JP2001125084A - Liquid crystal element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the mutual effect of electric fields on pixels adjacent to each other. SOLUTION: An insulating member 4 having a thickness greater than that of an electrode 2b and a dielectric constant lower than that of a liquid crystal 3 is provided between the electrodes 2b and 2b adjacent to each other. The mutual effect of the electric fields on pixels adjacent to each other can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal device which performs light switching using a liquid crystal.

[0002]

2. Description of the Related Art Various types of liquid crystal panels (liquid crystal elements) for switching light using liquid crystals have been proposed. Hereinafter, this point will be described.

One type of liquid crystal panel is an active matrix type liquid crystal panel in which a thin film transistor (active element) such as a TFT is arranged in each pixel and has a nematic liquid crystal.

In such a liquid crystal panel, a twisted nematic mode is widely used at present, and details of the mode are described in “M. Schadt” and “W. Helfrich”. ) "Ap
Plied Physics Letters "1st
8, Vol. 4, No. 4 (issued February 15, 1971), pages 127 to 128 ".

[0005] Recently, an in-plane switching (In-P) using a lateral voltage has been disclosed.
There is a (lane switching) mode, and attention has been paid to improve the viewing angle characteristic which has been a drawback of the twisted nematic mode liquid crystal panel.

Further, a super twisted nematic (S
There is an upper Twisted Nematic mode.

Further, a rubbing process is performed in the same direction on both of the pair of substrates arranged with a predetermined gap therebetween, a nematic liquid crystal is sandwiched between the substrates to form a splay alignment, and the alignment state of the liquid crystal is determined by applying a voltage. The response speed was increased by changing the orientation to bend orientation by Bos et al. (Π cell) in 1983.

A liquid crystal panel in which the viewing angle characteristics are improved by performing phase compensation is disclosed by Uchida et al. In 1992 (OCB cell).

[0009]

In any of the above-mentioned liquid crystal panels, when the distance between pixels is reduced in accordance with high definition, the alignment state of the liquid crystal in the pixel becomes adjacent to the pixel. In the case of the above-described twisted nematic mode liquid crystal panel, a reverse tilt occurs, and the OLED is affected by the voltage applied to the pixel.
In the case of the CB cell, there is a problem in that light leakage occurs even when attempting to perform black display at a pixel in which the retardation distribution is disturbed, and the luminance decreases when attempting to perform white display.

[0010] The present inventors have investigated, the liquid crystal director near the end of the pixel, * electrical interaction with the equipotential surface distribution distorted by the pixel edge (reference symbol A ₁ in FIG. 2), and, * adjacent the intermolecular interactions, the two effects of the liquid crystal director that is oriented by the potential distribution (reference sign a ₂ in FIG. 2) between the electrode 2b and the electrode 2b to be in a direction different from the liquid crystal directors in the pixel central portion It was found that a disclination line was generated around the pixel.

As a method for solving such a problem,
There is a method of providing a black matrix as a light shielding portion between adjacent pixels, but when a black matrix is provided, the aperture ratio of the pixel is substantially reduced, and the light use efficiency is reduced. There was a problem.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid crystal element which prevents the influence of an electric field between adjacent pixels.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above circumstances, and has been made in consideration of the above circumstances, and has been described in connection with a pair of substrates arranged with a predetermined gap therebetween and a pair of substrates separated from each other along at least one substrate. In a liquid crystal element comprising: a plurality of electrodes arranged in a liquid crystal interposed between the pair of substrates; and an insulating member having a smaller dielectric constant than the liquid crystal, the electrode and the electrode being adjacent to each other. It is characterized in that it is arranged thicker than these electrodes.

[0014]

Embodiments of the present invention will be described below with reference to FIG.

As shown in FIG. 1, a liquid crystal element P according to the present invention comprises a pair of substrates 1 arranged with a predetermined gap therebetween.
a, 1b, a plurality of electrodes 2b, 2b arranged apart from each other along at least one substrate 1b, and a liquid crystal 3 sandwiched in a gap between the pair of substrates 1a, 1b.
It has. An insulating member 4 is arranged between the electrodes 2b adjacent to each other. The insulating member 4 is made of a material having a smaller dielectric constant than the liquid crystal 3 and has a higher dielectric constant than the electrode 2b. It is formed thick. Although FIG. 1 shows only two electrodes 2b and shows only one insulating member 4, the number of them is not limited to the illustrated one.

In this case, the alignment control films 5a, 5b are respectively provided on the pair of substrates 1a, 1b so as to be in contact with the liquid crystal 3.
It is preferable to dispose b and to perform a uniaxial alignment process such as a rubbing process on each of the alignment control films 5a and 5b.

The liquid crystal 3 is a nematic liquid crystal, and the direction of the uniaxial alignment processing of one of the alignment control films 5a or 5b and the direction of the uniaxial alignment processing of the other alignment control film 5b or 5a are mutually different. The directions may be the same.

The insulating member 4 is made of a photosensitive polyimide resin, a photosensitive polyamide, a cyclized rubber-based photoresist, a phenol novolak-based photoresist, an electron beam photoresist (polymethyl methacrylate, epoxidized-1,4- Polybutadiene).

Next, effects of the present embodiment will be described.

According to the present embodiment, the interaction with the liquid crystal director as described above is reduced by the insulating member 4, so that the influence of the electric field between adjacent pixels can be reduced.

In addition, there is no need to provide a black matrix, or the width of the black matrix can be reduced, so that a decrease in the aperture ratio of pixels and light use efficiency can be prevented.

[0022]

The present invention will be described below in more detail with reference to examples. Example 1 In this example, a liquid crystal panel (liquid crystal element) P shown in FIG. 1 was prepared.

The substrates 1a and 1b have a thickness of 1.1.
mm glass substrate was used.

Further, one glass substrate 1b has a width of 1 μm.
Two transparent electrodes 2b, 2b were arranged so as to be separated from each other with a gap of m, and one transparent electrode 2a was formed on the entire surface of the other glass substrate 1a. Each transparent electrode 2
For a and 2b, ITO (indium tin oxide) having a thickness of 1300 ° was used.

Further, a polyimide film having a thickness of 400 mm was formed as the orientation control films 5a and 5b so as to cover the transparent electrodes 2a and 2b. These alignment control films 5a and 5b are coated with SE-7992 manufactured by Nissan Chemical Industries, Ltd. by spin coating, pre-dried at a temperature of 80 ° C. for 5 minutes, and heated and baked at a temperature of 200 ° C. for 1 hour. Was formed.

Next, in one glass substrate 1b, 2
The insulating member 4 was formed in the gap between the two transparent electrodes 2b. The insulating member 4 is formed by applying * a 2 μm-thick PIQ manufactured by Hitachi Chemical Co., Ltd. by a spin coating method and * pre-drying at a temperature of 80 ° C for 5 minutes to form a polyimide film. A positive resist solution (S
AZ1350 manufactured by Chipley Co., Ltd. is applied, and * the surface of this resist solution, which covers the two transparent electrodes 2b, 2b, is irradiated with light through a resist mask (that is, the two transparent electrodes 2b, 2b). The portion corresponding to the gap of 2b is not irradiated with light), * Developed using a developing solution (MF312) containing tetramethylammonium hydroxide, * The polyimide film and resist solution in the portion irradiated with light Is removed, and the polyimide film remaining in the gap between the two transparent electrodes 2b is thermally cured.

The orientation control films 5a and 5b were subjected to a rubbing treatment (uniaxial orientation treatment). For this rubbing treatment, a nylon cloth (NF-
77, manufactured by Teijin Limited) using a rubbing roll, the roll pushing amount was 1.2 mm, and the feed rate was 10 c.
m / sec, the rotation speed was 1000 rpm, and the number of rubbing treatments was four.

Next, silica beads (average particle size: 6 μm) as spacers 6 are sprayed on one of the glass substrates 1a.
The pair of glass substrates 1a and 1b were bonded together such that both rubbing directions (directions of the uniaxial alignment treatment) were orthogonal to each other.

