Liquid crystal cells – elements and systems – With specified nonchemical characteristic of liquid crystal... – Within nematic phase
Reexamination Certificate
2001-06-25
2004-11-23
Flynn, Nathan J. (Department: 2826)
Liquid crystal cells, elements and systems
With specified nonchemical characteristic of liquid crystal...
Within nematic phase
C349S106000, C349S183000
Reexamination Certificate
active
06822723
ABSTRACT:
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to a liquid crystal display and, more particularly, to a liquid crystal display with a wide viewing angle.
(b) Description of the Related Art
Generally, liquid crystal displays have a structure where a liquid crystal layer is sandwiched between two substrates, and an electric field is applied to the liquid crystal to control light transmission. Among the substrates, the top substrate is provided with a common electrode and color filters, and the bottom substrate with thin film transistors and pixel electrodes.
In VA-type (vertically aligned) liquid crystal displays, the liquid crystal molecules are aligned normal to the substrates when an electric field is not applied. In case two polarizer films are arranged perpendicular to each other, the linearly polarized light that has passed through the first polarizer film is completely blocked by the second polarizer film in the absence of an electric field. That is, since such a liquid crystal display exhibits a very low brightness at an “off” state in the normally black mode, it can obtain a relatively higher contrast ratio than the conventional TN liquid crystal displays.
However, when gray scale voltage is applied, the VA-type liquid crystal display involves a narrow viewing angle because of significant difference in retardation of the light depending on the viewing directions.
In order to solve such a problem, it has been proposed that an opening pattern should be formed at the electrode portion. When voltage is applied to the electrode with such an opening pattern, a bent electric field is generated at an area close to the opening pattern, called “fringe field.” The fringe field makes it possible to arrange the liquid crystal molecules in an appropriate manner, thereby widening the viewing angle.
However, in this case, a photolithography process is necessary to form an opening pattern at the common electrode on the color filters. This may damage the underlying color filters, and increase production cost.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a liquid crystal display with a wide viewing angle in simplified processing steps.
It is another object of the present invention to prevent the color filter damage, when fabricating a liquid crystal display.
These and other objects may be achieved by a liquid crystal display with the following features.
The liquid crystal display includes a first substrate, a second substrate facing the first substrate, a liquid crystal layer sandwiched between the first and the second substrates, and first and second electrodes formed at either the first substrate or the second substrate to apply an electric field to the liquid crystal layer. The liquid crystal layer has a barrier of polymer at each pixel region.
The first electrode may be formed on the first substrate, and the second electrode on the second substrate. The first electrode has an opening pattern at each pixel region, and the polymer barrier is positioned corresponding to the opening pattern.
The second substrate is provided with a color filter at each pixel region, and the color filter has a groove corresponding to the opening pattern of the pixel electrode.
A protrusion is formed on the opening pattern. Alternatively, a protrusion or a hollow may be formed under the opening pattern.
A first vertical alignment layer is formed on the first electrode, and a second vertical alignment layer on the second substrate.
The liquid crystal layer bears a negative dielectric anisotropy.
In a method of fabricating the liquid crystal display, the first and the second substrates are arranged to face each other. A liquid crystal is injected in-between the first and the second substrates to form a liquid crystal layer. A polymer barrier is formed at the liquid crystal layer.
The liquid crystal layer contains monomers having a property of transmitting phases when UV light is illuminated.
The method further includes the steps of forming a first electrode on the first substrate, and forming a second electrode on the second substrate. At least one of the first and the second electrodes has an opening pattern.
The method further includes the step of forming color filters either at the first substrate or at the second substrate such that each color filter has a groove corresponding to the opening pattern.
The UV light is illuminated to the monomers through the groove at the step of forming the polymer barrier.
The method further includes the step of forming a protrusion on the opening pattern, or forming a protrusion or a hollow under the opening pattern.
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Kim Jae-Hoon
Song Jang-Kun
Flynn Nathan J.
McGuireWoods LLP
Sefer Ahmed N.
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