JPH04204715A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To prevent leakage of the liquid crystals by forming sealing material layers different from each other in components on the corresponding parts on a pair of transparent substrates and allowing each layer to intrude into each other. CONSTITUTION:The sealing material layers 7, 8 different from each other in components are formed on the corresponding parts on the pair of the upper and lower transparent substrates 1, 2 by screen printing or the like, and the substrates 1, 2 are laid on each other and heat pressed, and the lower layer 8 smaller in diameter is hardened while intruding into the upper layer 7 larger in diameter, and at that time, gases are evolved from the interface between the layers 7, 8 to bond the upper and lower substrates 1, 2, thus permitting the obtained liquid crystal display device to prevent cracking between the sealing material 3, 4, even when the sealing layers are enlarged in width and diameter, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a liquid crystal display element, and particularly to a seal structure thereof.

[F-end technology and its problems] Conventionally, liquid crystal display elements have been manufactured by bonding a pair of transparent substrates with transparent electrodes on opposing surfaces separated by a predetermined distance via a rod-shaped sealing material, and filling the gap with liquid crystal. The structure is as follows.

The sealing material used for this liquid crystal display element is made of a thermosetting adhesive, and this thermosetting adhesive is printed on the periphery of one transparent substrate by screen printing, etc., and a pair of adhesives are sandwiched between the adhesives. The pair of transparent substrates are bonded together by overlapping them and heat-treating them in this state to harden the #adhesive. In liquid crystal display elements used in watches and the like, a circular sealing material is provided at the center of the element.

It has been proposed that a through hole is provided through a pair of transparent substrates in order to allow the pointer shaft of a timepiece to pass through the inside of this sealing material.

However, in the liquid crystal display element mentioned above, the width of the sealing material becomes larger than a predetermined value due to the enlargement of both sides, or the sealing material is required to have a through hole through which the hour pointer shaft is inserted. If the diameter of the material becomes larger than a predetermined value, there is a problem in that cracks occur in the sealing material during heat treatment, and liquid crystal leaks through the cracks. It is believed that these cracks are caused by volumetric shrinkage when the sealing material is cured by heat or by gas generation from the sealing material.

That is, when the width of the sealing material is small, the distortion due to volumetric contraction is small, and the generated gas also escapes from both ends of the sealing material in the width direction. However, as the width or diameter of the sealing material increases, the strain due to volumetric contraction increases, and the gas cannot escape from the edges of the sealing material, causing gas to collect in the center of the sealing material and cracking from this area. It is believed that this occurs.

[Object of the invention] This invention was made in view of the above-mentioned circumstances, and its purpose is to provide a liquid crystal display in which cracks do not occur in the sealing material even if the width or diameter of the sealing material becomes large. The purpose is to provide devices.

[Summary of the Invention] In order to achieve the above-mentioned object, the present invention includes a first sealing material provided between a pair of transparent substrates, a first sealing material surrounding the first sealing material, and a second sealing material surrounding the first sealing material. The main point is that the sealing material for joining the pair of transparent substrates is formed by a second sealing material whose components are the same as the material.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 3.

3(A) and (B) show a liquid crystal display element. This liquid crystal display element is used, for example, in timepieces such as wristwatches, and has transparent electrodes ( A pair of transparent substrates l and 2 are provided.
In between, a rod-shaped seal 43 and a circular sealing material 4 are provided, and these sealing materials 3.4 join the pair of transparent substrates 1 and 2 at a predetermined distance apart, and a liquid crystal (
(not shown) is enclosed.

Among the sealing materials 3.4, the rod-shaped sealing material 3 is formed to have a narrow width because the screen of the liquid crystal display element is small. Therefore, the frame-shaped sealing material 3 is formed by using a thermosetting M-adhesive agent on one side of the transparent substrate 1.2 by screen printing or the like.

Note that the frame-shaped sealing material 3 is provided with an injection port 5 for injecting liquid crystal, and this injection port 5 is sealed with a sealant (not shown) after the liquid crystal is injected.

