JPH0381728A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To obtain orientation treating layers which can be uniformly and easily formed by providing flattening layers of prescribed materials and the orientation treating layers for LB films on electrodes. CONSTITUTION:TFT elements and the driving electrodes 2 are formed by sputtering of ITO on a glass substrate 1. The surface thereof is then spin coated with 0.3% chloroform soln. of polyisopropyl fumarate (PF) to form the flattening layer 3. 0.1% chloroform soln. of the PF is developed on a water surface and is compressed to form the L (Langmuir) film. The substrate 1 is immersed in the liquid and is pulled up to accumulate two layers of the LB films. These films are dried by heating to obtain the PF orientation treating layer 4. After a counter electrode 9 is formed on another glass substrate 10, 1% chloroform soln. of the PF is applied thereon to form the flattening layer 8. The LB film is formed thereon and is dried by heating to obtain the PF orientation treating layer 7. Two sheets of the glass plates are adhered apart a prescribed spacing by sealant 6 and TN liquid crystal 5 is sealed therebetween.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal display element that does not use alignment treatment by rubbing.

[Conventional technology 1] The conventional method for producing an alignment layer is to coat a polymer such as polyimide on the surface of a substrate with electrodes attached.

It is common to use a method called the rubbing method, which involves rubbing with cloth, leather, etc. for orientation treatment. Further, there are methods using a silane coupling agent or the like as an alignment treatment agent, methods using vapor deposition of silicon oxide, etc., but these are not very common for reasons such as cost, productivity, and stability.

In addition, for example, polyamic acid can be mixed with Langmuir-
There is a report that twisted nematic (hereinafter abbreviated as TN) mode liquid crystals are arranged by an alignment layer formed by the Blodgett (hereinafter abbreviated as LB) method and processed to form a polyimide.

[Problems to be Solved by the Invention] Currently, the polymer film formation/rubbing method carried out by boat involves surface treatment by direct contact, which not only generates a large amount of dust but also causes static electricity to be charged on the surface, resulting in thin film transistors and two terminals. There is a problem in that it destroys the element and further destroys the electrode. In addition, the alignment treatment layer applied by the LB method requires the accumulation of several to several tens of layers, but the process is precise and time-consuming, and increasing the number of accumulated layers may result in areas where the alignment becomes disordered. .

There were issues such as difficulty in finding suitable conditions.

In order to solve these problems, the present invention aims to provide a liquid crystal display element having an alignment layer that is uniform and easily formed without using alignment treatment by rubbing.

[Means for Solving the Problems] The liquid crystal display element of the present invention is a liquid crystal display element in which a liquid crystal is sandwiched between two opposing 1i electrode substrates.

At least 61 of the electrode substrates are characterized in that they have a flattening layer made of polydialkyl fumarate and an LB film alignment layer made of polydialkyl fumarate on 'WtI. .

[Function] ITO (Indiu
m Tin Oxide) transparent electrode is used.

The surface of ITOIli is rough, with surface steps of about 100 mm for vapor-deposited films and 620 to 30 mm for sputtered films1.
The thickness of a monomolecular film deposited by the normal LB method is several angstroms, and the first several tens of layers that are accumulated are used only to fill in the surface steps. The situation is exactly the same when there is an insulating film such as silicon oxide on top of ITO.

After forming a flattening layer on the 1fli, if an alignment treatment layer is formed using the LB film, the liquid crystal will be aligned uniformly in one layer or at most several layers. Polydialkyl fumarate can be formed into a homogeneous film with a thickness of several hundred angstroms using a spin code, making it ideal as a material for the flattening layer. It is known that it is possible to easily form a defect-free homogeneous film (Denki et al. Bimetallic Surface Technology, 39 (9), 497 (1988)).
Since it does not contain ions, it is most suitable as an alignment treatment layer.

[Examples] Example 1 FIG. 1 is a sectional view schematically showing the structure of a liquid crystal display element in Example 1. A TPT (thin film transistor) element and a driving T4 pole 2 were formed on a glass substrate 1 by ITO sputtering. Using a spin coater on top of that,
A 0.3% chloroform solution of polydiisopropyl fumarate was applied at a rotation speed of 200 Or, p, m to form a polydiisopropyl fumarate flattening layer 3 having a thickness of 100 angstroms. There were no defects in the planarization layer, the fine step difference of several tens of angstroms was alleviated, and the influence of ITO grain boundaries could be eliminated.

Next, add 0.0% polydiisopropyl fumarate. By spreading it on the water surface with a 1% chloroform solution and compressing it,
The zero surface pressure of the L (Langmuir) film was 25 mN.
/ m at a speed of 6 mm/min.
was immersed and then pulled up at the same speed to accumulate two layers of LB film. By heating and drying at 80° C. for 1 hour, a polydiisopropyl fumarate alignment treatment layer 4 was obtained.

In addition, after forming the opposite pole 9 on another glass substrate 1O by ITO vapor deposition, a 1% chloroform solution of bodge isopropyl fumarate was applied at 3000 r, p using a spin coater.
, m, to form a polydiisopropyl fumarate flattening layer 8 with a thickness of 400 angstroms.
6 mm/m while keeping the surface pressure at 25 mN/m.
Pull up in the direction perpendicular to the substrate l at a speed of min, and LB
A monolayer was formed. By heating and drying at 80°C for 1 hour, the polydiisopropyl fumarate alignment treatment layer 7
I got it.

The two glass substrates thus prepared were adhered with a sealant 6 at a distance of 7 gm, and a TN liquid crystal 5 was sealed therein. The liquid crystal is aligned uniformly within the 5-inch diagonal LCD panel.
The display quality was not different from that of a liquid crystal display element having an alignment film made by rotationally rubbing polyimide with a nylon cloth.

Example 2 A polydiisopropyl flattening layer was formed on the drive electrode in the same manner as in Example 1.Next, polyditert-butyl fumarate was spread on the water surface with a 0.1% tetrahydrofuran solution and compressed. While keeping the zero surface pressure of the L film at 20 mN/m,
Dipping and pulling were repeated at a speed of n to accumulate four layers of LB film. By heating and drying at 80° C. for 1 hour, a polydi-tertiary-butyl fumarate alignment layer was obtained.

On the other hand, a silicon oxide insulating layer was formed on the counter electrode by sputtering, and a polyimide film was formed by screen printing and baking, and rotational rubbing was carried out at a rubbing density of 30 using a 2 mm 0-pile nylon cloth.

A polyimide orientation treatment layer was used.

When a liquid crystal display element was assembled and evaluated in the same manner as in Example 1, the liquid crystal was uniformly aligned and the display quality was good.

Example 3 MIM (metal insulator) on a glass substrate
The metal element and drive electrode were formed by ITO sputtering. On top of that, use a spin coater to coat the film to a thickness of 200.
An Angstrom polydicyclohexyl fumarate planarization layer was formed. There were no fine steps of several tens of angstroms on the surface of the flattened layer, and the influence of ITO grain boundaries could be eliminated.

Next, polydicyclohexyl fumarate.

A 0.1% ethyl acetate solution was spread on the water surface and compressed to form an L film. While maintaining the surface pressure at 25 mN/m, the material was pulled up at a speed of 4 mm/min and heated to 100°C.
By heating and drying, a polydicyclohexyl fumarate alignment layer was formed.

Further, after forming a counter electrode on another glass substrate by ITO sputtering, a flattening layer of polydicyclohexyl fumarate and an alignment treatment layer were formed in the above steps. The substrates were pulled up in directions perpendicular to each other.

Two electrode substrates were adhered with a sealant at an interval of 8 μm, and TN liquid crystal was encapsulated. The liquid crystal was aligned uniformly within the 5-inch diagonal liquid crystal panel, and the display quality was no different from that of a liquid crystal display element with an alignment film made by rotationally rubbing BoJimide with a nylon cloth. As described above, the present invention is characterized by the excellent film-forming properties of polydialkyl fumarate, and is not limited in any way to the type of alkyl group or degree of polymerization. In addition, the structure of the liquid crystal display element may include a color filter and an insulating layer, and may be a simple matrix drive method or an ST
Similar effects can be obtained with N (super twisted nematic) liquid crystal and Sm (smectic) liquid crystal.

(Effects of the Invention) As described above, according to the present invention, in a liquid crystal display element in which a liquid crystal is sandwiched between two opposing electrode substrates, at least one of the electrode substrates has a polydialkyl fume material on the electrode. By having a flattening layer made of carbonate and an LB film alignment layer made of polydialkyl fumarate, it has an alignment layer that is uniform and easily formed without using alignment treatment by rubbing. We were able to provide a liquid crystal display element with the following characteristics.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view schematically showing the structure of a liquid crystal display element in Example 1 of the present invention. l...Glass substrate 2...Electrode 3...Polydialkyl fumarate flattening layer 4...Polydialkyl fumarate LB film alignment treatment layer 5...Liquid crystal 6...Sealing agent 7... Polydialkyl fumarate L B lli alignment treatment layer 8...Polydialkyl fumarate flattening layer 9...Electrode lO...Glass substrate or higher

Claims (1)

[Claims] In a liquid crystal display element in which a liquid crystal is sandwiched between two opposing electrode substrates, at least one of the electrode substrates has a flattening layer made of polydialkyl fumarate on the electrode, and a flattening layer made of polydialkyl fumarate on the electrode. Langm to be
A liquid crystal display element comprising a uir-Blodgett film alignment treatment layer.