Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
1998-03-31
2001-01-09
Sikes, William L. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S123000, C349S133000, C349S172000, C349S174000
Reexamination Certificate
active
06172727
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal cell using an antiferroelectric liquid crystal. Particularly, it relates to a liquid crystal cell having an electrode substrate with color filters.
2. Description of the Related Art
Recently, in a liquid crystal device, a liquid crystal cell has been widely used due to advantages of thin configuration, of light weight, and of low power consumption. In general, almost all liquid crystal cells are formed of TN (twisted nematic)-type liquid crystal cells which use nematic liquid crystals.
In this case, since the driving of the TN-type liquid cell depends on an anisotropic characteristic of a dielectric constant of the liquid crystal cell, the response speed (time) is very slow, and it is required to improve the response speed in the TN-type liquid cell.
On the other hand, another liquid crystal cell, which uses the liquid crystal cell having a chiral smectic C phase (below, SmC* phase) indicating a ferroelectric characteristic (this type of liquid crystal was found by Mr. Meyer et al.), has a high response speed and a good storage characteristic which could not be achieved by the above TN-type liquid cell. Accordingly, recently, research and development have been preformed to realize a ferroelectric liquid crystal cell having the above good characteristic.
However, when realizing both a good molecular alignment and a good storage characteristic, both of which are required of the ferroelectric liquid crystal, in an actual liquid crystal cell, many problems remain because the ferroelectric liquid crystal is easily damaged by a shock applied from the outside.
Furthermore, recently, an antiferroelectric phase (SmC
A
* phase) which has three stable states at a low temperature of the SmC
A
* phase was found by Chandani et al. Since this SmC
A
* phase has a thermodynamically stable state in which dipoles (i.e., liquid crystal molecules) are arranged in anti-parallel for each adjacent liquid crystal layer, the SmC
A
* phase has a function which produces an electric field-induced phase transfer between the antiferroelectric phase and the ferroelectric phase, which features have apparent threshold values and a double hysteresis characteristic for plus and minus supply voltages.
Accordingly, research and development have begun on the antiferroelectric liquid crystal cell, as a new display method utilizing this switching operation. The present invention aims to provide an improved liquid crystal cell using an antiferroelectric liquid crystal, and particularly, a liquid crystal cell having an electrode substrate with color filters.
SUMMARY OF THE INVENTION
The object of the present invention is to provide an improved liquid crystal cell using an antiferroelectric liquid crystal.
Another object of the present invention is to provide an improved liquid crystal cell having an electrode substrate with color filters in one side of the electrode substrate.
In accordance with a first aspect of the present invention, there is provided a liquid crystal cell including: an electrode substrate with color filters; an opposite electrode substrate; a first alignment film provided on the electrode substrate with color filters; a second alignment film provided on the opposite electrode substrate; an antiferroelectric liquid crystal provided between the first and second alignment films; and the electrode substrate with color filters and the opposite electrode substrate being superimposed so as to face each other through the first alignment film, the antiferroelectric liquid crystal, and the second alignment film; wherein an alignment process of the first alignment film is performed based on a rubbing density larger than the rubbing density of the second alignment film so that an angle of layer rotation of the antiferroelectric liquid crystal is defined within a predetermined allowable angle range.
In accordance with a second aspect of the present invention, there is provided a liquid crystal cell including: an electrode substrate with color filters; an opposite electrode substrate; a first alignment film provided on the electrode substrate with color filters; a second alignment film provided on the opposite electrode substrate; an antiferroelectric liquid crystal provided between the first and second alignment films; a plurality of walls each having line-shaped configuration provided on the first alignment film; and the electrode substrate with color filters and the opposite electrode substrate being superimposed so as to face each other through the first alignment film, the antiferroelectric liquid crystal, the plurality of walls each having line-shaped configuration, and the second alignment film; wherein an alignment process of the first alignment film is performed based on rubbing density larger than the rubbing density of the second alignment film so that an angle of layer rotation of the antiferroelectric liquid crystal is defined within a predetermined allowable angle range.
In accordance with a third aspect of the present invention, there is provided a liquid crystal cell including: an electrode substrate with color filters; an opposite electrode substrate; a first alignment film provided on the electrode substrate with color filters; a second alignment film provided on the opposite electrode substrate; an antiferroelectric liquid crystal provided between the first and second alignment films; and the electrode substrate with color filters and the opposite electrode substrate being superimposed so as to face each other through the first alignment film, the antiferroelectric liquid crystal, and the second alignment film; wherein an alignment process of the first alignment film is performed based on rubbing density larger than the rubbing density of the second alignment film so that the difference between phase difference values of each refractive index after the alignment process of each alignment film is defined within a predetermined allowable range.
In accordance with a fourth aspect of the present invention, there is provided a liquid crystal cell including: an electrode substrate with color filters; an opposite electrode substrate; a first alignment film provided on the electrode substrate with color filters; a second alignment film provided on the opposite electrode substrate; an antiferroelectric liquid crystal provided between the first and second alignment films; a plurality of walls each having line-shaped configuration provided on the first alignment film; and the electrode substrate with color filters and the opposite electrode substrate being superimposed so as to face each other through the first alignment film, the antiferroelectric liquid crystal, the plurality of walls each having line-shaped configuration, and the second alignment film; wherein an alignment process of the first alignment film is performed based on rubbing density larger than the rubbing density of the second alignment film so that the difference between phase difference values of each refractive index after the alignment process of each alignment film is defined within a predetermined allowable range.
In accordance with a fifth aspect of the present invention, there is provided a liquid crystal cell including: an electrode substrate with color filters; an opposite electrode substrate; a first alignment film provided on the electrode substrate with color filters; a second alignment film provided on the opposite electrode substrate; an antiferroelectric liquid crystal provided between the first and second alignment films; and the electrode substrate with color filters and the opposite electrode substrate being superimposed so as to face each other through the first alignment film, the antiferroelectric liquid crystal, and the second alignment film; wherein an alignment process of the first alignment film is performed based on a rubbing density larger than the rubbing density of the second alignment film so that an angle of layer rotation of the antiferroelectric liquid crystal is defined within a predetermined allowabl
Fujikawa Takayuki
Ozaki Masaaki
Sano Tetsuya
Yamamoto Norio
Chowdhury Taifur R.
Denso Corporation
Pillsbury Madison & Sutro LLP
Sikes William L.
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