting in poor phenomena such as a decrease in the N-I point of the liquid crystal, a decrease in impedance, poor alignment, and display unevenness.

In addition, if an attempt is made to thicken the sealing adhesive layer to prevent moisture permeation, the height of the sealant must be approximately 3 mm, and the appearance of the liquid crystal element requires a small and thin design. In addition, it was inconvenient for mounting small devices such as wristwatches.

[Purpose of the invention]

The present invention aims to provide a new method for sealing the filling opening of a liquid crystal display element using an adhesive, which eliminates the above-mentioned drawbacks, has good workability, does not cause package damage or leakage, and prevents deterioration due to moisture permeation. It is something.

[Summary of the invention]

The present invention involves sealing the periphery of two electrode substrates facing each other with a certain gap between them with a sealing material, making a notch in a part of the sealing material, and using this as an injection port to insert the liquid crystal between the substrates and the sealing material. In a method for manufacturing a liquid crystal display element, in which a sealed space is filled and then the sealing opening is sealed with a sealing material such as an adhesive, the sealing material is placed between a notch of the sealing material and two electrode substrates. It is concerned with a method of sealing the sealing port that penetrates into the sealing port formed by the area surrounded by .

[Embodiments of the invention]

The present invention will be explained below using the drawings.

FIG. 1 is a front view and a side view showing a liquid crystal display element according to the present invention. 1 is an upper substrate, 2 is a lower substrate, and on the opposing inner surfaces of each substrate are transparent electrodes (not shown) formed with, for example, indium oxide, tin oxide, etc., using a method such as print etching, photoetching, or printing. ) and are arranged facing each other with a predetermined distance between them with a sealing material 3 around them as shown in the figure. Generally, in order to separate and hold two substrates for a predetermined period of time, a substance with a uniform diameter, such as glass fiber or glass beads, is mixed into the sealing material 3, and one substrate is attached using a method such as screen printing. After printing, the two substrates are bonded together and heat cured or heat melted to join the substrates 1 and 2 with a predetermined distance between them.

A part of the sealing material 3 has a notch for sealing the liquid crystal and for removing gas such as air in the space surrounded by the substrate and the sealing material 3 at the time of bonding the two substrates. and a sealing port 6 surrounded by a sealing material.

Further, upper and lower connection points 9 for connecting the electrodes of the upper substrate 1 and the electrodes of the lower substrate 2 are provided in a part of the sealing material.

For example, about 70 pieces of package formed in this way
The liquid crystal 5 is heated in a predetermined atmosphere at ~80℃.
Thereafter, the sealing opening is sealed using a sealing adhesive 4 while the element filled with liquid crystal remains heated.

After applying the adhesive 4 to the sealing port 6 in such a heated state, when the device is cooled to room temperature, the thermal expansion coefficient of the liquid crystal material is generally larger than that of the upper and lower substrates made of glass, etc., so it shrinks and the sealing port The liquid crystal at 6 enters the element, and in response, a portion of the adhesive 4 enters the sealing opening 6 to form a sealing material 7. After reaching this state, use adhesive 4
The sealing of the sealing port is completed by curing.

FIG. 2 is a front view and a side view showing another embodiment of the liquid crystal display element according to the present invention, and the same parts as in FIG. 1 are designated by the same reference numerals. Generally, when the size of the liquid crystal display element becomes large, the liquid crystal material 5 is
Since the difference in volumetric contraction due to the difference in thermal expansion coefficient between the upper and lower substrates increases, the amount of sealing material 7 that enters into the sealing port 6 increases. Therefore, the sealing material 7 is
Since the sealing material 7 enters the element in a fan-shaped shape with the center at the center, if there is a large amount of the sealing material 7, there is a possibility that the sealing material will penetrate into the display area and interfere with the display. In such a case, a stopper such as a partition wall 8 made of the same material and formed by the same method as the sealing material shown at 8 in FIG. 2 is provided in advance to prevent the sealing material 7 from penetrating into the display area. be able to.

〔Effect of the invention〕

In the liquid crystal display element manufactured as described above, the sealing material penetrates by a width equal to or greater than the sealing material width of 10, so the moisture resistance when placed in high humidity is lower than that of the conventional sealing structure. Significantly improved compared to .

For example, in a forced deterioration test at 70°C and 95% RH, it was found that the moisture resistance performance was improved by about 6 times compared to an element in which adhesive did not penetrate between the elements. In addition, when sealing the sealing port with such an adhesive, there is no forced pressure applied from the outside, so there is no damage to the package during the sealing port sealing process.
The liquid crystal does not thermally decompose, the workability is simple, and the moisture passing through the sealing material during its life can be extremely reduced, so it has the excellent effect of not causing deterioration due to moisture intrusion.

[Brief explanation of drawings]

FIG. 1 is a front view and a side view of a liquid crystal display element showing an embodiment of the invention, and FIG. 2 is a front view and a side view showing another embodiment of the invention. 1, 2... Substrate, 3... Sealing material, 5... Liquid crystal, 6... Sealing port, 7... Sealing material.

Claims (1)

[Claims] 1. A liquid crystal display element in which the peripheries of two opposing electrode substrates are sealed with a sealing material, a partially cutout part of the sealing material is used as a filling port, and liquid crystal is filled, and then the filling port is sealed with a sealing material. In the manufacturing method, after filling the liquid crystal in a heated state, a sealing material is applied to the sealing hole in a heated state, and the element is cooled to room temperature, so that the sealing material is introduced into the filling hole, and then hardened to perform sealing. A method for manufacturing a liquid crystal display element, characterized by: