JP2942431B2 - Liquid crystal display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device used for various electronic devices such as office automation devices, and more particularly to a liquid crystal display device made of a resin substrate.

[0002]

2. Description of the Related Art For example, in recent office automation equipment, there has been a demand for a thinner and lighter liquid crystal display device corresponding to a lighter and smaller size such as a notebook size and a palmtop size.

[0003] A resin substrate has been used as a substrate of a liquid crystal display device for achieving a reduction in thickness and weight of the liquid crystal display device.

[0004]

When a resin is used as the substrate, the liquid crystal display can be made thinner and lighter, but the resin substrate has a low shielding property against gas, water and the like. There was a problem.

Therefore, a resin layer of polyvinyl alcohol (hereinafter referred to as PVA) or the like is formed on a resin substrate to improve the shielding property.

However, even when a resin film made of PVA is formed on a resin substrate made of polyether sulfone, for example, the gas (O ₂ ) barrier property is about 0.5 cc / m ^{2 at} 40 ° C. and 95% RH.・ 24Hr ・ Atm, water (H
_{Since the} moisture permeability of ₂ O) is several g / m ² · 24Hr, it cannot be said that the shielding property is good, and the temperature is 40 ° C. and 95% RH.
Under the condition (1), there is a problem that water, O _{2, and the} like enter the cells of the liquid crystal display device, bubbles are generated in the liquid crystal layer, and the display quality deteriorates.

In addition, the present inventors have proposed in Japanese Utility Model Application No. 3-70458 to improve the display quality by forming a single layer film of SiO _{2 on} the surface of a resin substrate. No mention was made of cracking.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional drawbacks, and has been made in view of the above. A liquid crystal having a liquid crystal layer interposed between a pair of transparent substrates made of resin. In the display device, a laminated film of SiN _x and SiO _x is formed on both surfaces of the pair of transparent substrates , and the SiN _x is a transparent substrate.
In order to improve the adhesion of the plate interface, the transparent substrate and the
It is characterized by being formed between SiO _X.

[0009]

According to the present invention, SiN _x is made of a transparent substrate and SiO _x
Is formed between the SiN _x
Nitrogen plasma required when forming by the
Clear adhesion at the transparent substrate interface without damaging the substrate surface
Performance can be improved. Therefore, on the SiO _X
Can Rukoto improve the crack resistance of a transparent electrode formed.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a liquid crystal display device 1 showing one embodiment of the present invention. A pair of transparent substrates 2 and 3 are formed of a resin such as polyether sulfone, epoxy resin, or alkyl resin.

On both front and back surfaces of the substrates 2 and 3, laminated films 4a and 4b of SiNx and SiOx are formed.

Transparent strip electrodes 5 and 6 are formed on one surface of each of the substrates 2 and 3 on which the laminated film of SiNx and SiOx is formed.
Is formed, and then the alignment films 7 and 8 are formed.

The substrates 2 and 3 are opposed to each other so that the transparent electrodes 5 and 6 are orthogonal to each other, and the substrates 2 and 3 are bonded to each other by a sealing material 11 with a spacer 10 interposed therebetween. Next, the liquid crystal 12 is injected into the liquid crystal injection space 9 between the two substrates 2 and 3 to complete the liquid crystal display cell 1a. Polarizing plates 13 and 14 are arranged on the outer surfaces of the substrates 2 and 3 of the completed liquid crystal display cell 1a.

The laminated films 4a, 4 of SiNx and SiOx
b is densely formed on the surfaces of the substrates 2 and 3 by a sputtering method. The total film thickness of the stacked films 4a and 4b of SiNx and SiOx is 100 to 1000, preferably 200.
It is formed with a thickness of up to 600 °. Note that SiNx and SiO
The thickness ratio of x is preferably 1: 2.

If the film thickness is less than 100 °, the shielding property against gas and water is low, and if it exceeds 1000 °, cracks are generated in the laminated films 4a and 4b of SiNx and SiOx. The film formed on the substrate is a laminated film of SiNx and SiOx in order to improve the crack resistance of the transparent electrode.

SiOx as a gas barrier on a resin substrate
Oxygen plasma required when forming an inorganic single layer film and a transparent electrode (ITO) by a sputtering method tends to damage the resin substrate surface, so that the adhesion after film formation is poor,
Cracks are more likely to occur under high temperature and high humidity.

Therefore, in the present invention, the SiNx film can be formed without damaging the surface of the resin substrate by changing the oxygen plasma to the nitrogen plasma.
By sequentially laminating the iOx and the ITO film, the adhesion at the resin substrate interface can be improved. That is, it is possible to provide the liquid crystal display device 1 in which the crack resistance of the transparent electrode is improved.

[0018] and SiO _X monolayer film, although the comparative data of the crack resistance of the ITO film under high temperature and high humidity in the case of a laminated film of SiNx and SiOx shown in Table 1, the direction of the laminated film of SiNx and SiOx It can be seen that the crack resistance is significantly improved.

[0019]

[Table 1]

A dense SiNx / SiOx laminated film 4a, 4b having a thickness of 400.degree.
3, the gas (O ₂ ) barrier property is 0.1 CC / m ² · 24Hr · At under conditions of 40 ° C. and 90% RH.
m, the moisture permeability (H ₂ O) is 0.05 g / m ² · 24Hr, and the conventional one has a gas barrier property of about 0.5 cc / m ² ·
24Hr · Atm and moisture permeability of several g / m ² · 24Hr, it can be seen that gas and water shielding properties are improved.

Therefore, the display quality of the liquid crystal display device can be improved without gas or water entering the liquid crystal display cell 1a.

FIG. 2 is a sectional view of a liquid crystal display 21 showing another embodiment of the present invention. The same members as those in the first embodiment are denoted by the same symbols.

In the liquid crystal display device 21, not only both surfaces of the resin substrates 2 and 3 but also SiO ₂ , S
Resin films 15a and 15b made of a laminated film of iNx and SiOx or polyvinyl alcohol are formed. By doing so, the shielding properties of the substrates 2 and 3 are further improved.

In this embodiment, a simple matrix type liquid crystal display device has been described as an example. However, the present invention is not limited to this, and similar effects can be obtained with other liquid crystal display devices such as an active matrix type liquid crystal display device. Obtainable.

[0025]

According to the liquid crystal display device of the present invention, since a laminated film of SiNx and SiOx is formed on the surface of the resinous substrate, the shielding property against gas and water is improved, and gas and water are contained in the liquid crystal cell. Water does not enter, and the display quality of the liquid crystal display device is improved.

Further, it is possible to provide a highly reliable liquid crystal display device having improved crack resistance as compared with a conventional SiO ₂ single layer film.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a liquid crystal display device according to the present invention.

FIG. 2 is a sectional view showing another embodiment of the liquid crystal display device according to the present invention.

[Explanation of symbols]

 1,21 liquid crystal display device 2,3 substrate 4a, 4b laminated film of SiNx and SiOx

Claims (1)

(57) [Claims] 1. A liquid crystal display device between a pair of transparent substrate made of a resin formed by interposing a liquid crystal layer, a laminated film of SiN _X and SiO _X is formed on both surfaces of the pair of transparent substrates, the SiN _X is the adhesion at the transparent substrate interface
Between the transparent substrate and the SiO _X in order to improve the
A liquid crystal display device formed between the liquid crystal display devices.