JPH0990332A - Liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liquid crystal display element having a good display grade and high reliability without impairing the productivity at the time of forming a liquid crystal cell by providing the outside surfaces of first and second electrode substrates with planar external supporting bodies for first and second substrates which are mounted at the outside surfaces of these substrates and have irreversible expandability. SOLUTION: First and second transparent substrates 16, 17 consisting of ITO are respectively patterned and formed on first and second glass substrates 13, 14 constituting the first and second electrode substrates 11, 12 which are the liquid crystal display element 10. Further, first and second oriented films 18, 19 are formed on the respective transparent electrodes 16, 17. The two electrode substrates 11, 12 are fixed onto the flat plates by the external supporting bodies 23, 24 for the first and second substrates which bodies are formed on the outer side of the first and second electrode substrates 11, 12 constituting the liquid crystal cell, consist of expanded films of polysilane having a volumetric expansion rate of 20% and are not distorted by immersion into pure water, by which the spacing between the two electrode substrates 11, 12 is maintained nearly uniform without interposing spacers between the electrode substrates.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a liquid crystal display device that uniformly maintains a gap between opposed electrode substrates.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have been used as display devices ranging from small devices such as wristwatches to large devices such as personal OA equipment such as word processors and desktop personal computers because they have the advantages of thinness, light weight and low power consumption. A liquid crystal display device using is widely used.

In a liquid crystal display element constituting such a liquid crystal display device, generally, a pair of electrode substrates each having a transparent electrode are opposed to each other with a spacer interposed therebetween, and the periphery thereof is adhered with a sealing material to form a liquid crystal cell. The liquid crystal composition is formed and the liquid crystal composition is sealed in the gaps of the liquid crystal cell. That is, a spacer is mixed in the liquid crystal composition between both electrode substrates.

As a conventional spacer, a spacer made of resin or glass-based material or spherical fine particles which are dispersed on an electrode substrate by applying a coating treatment of a coloring agent or an adhesive to these, or Japanese Patent Laid-Open No. 11256/1993. As disclosed in JP-A-5-272223 and the like, an inorganic or organic compound formed to have a film thickness equal to the gap thickness on the electrode substrate surface is left only in the non-pixel portion by using a photolithography technique. The formed spacer, and further, JP-A-5-173.
As disclosed in Japanese Patent Application Laid-Open No. 147 and Japanese Patent Application Laid-Open No. 6-67135, a spacer pattern is previously formed on a screen or a sheet-shaped organic compound by a printing method, and the spacer pattern is transferred to a non-pixel portion of an electrode substrate. A spacer or the like formed by the above is used.

[0005]

Conventionally, in a liquid crystal cell of a liquid crystal display device, in order to maintain a uniform gap over the entire surface between both electrode substrates, spacers made of spherical fine particles dispersed between both electrode substrates or A spacer formed only on the non-pixel portion on the electrode substrate by the photolithography technique, and a spacer formed by pattern printing only on the non-pixel portion on the electrode substrate are interposed.

However, when the spacers are interposed between both electrode substrates in this way, the spacers of the spherical fine particles are arranged on the electrode substrates by spraying, so that the spacers can be uniformly arranged. Although it is easy and productivity can be improved, it is difficult to selectively place it at an arbitrary position on the electrode substrate, and the spacers are also scattered in the pixel area. There is a problem in that the light control action of the composition and the orientation direction are disturbed, and the display quality is degraded, such as a reduction in contrast.

Further, the spacer formed on the non-pixel portion of the electrode substrate by the photolithography technique or the printing method can be easily regulated so that the arrangement is limited to the non-pixel portion, but it is more difficult than the spherical fine particles. , The forming process is complicated and the productivity is remarkably reduced, and in the printing method, when a deviation occurs at the time of printing, the spacer pattern enters the pixel region on the electrode substrate and is printed, It has a problem that the display quality may be deteriorated.

Further, when the spacers are formed by the photolithography technique or the printing method, if these spacers are formed before the rubbing treatment of the alignment film and the rubbing treatment is performed after the spacer formation, the spacers are also rubbed together.
There is a risk of causing streak unevenness centered on the spacer, and while such alignment defects reduce the display quality, when the spacer is formed after the rubbing process, the rubbing process state changes during the spacer forming process, There is also a problem that the display quality is deteriorated due to the poor orientation of the arrow.

Therefore, the present invention eliminates the above-mentioned problems, and in a liquid crystal cell in which a gap between opposed electrode substrates is uniformly maintained over the entire surface, productivity is not impaired when the liquid crystal cell is formed, and a display defect occurs. It is an object of the present invention to provide a highly reliable liquid crystal display device capable of preventing the above-mentioned problem and obtaining good display quality.

[0010]

As a first means for solving the above problems, the present invention has a first electrode substrate having a first transparent electrode and a second electrode having the second transparent electrode. A second electrode substrate facing the electrode substrate with a gap, a sealing means surrounding the gap, a liquid crystal composition held in the gap surrounded by the sealing means, and the first electrode. A first planar outer support attached to the outer surface of the substrate and having an irreversible expansion property, and a second planar substrate attached to the outer surface of the second electrode substrate and having an irreversible expansion property And an outer support.

The present invention also provides a second object for solving the above problems.
As the means, the first outer substrate support and the second outer substrate support in the first means are composed of a composition that is hydrolyzed to expand and cure.

According to the present invention, by the above means, a spacer is not interposed in the gap between the opposite electrode substrates,
Since the gap can be maintained uniformly over the entire surface, a complicated spacer formation process is not required, and the productivity is improved, and the spacer is interposed in the liquid crystal composition, which lowers the contrast and causes poor alignment. It is possible to prevent, obtain a good display image, and improve reliability.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIG.
This will be described with reference to FIG. Reference numeral 10 denotes a liquid crystal display element, which is a first liquid crystal display element that forms the first and second electrode substrates 11 and 12.
And Ind on the second glass substrates 13 and 14, respectively.
first and second transparent electrodes 16 and 17 made of ium tin oxide (hereinafter abbreviated as ITO) are patterned, and AL is formed on each transparent electrode 16 and 17.
First and second alignment films 18 and 20 made of -1051 (trade name of Japan Synthetic Rubber Co., Ltd.) are formed.

Then, in the gap between the two electrode substrates 11 and 12 sealed with a seal adhesive 21 which is a sealing means made of ES-5500 (trade name of Mitsui Toatsu Co., Ltd.) mixed with a glass fiber having a diameter of 5 μm, ZLI- 1132 (trade name of E. Merck Co., Ltd.) is held as the liquid crystal composition 22.

And the first and second glass substrates 13,
On the outer side of 14, there are formed first and second outside-substrate supports 23, 24 which are formed of a swelling film of polysilane described later and have a volume expansion coefficient of about 20%.

Numerals 26 and 27 are first and second polarizing plates.

Next, the manufacturing process of the liquid crystal display element 10 will be described.

First, after forming the first and second transparent electrodes 16 and 17 on both glass substrates 13 and 14, both glass substrates 13 and 14 are washed with a neutral detergent and pure water to form the first and second transparent electrodes. After the second alignment films 18 and 20 are applied by offset printing, they are temporarily dried at 80 ° C. for 60 seconds on a hot plate, and heat-treated at 180 ° C. for 30 minutes in a hot air oven.

Then, both glass substrates 13 and 14 are heated from the hot air oven.
Was taken out, air-cooled for 10 minutes, and then rubbed in a certain direction with a nylon cloth for orientation treatment, and a transfer (XA-208 (manufactured by Fujikura Kasei Co., Ltd.)) (not shown) prepared by further mixing fine silver particles. It is applied to form the first and second electrode substrates 11 and 12.

After this, one of, for example, the first electrode substrate 1
1 is printed with a seal adhesive 21 to form a liquid crystal composition 22.
The first and second electrode substrates 11 and 12 are arranged to face each other so that the liquid crystal molecules therein are twisted by 90 °, and heated while applying pressure to cure the seal adhesive 21 to form a liquid crystal cell.

Next, a 0.5% by weight solution of butyl polysilane in cyclohexanone is applied by offset printing to the outside of the first and second electrode substrates 11 and 12 of this liquid crystal cell, and 100 is applied on a hot plate. The mixture is heated to ° C, the solvent is dried and removed, and polysilane thin films 23a and 24a are formed as shown in Fig. 2A. When pure water is offset-coated on the polysilane thin films 23a and 24a and immersed for 20 minutes, the polysilane thin films 23a and 24a are hydrolyzed and expanded in the directions indicated by arrows a to d, as shown in FIG. Is cured in the flat plate state. Thereafter, the liquid crystal cell is heated to 120 ° C. on a hot plate to evaporate the pure water and form the first and second outside substrate supports 23 and 24 made of a swelling film of polysilane having a volume expansion coefficient of 20%. To do.

In this way, the liquid crystal cell in which the substrate outside supports 23 and 24 are formed outside the both electrode substrates 11 and 12 is placed in a vacuum chamber, the inside of the liquid crystal cell is depressurized, and then the pressure difference between the inside and outside of the liquid crystal cell is set. 2C is used to inject the liquid crystal composition 22 into the gap between the electrode substrates 11 and 12 of the liquid crystal cell, as shown in FIG.
The liquid crystal display element 10 is obtained by sealing the inlet and further attaching the polarizing plates 26 and 27.

When the thickness of the gap in the liquid crystal cell of the liquid crystal display element 10 thus obtained was measured, it was found to be approximately 5 to 5.1 μm at 5 points, indicating that the thickness was substantially uniform. When an image was displayed on the liquid crystal display element 10, the black level transmittance was low and the contrast ratio was improved by about 20% as compared with a conventional device in which spherical fine particles were dispersed as spacers. In addition, no defective orientation was observed.

According to this structure, a swelling film of polysilane having a volume expansion coefficient of 20% formed on the outside of the first and second electrode substrates 11 and 12 constituting the liquid crystal cell is immersed in pure water. The two electrode substrates 1 and 2 are supported by the first and second outside substrate supports 23 and 24 which are expanded and hardened by
By fixing and supporting 1 and 12 in a plate shape, both electrode substrates 11 and 12 can be formed without interposing a spacer between the electrode substrates.
It is possible to maintain a substantially uniform gap, and it is possible to improve the display quality without causing the disturbance of the light control action in the pixel region and the disturbance of the alignment direction which have been conventionally caused by the spacer.

Moreover, the process of forming the support 23, 24 outside the substrate is easy, and the support 23, 24 outside the substrate can be manufactured in about 1 minute including the formation of the polysilane thin film and the immersion of pure water. The productivity can be improved as compared with the conventional liquid crystal display element in which the spacer is formed in the non-pixel portion by the graphic technique or the printing method.

Next, a comparative example will be described.

(Comparative Example 1) In this comparative example, in order to keep the gap between the two electrode substrates 11 and 12 constant without using the outside-substrate supports 23 and 24 in the embodiment of the invention described above. In the embodiment of the present invention, micro pearls having a diameter of 5 μm (trade name of Sekisui Fine Chemical Co., Ltd.), which are spacers, are sprayed at a spraying density of 110 particles / mm ² between the two electrode substrates 11 and 12. Is similar to.

When the liquid crystal display device thus obtained is driven to display an image, spacers are also scattered in the pixel region, so that the spacers cause light leakage and shine white and black. The level transmittance was not lowered, and the contrast ratio was lowered as compared with the embodiment. Further, in some liquid crystal display elements, alignment defects, which are considered to be caused by uneven dispersion of spacers, are locally observed and display quality is degraded.

(Comparative Example 2) In this comparative example, in order to maintain a constant gap between the electrode substrates 11 and 12 without using the support members 23 and 24 outside the substrate in the embodiment of the invention described above. After the alignment films 18 and 20 are formed, both electrode substrates 11 and 1 are formed.
A spacer is formed in the non-pixel portion between the two by a photolithography technique, and the rest is the same as the embodiment of the invention.

That is, in this comparative example, a resist material having a film thickness of 5 μm is printed and applied on the alignment film of one of the electrode substrates and then patterned by photolithography to form a columnar shape having a cross section of 10 × 10 μm in the non-pixel portion. Form spacers.
Then, the alignment film is rubbed to assemble a liquid crystal cell.

When a liquid crystal display device obtained by injecting a liquid crystal composition into such a liquid crystal cell was driven to display an image, there was no spacer in the pixel region. (Comparative Example 1)
As described above, there is no occurrence of light leakage due to the spacer, and although the same contrast as that of the embodiment is obtained, deterioration of the alignment film due to the photolithography process is locally observed, and alignment failure occurs, or There were several spots of rubbing streaks centered on the spacer, and the display quality was degraded.

The present invention is not limited to the embodiments of the invention described above, and modifications can be made without departing from the spirit of the invention. For example, the support outside the substrate can be expanded or contracted by temperature and humidity or outside light. As long as it does not exist, its material is arbitrary, but it is more preferable that the volume change after expansion and hardening is small. Further, the structure of the liquid crystal display element is arbitrary such as having a filter or a black matrix, and may be an active matrix driving type.

[0033]

As described above, according to the present invention, both electrode substrates can be easily formed, and can be formed on the outside of the first and second electrode substrates in a short time and expansion-cured. The support outside the substrate, which is held in a flat plate shape, can hold the gap between both electrode substrates evenly, and display due to the deterioration of contrast and the disorder of the alignment characteristics, which was conventionally caused by providing a spacer between both electrode substrates. It is possible to obtain a liquid crystal display device having a good display image, which can prevent the deterioration of quality and does not decrease the productivity.

[Brief description of drawings]

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

2A and 2B show a process of forming a support outside a substrate according to an embodiment of the present invention, FIG. 2A is a schematic cross-sectional view showing a polysilane thin film formation, and FIG. 2B is a schematic cross-sectional view showing a polysilane thin film after expansion curing. (C) is a schematic cross-sectional view showing the time of injecting a liquid crystal composition into a liquid crystal cell.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Liquid crystal display element 11 ... 1st electrode substrate 12 ... 2nd electrode substrate 16 ... 1st transparent electrode 17 ... 2nd transparent electrode 18 ... 1st alignment film 20 ... 2nd alignment film 22 ... Liquid crystal Composition 23 ... First support outside substrate 24 ... Second support outside substrate

Claims (2)

[Claims] 1. A first electrode substrate having a first transparent electrode, a second electrode substrate having a second transparent electrode facing the first electrode substrate with a gap, and the gap. A sealing means surrounding the first electrode substrate, a liquid crystal composition held in the gap surrounded by the sealing means, and a flat first substrate attached to the outer surface of the first electrode substrate and having an irreversible expansion property. A liquid crystal display device comprising: an outer support; and a planar second outer support attached to the outer surface of the second electrode substrate and having an irreversible expansion property. 2. The liquid crystal display element according to claim 1, wherein the first support outside the substrate and the second support outside the substrate are composed of a composition that is hydrolyzed and expands and hardens.