Then, the circular sealing material 4 is provided almost at the center of the liquid crystal display element, and! As shown in 5IWI, it consists of a circular outer sealing material 7 made of the same material as the rod-shaped seal 3, and an inner sealing material 8 made of the same material as the rod-shaped seal 3 inside. A through hole 6 through which a watch pointer shaft is inserted is provided in the center of the watch through the upper and lower transparent substrates 1 and 2. This circular sealing material 4 has a relatively large diameter and is formed as shown in FIGS. 1 and 2.

That is, as shown in FIG. 2, a pair of upper and lower transparent substrates l
, a sealing material layer 7 containing the respective components at the opposing locations of 7.
For example, the sealing material layer 7 provided on the lower surface of the upper transparent substrate 1 is made of the same thermosetting # adhesive as the conventional one, and is formed with a relatively large diameter.

In addition, a sealant J provided on the upper surface of the lower transparent substrate 2
I! F8 is made of a thermosetting conductive adhesive containing QFt (silver paste or carbon paste), has a smaller diameter than the upper sealing material layer 7, and is formed corresponding to its center. Then, the pair of transparent substrates 1 and 2 provided with the sealing material layers 7 and 8 are stacked on top of each other and bonded by thermocompression. Then, as shown in FIG. 1, the lower small-diameter sealing material layer 8 is hardened while biting into the upper large-diameter sealing material M7. At this time, gas escapes from the interface between the sealing material layers 7.8 having different components, and the upper and lower transparent substrates 1.2 are bonded to each other.

Thus, according to the liquid crystal display element described above.

Seal materials 97.8 having different compositions are provided at opposing locations in the central portions of the pair of transparent substrates 1.2, and these seal materials M7.8 are made to bite into each other by thermocompression bonding,
Since the pair of transparent substrates 1.2 are bonded to each other, even if the circular sealing material 4 is directly hit, the sealing material M
7.8 does not shrink in volume when thermosetting and the generated gas does not concentrate in the center, reducing body shrinkage, and sealing material J! ! Since gas escapes from the F7.8 interface, cracks do not occur in the sealing material 4.

Therefore, even if a through hole 6 through which a watch pointer shaft is inserted is provided in the upper and lower transparent substrates 1 and 2 in the sealing material 4, leakage of t& and & can be prevented.

In addition, in the above-mentioned embodiment, a case was explained in which the seal material 4 was applied to a circular seal material 4 through which a pointer shaft of a timepiece was inserted.
The present invention is not limited to this, but can also be applied to a rod-shaped sealing material 3 provided around a liquid crystal display element.

In this way, the present invention can be applied not only to liquid crystal display elements for watches but also to liquid crystal display elements 7 for large screens such as word processors.

[Effects of the Invention] As described in detail, according to the present invention, the true sealing material layers of the components provided at opposing locations of the pair of transparent substrates are allowed to bite into each other. Since the sealing material is configured to cover the transparent substrate, even if the width or size of the sealing material increases, the sealing material will not crack, and leakage of liquid crystal can be reliably prevented.

[Brief explanation of the drawing]

FIGS. 1 to 3 show an embodiment of the present invention, and FIG. 1 shows a sealing material J! having components Jl. ? Fig. 2 is an enlarged sectional view of the W section showing a state in which a pair of transparent substrates are in contact with each other by being bitten into each other. Enlarged sectional view, 3rd
Figure (A) is a plan view of the liquid crystal display element in the state shown in Figure 1, and Figure 3 (B) is its A-Alli plane view. l, 2...Transparent substrate, 3.4...Sealing material. 7.8... Seal material layer. Patent applicant: Casio Calculation Co., Ltd. Figure 1 Figure 2

Claims (1)

[Scope of Claims] A liquid crystal display element in which a pair of transparent substrates having transparent electrodes provided on opposing surfaces are bonded to each other with a predetermined distance separated by a sealing material, and a liquid crystal is sealed in the gap, wherein the sealing material is attached to the pair of transparent substrates. A first sealing material provided between the transparent substrates, and a second sealing material surrounding the first sealing material and having a different composition from the first sealing material. Liquid crystal display element.