Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2000-02-07
2002-07-02
Sikes, William L. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S153000, C349S106000
Reexamination Certificate
active
06414733
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a color liquid crystal display and, particularly, to a color liquid crystal display which has high display qualities and is highly reliable.
In recent years, color liquid crystal displays have attracted remarkable attention as flat displays. One example of these color liquid crystal displays has a schematic structure comprising a color filter substrate including a black matrix, a colored layer consisting of plural colors (three primary colors: red (R), green (G) and blue (B)), a transparent electrode and an oriented layer, a counter electrode substrate including a thin film transistor (TFT element), a pixel electrode and an oriented layer, and a liquid crystal layer formed by opposing these both substrates to each other with a predetermined gap between them, sealing by a sealing member and filling a liquid crystal material in the gap.
In such a color liquid crystal display, the aforementioned gap is just the thickness of the liquid crystal. The thickness of the above liquid crystal layer, namely the distance between the color filter substrate and the counter electrode substrate must be kept strictly constant to enable exhibition of high display efficiencies which is required to a color liquid crystal display, including high speed responsibility, high contrast ration and wide angle of view. This is the reason why the following settings are taken. Specifically, before the color filter substrate and the counter electrode substrate are applied to each other, glass beads or plastic beads with a predetermined diameter and uniform grain diameter are dispersed as a spacer in either one of the color filter substrate and the counter electrode substrate. Thereafter, both substrates are applied to each other and sealed by a sealing member. Thus, the distance of the gap between both substrates, namely the thickness of the liquid crystal layer is set corresponding to the diameter of the glass beads or plastic beads.
However, because a curable synthetic resin is usually used as the sealing member, the generation of reaction gas and the elution of a solvent are caused in a curing process after the color filter substrate and the counter electrode substrate are applied to each other and sealed. There is the case where the liquid crystal layer is thereby contaminated and hence produces display nonuniformity, leading to reduced display qualities.
In order to solve such a problem, a color liquid crystal display is proposed in which an organic film is formed inside of the sealing member to prevent the liquid crystal layer from being contaminated with the reaction gas and eluents from the sealing member (Japanese Patent Application Laid-Open (JP-A) No. H8-328024).
However, when the organic film itself contains substances which contaminate the liquid crystal layer, the problem, such as the aforementioned display nonuniformity, which deteriorates the display qualities of the liquid crystal layer cannot be solved.
Also, in such a color liquid crystal display as mentioned above, a step of forming the organic film by a photolithographic method is required in addition to a step of forming the colored layer comprising the black matrix and three colors of R, G and B. This poses the problems of, for example, complicated steps and reduced throughput and yield. Moreover, in the case of using glass beads or plastic beads as a spacer as aforementioned, there is the case where the thickness of the liquid crystal layer is not formed uniformly and the orientation of liquid crystal molecules is disordered when the distribution of the spacer is nonuniform and the spacer are present on display pixels, giving rise to the problem of a reduction in the display efficiencies including contrast ration.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above problems and has an object of providing a color liquid crystal display which is provided with a shielding member disposed between a sealing member and a display zone to prevent the liquid crystal layer from being contaminated with liquid crystal layer-contaminants from the sealing member wherein the above shielding member is formed of a material excluding substances, which adversely affect the liquid crystal layer, and/or can be produced in a simple production process.
The above object can be attained by the following color liquid crystal display of the present invention. According to the first aspect of the present invention, there is provided a color liquid crystal display comprising at least a color filter substrate provided with a colored layer with plural colors formed into a predetermined pattern in a display zone on a transparent substrate, a counter electrode substrate disposed opposite to and with a predetermined gap from the color filter substrate, a sealing member disposed outside of the display zone to seal the gap formed between both substrates, a liquid crystal layer formed by filling a liquid crystal material in the gap formed between both substrates and sealed by the sealing member and a shielding member disposed between the sealing member and the display zone to prevent the liquid crystal material contained in the liquid crystal layer from being contaminated with contaminants from the sealing member, the shielding member being formed of a material which works such that the voltage retention and residual DC (&Dgr;E) of the liquid crystal material after the impurity-extraction treatment is 80% or more and 0.5 V or less respectively.
The color liquid crystal display of the present invention is provided with the shielding member disposed between the sealing member and the display zone in this manner. Hence the liquid crystal material of the liquid crystal layer never be contaminated with contaminants from the sealing member. Moreover, because the shielding member is formed of such a material as aforementioned, the contamination of the liquid crystal material which is caused by the material of the shielding member is prevented, decreasing the possibilities of white unevenness and seizure of the liquid crystal.
In one form of the color liquid crystal display according to the first aspect of the present invention, preferably the shielding member is formed of a material which does not contain pigments, pigment derivatives, dyes or dye derivatives. This is because these pigments, pigment derivatives, dyes or dye derivatives contaminate the liquid crystal material highly possibly though it depends upon the types of these materials and hence there is the case where the shielding member cannot work such that the voltage retention of the liquid crystal material is 80% or more and the residual DC (&Dgr;E) of the liquid crystal material is 0.5 V or less when the liquid crystal material is subjected to impurity-extraction treatment using a material containing a pigment or pigment derivative or a dye or dye derivative.
According to the second aspect of the present invention, there is provided a color liquid crystal display comprising at least a color filter substrate provided with a colored layer with plural colors formed into a predetermined pattern in a display zone on a transparent substrate, a counter electrode substrate disposed opposite to and with a predetermined gap from the color filter substrate, a sealing member disposed outside of the display zone to seal the gap formed between both substrates, a liquid crystal layer formed by filling a liquid crystal material in the gap formed between both substrates and sealed by the sealing member, a columnar convex portion formed so as to keep the gap between both substrates constant and a shielding member disposed between the sealing member and the display zone to prevent the liquid crystal material of the liquid crystal layer from being contaminated with contaminants from the sealing member and formed of the same material as the columnar convex portion.
Since the material of the shielding member is formed of the same material as the columnar convex portion like this, the shielding member can be produced at the same time when the colu
Ishikawa Keizo
Kishimoto Takehide
Nishimoto Takashi
Yamagata Hideaki
Chowdhury Tarifur R.
Dai Nippon Printing Co. Ltd.
Ladas & Parry
Sikes William L.
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