Thereafter, the pair of glass substrates 1a, 1
Liquid crystal (ZLI-4792) was injected into the gap between the substrates b.
Thus, a liquid crystal panel P having two pixels was formed by the two transparent electrodes 2b.

Thereafter, when a voltage of +5 V was applied to the transparent electrode 2a and a voltage of -5 V was applied to the other electrode 2b, and observed under crossed Nicols, the disclination line was 3 μm from the edge B of the pixel. It was found that it occurred at the position. (Comparative Example) In this comparative example, the above-described insulating member 4 was not formed, and the other configuration and the manufacturing method were the same as in Example 1 to produce a liquid crystal panel.

When the prepared liquid crystal panel was driven and observed in the same manner as in Example 1, it was found that a disclination line was generated at a position 6 μm from the edge B of the pixel. (Embodiment 2) In this embodiment, a liquid crystal panel having the same structure as that of Embodiment 1 was manufactured in the same manner as in Embodiment 1, but the alignment control films 5a and 5b formed so as to cover the transparent electrodes 2a and 2b were formed.
Is a polyimide film having a thickness of 400 ° C. * JALS2022 manufactured by JSR Co. is applied by a spin coat method, * pre-drying is performed at a temperature of 80 ° C for 5 minutes, and * at a temperature of 220 ° C. For 1 hour. Note that these alignment control films 5
The rubbing treatments a and 5b were performed two times under the same conditions as in Example 1.

The spacer 6 has an average particle diameter of 3 μm.
The rubbing directions are parallel to each other using silica beads of m.
Except for using No. 27, the glass substrates 1a and 1b were bonded by the same method as in Example 1. Note that, in the liquid crystal panel thus prepared, the liquid crystal 3 was in a splay alignment state.

Thereafter, the transparent electrodes 2a, 2a of the liquid crystal panel P
After applying a voltage of 10 V to the liquid crystal 3 to change the liquid crystal 3 from the splay alignment to the bend alignment, +5 is applied to one of the transparent electrodes 2a.
V and a voltage of -5 V to the other electrode 2b.
And observed under crossed Nicols, the disclination line was 0.5 μm from the edge B of the pixel.
It was found that it occurred at the position of m.

[0034]

As described above, according to the present invention,
Since the interaction with the liquid crystal director as described above is reduced by the insulating member, the influence of the electric field between adjacent pixels can be reduced.

In addition, it is not necessary to provide a black matrix, or the width of the black matrix can be reduced, so that a decrease in the aperture ratio of pixels and light use efficiency can be prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of the structure of a liquid crystal panel according to the present invention.

FIG. 2 is a diagram for explaining a conventional problem.

[Explanation of symbols]

 1a, 1b Glass substrate (substrate) 2a, 2b Transparent electrode (electrode) 3 Liquid crystal 4 Insulating member 5a, 5b Alignment control film P Liquid crystal panel (liquid crystal element)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hirohide Munakata 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Satoshi Miura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon F term in the company (reference) 2H090 HA05 HA08 HB08X HB08Y HC10 HD14 JA03 JC03 KA04 LA01 LA04 MA07 MB01 MB14

Claims (3)

[Claims] 1. A pair of substrates disposed with a predetermined gap therebetween, a plurality of electrodes disposed apart from each other along at least one substrate, and sandwiched between the pair of substrates. A liquid crystal element comprising: a liquid crystal; and an insulating member having a dielectric constant smaller than that of the liquid crystal, wherein the insulating member is disposed between adjacent electrodes so as to be thicker than these electrodes. 2. The alignment control film according to claim 1, wherein an alignment control film is disposed on each of the pair of substrates so as to be in contact with the liquid crystal, and each of the alignment control films is subjected to a uniaxial alignment process. Liquid crystal element. 3. The method according to claim 1, wherein the liquid crystal is a nematic liquid crystal, and a direction of the uniaxial alignment processing of one of the alignment control films is the same as a direction of the uniaxial alignment processing of the other alignment control film. The liquid crystal device according to claim 2, wherein: