JPH11133451A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make alignment surface flat and to stabilize the alignment state of liquid crystals by forming electrodes having a specific crystal grain size on substrates and forming alignment layers of a specific film thickness on these substrates. SOLUTION: The electrodes 2 having the crystal grain size below 0.1 μm are formed on the substrate 1 and the alignment layers 3 having the film thickness of 300 to 1000 angstrom are formed on the substrates 1 formed with the electrodes 2. For example, the transparent electrodes 2 are formed at 1000 angstrom by using an indium tin oxide(ITO) target by a sputtering method on the washed glass substrates 1. At this time, Ar is introduced as an introducing gas in such a manner that, for example, 1.5×10<-3> (Torr) may be attained. The transparent electrodes 2 of <=0.1 μm and average 0.05 μm in the crystal grain size formed in such a manner are formed to arbitrary patterns by a photolithography method and thereafter, polyimide films are formed as the alignment layers 3. Gap materials 5 and sealing materials 6 are formed after rubbing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a liquid crystal display device, and more particularly to a structure of a transparent electrode and an alignment film in a liquid crystal cell.

[0002]

2. Description of the Related Art Conventionally, in manufacturing a liquid crystal display device, only a film thickness of a transparent electrode is controlled by a vacuum deposition method, a sputtering method, a roll coating method, or a chemical vapor method, focusing on transmittance and resistance value. Had been. Further, the inorganic layer has also been designed by paying attention to the film thickness from the viewpoint of the passivation effect and the reflectance. The thickness of the alignment layer has been designed with attention paid to the reflectance of the substrate and the like.

As described above, in all of the transparent electrode, the inorganic layer, and the alignment layer, only the management based on the film thickness has been performed.

[0004]

However, in the above-mentioned prior art, since there is no limitation on the crystal grains of the electrode or the inorganic layer under the alignment layer, the amount of the chiral agent composed of the cholesteric liquid crystal using the nematic liquid crystal is not limited. Adjust 90 °
When twisted as described above, if the orientation film is thin and the crystal grain size is large, the surface state of the lower layer is affected, the tilt angle of the liquid crystal molecules becomes nonuniform, and there is a problem that poor alignment occurs. Also, as the size of the liquid crystal display device increases, it is necessary to reduce the resistance of the transparent electrode, and it is necessary to increase the thickness of the electrode portion.
When the electrode is thickened, poor alignment at the electrode edge and poor alignment due to non-uniform chiral due to the chromatographic effect during liquid crystal injection have occurred.

The present invention solves such a problem, and an object of the present invention is to form a smooth and flat alignment surface and stabilize the alignment.

[0006]

According to the present invention, there is provided a liquid crystal display device comprising a liquid crystal layer sandwiched between a pair of substrates having transparent electrodes formed on opposing inner surfaces, and an alignment film formed on the transparent electrodes. In the display device, the transparent electrode formed on the pair of substrates opposed to each other has a crystal grain size of 0.1 μm or less, and further has an inorganic crystal grain size of 0.1 μm or less between the transparent electrode and the alignment film. It is characterized in that a film is formed.

Further, the second liquid crystal display device of the present invention is characterized in that the alignment film is formed with a thickness of 300 Å to 1000 Å.

In a third liquid crystal display device according to the present invention, the inorganic film is made of TiO2-ZrO2, SiO2, TiO2, A
It is characterized by being made of any one of l2O3, CeO2 and Si3N4.

The thickness of the alignment layer is 100 to 1000
Angstroms is desirable, more preferably 300
~ 1000 angstroms. If it is less than 300 angstroms, the surface state of the lower transparent electrode is easily affected, and the tilt angle of the liquid crystal molecules becomes non-uniform. On the other hand, when the thickness exceeds 1000 angstroms, problems of resistance and alignment characteristics between the upper and lower transparent electrodes occur.

[0010] The crystal grain size of the transparent electrode and the inorganic film is desirably 0.1 µm or less. If it exceeds 0.1 µm, the irregularities on the surface become severe, and the tilt angle of liquid crystal molecules is likely to be affected.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

[Embodiment 1] FIG. 1 shows an embodiment of the present invention.
A transparent electrode 2 was formed on the cleaned glass substrate 1 by sputtering using an indium oxide-tin oxide (hereinafter, referred to as ITO) target at 1000 angstroms. At this time, 1.5 × 10 −3 Ar was introduced as an introduced gas.
(Torr) and O2 gas is introduced at 4 * 10 <-3>
It was introduced so as to be about 5 × 10 −3 (torr). In this way, the average grain size is 0.05 μm or less and the average is 0.05 μm.
m transparent electrodes 2 were formed. After the transparent electrode 2 was formed in an arbitrary pattern by a photo method, a polyimide film was formed as an alignment layer 3 in a thickness of 300 Å to 1000 Å, and after rubbing, a gap material 5 and a seal material 6 were formed to produce a liquid crystal display cell. .

Next, a conventional example will be described as a comparative example.

FIG. 2 is a view showing the structure of a conventional liquid crystal display device. A transparent electrode 2 'is formed on a glass substrate in the same manner as described above.
(ITO film) is formed.
It was introduced under the condition of 10-3 (torr). The thus formed ITO was patterned by a photo method, and an alignment layer 3 'also made of a polyimide film was formed to 250 Å, and then rubbed to produce a liquid crystal display cell in the same manner as described above. The crystal grain size of the transparent electrode 2 'of the liquid crystal display cell thus obtained was 0.5 to 2 [mu] m. Therefore, the surface state is very uneven. Then, a liquid crystal in which nematic liquid crystal is mixed with chiral is injected into the liquid crystal display cell and the above-described liquid crystal display cell. It was excellent and could obtain a stable orientation in a uniform twist state.

[Embodiment 2] This embodiment will be described with reference to FIG.

A transparent electrode 2 is formed to a thickness of 1000 angstroms by an electron beam (EB) evaporator using an ITO tablet. The conditions at this time are as follows: after vapor deposition at an introduced O2 pressure of 5.times.10@-5 to 8.times.10@-5 (torr), the alignment layer 3 made of polyimide is divided into several types in the range of 250 .ANG. After the formation, a liquid crystal display cell was manufactured in the same manner as in Example 1. At this time, the crystal grain size of the transparent electrode 2 was 0.05 μm or less.

Next, a comparative example will be described.

In the same manner as in the above, the EB vapor deposition machine is used to introduce O2
After depositing ITO at a pressure of 1.times.10@-5 to 5.times.10@-5 (torr), it is patterned into an arbitrary shape by a photo method to form a transparent electrode 2 ', and polyimide is formed on the transparent electrode 2'. A liquid crystal display cell was manufactured by forming an alignment layer having a thickness of 100 Å to 250 Å. At this time, the crystal grain size of the transparent electrode 2 'was measured to be 1 to 2 μm.
m.

Comparing these two results, the present embodiment is better than the first embodiment in that the crystal grain size of the transparent electrode is small. In particular, in the present embodiment, since the crystal grain size is 0.05 μm or less, good results can be obtained even when the thickness of the alignment layer is almost the same as 250 Å, and if the crystal grain size is further reduced, It seems that the orientation layer can be made thinner.

[Travel Example 3] In the same manner as in the embodiment of the present invention shown in Embodiment 1 or 2, ITO was prepared by using a crystal having a crystal grain size of 0.1 mm.
After being formed to a thickness of 1 μm or less, an inorganic film of TiO 2 and ZrO 2 is formed thereon by sputtering to form a film of 500 Å to 1000 Å, and an alignment layer 3 made of polyimide is further formed thereon to form a film of 400 Å to 1000 Å. I do. At this time, the size of the crystal grain size of the pre-distribution inorganic film was set to 0.1 μm or less. The alignment state of the liquid crystal display cell configured as described above was very stable and good.

In Examples 1 to 3 described above, the transparent electrode and the inorganic film were formed by a vacuum method. However, the crystal grains may be formed by other methods, for example, by applying a liquid composition such as a roll coating method or a spray method or by a chemical vapor method. A method may be adopted in which the conditions are set so that the diameter is 0.1 μm or less. Further, in addition to polyimide, polyimide amide, polyvinyl alcohol, polyamide and the like have the same effect as the alignment layer.
In the third embodiment, an inorganic film of TiO2-ZrO2 was used, but the present invention is not limited to this. For example, SiO2, Tr
iO2, Al2 O3, CeO2, Si3 N4 and the like.

[0021]

As described above, the transparent electrode has a crystal grain size of 0.1 μm or less, and an inorganic film having a crystal grain size of 0.1 μm or less is formed between the transparent electrode and the alignment film. Therefore, the orientation plane is almost smooth and almost flat. Accordingly, since the alignment surface is flat and stable, the alignment state of the liquid crystal is stabilized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a structure of a liquid crystal display device of the present invention.

FIG. 2 is a diagram showing a structure of a conventional liquid crystal display device.

[Explanation of symbols]

 1 ... substrate 2, 2 '... transparent electrode 3, 3' ... alignment layer, 4, 4 '... twist of liquid crystal 5 ... gap material 6 ... sealing material 7 ... Liquid crystal layer

[Procedure amendment]

[Submission date] September 30, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction contents]

[0006]

According to a method of driving a liquid crystal display device of the present invention, a method of manufacturing a liquid crystal display device in which a liquid crystal is sandwiched between a pair of substrates is performed by using an electrode having a crystal grain size of 0.1 μm or less. Forming on the substrate, 300 angstroms to 10 angstroms on the substrate on which the electrodes are formed.
Forming an alignment film having a thickness of 00 angstroms.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Deleted

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Deleted

Claims (3)

[Claims] 1. A liquid crystal display device in which a liquid crystal layer is sandwiched between a pair of substrates having transparent electrodes formed on opposing inner surfaces, and an alignment film is formed on the transparent electrodes. A transparent electrode having a crystal grain size of 0.1 μm or less, and an inorganic film having a crystal grain size of 0.1 μm or less formed between the transparent electrode and the alignment film. Display device. 2. The method according to claim 1, wherein said alignment film is 300 angstrom to 1 angstrom.
2. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is formed to have a thickness of 2,000 angstroms. 3. The inorganic film is made of TiO2-ZrO2, SiO
2. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is made of any one of 2, TiO2, Al2O3, CeO2, and Si3N4.