Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2001-07-20
2003-09-09
Parker, Kenneth (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S111000, C349S106000
Reexamination Certificate
active
06618108
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a liquid crystal display device which displays images using liquid crystals as an optical shutter.
2. Description of the Related Art
Active matrix-type liquid crystal display devices which adopt the twisted nematic display method (hereafter called the “TN display method”) are well known. A liquid crystal display device adopting this method has a configuration in which two transparent electrodes driving the liquid crystals are arranged in mutual opposition on a substrate surface. In this configuration, alignment films are deposited covering the wiring formed on the active matrix substrate and opposing substrate, and rubbing processing is performed such that the alignment directions of the films are orthogonal. When the active matrix substrate uses TFTs as the active elements, it is sometimes called a TFT substrate. Because the opposing substrate normally comprises a color filter, it is sometimes called a color filter substrate. Then, these two substrates are bonded together with an adhesive called a sealing agent, and after injection of the liquid crystals, the injection aperture is sealed with resin. The liquid crystal molecules are tilted forward slightly in the rubbing direction—that is, they are inclined so as to face upward in the rubbing direction and downward in the opposite direction (this is called a pretilt), aligned along the active matrix substrate and along the opposing substrate.
In a liquid crystal display device with such a configuration, there are such problems as display unevenness and reduced contrast arising from light leakage due to alignment defects such as reverse tilt, occurring in regions where the horizontal-direction electric field between wiring and pixel electrodes opposes the above-described pretilt of the liquid crystal molecules.
An effective means of resolving such problems is to use the color filter pixel black matrix to block light leakage caused by reverse tilt and other alignment irregularities.
However, in peripheral parts of the panel display area, impurities separating from the sealing agent impede the alignment of liquid crystals, and so there has been the problem that the area where the alignment defects are occurred due to reverse tilt or similar is much larger than near the center of the display area.
SUMMARY OF THE INVENTION
In view of the foregoing, it is an object of the present invention to provide a liquid crystal display device in which the occurrence of light leakage due to alignment anomalies arising from the horizontal-direction electric field between the signal lines and scanning lines and the pixel electrodes can be suppressed, and display quality can be enhanced without detracting from manufacturing efficiency or yield and without reducing the brightness of the liquid crystal display device.
It is another object of the present invention to provide a liquid display device in which the reduction of the brightness of the liquid display device in panel peripheral region is not noticed by an observer.
According to one aspect of the present invention, for achieving the above-mentioned objects, there is provided an active matrix-type liquid crystal display device, having a black matrix which prevents light leakage between pixels, wherein the apertures in the black matrix in panel peripheral regions are made smaller than the apertures in the black matrix in the panel center region.
According to another object of the present invention, there is provided a liquid crystal display device, wherein the apertures in the black matrix in the peripheral regions of the panel are made smaller in stages as moving away from the center region.
Consequently, the liquid crystal display devices of the aspects of this invention are in which, by increasing the pixel black matrix width on the opposing color filter substrate in the panel peripheral regions compared with the panel center region, the occurrence of light leakage due to alignment anomalies arising from the horizontal-direction electric field between the signal lines and scanning lines and the pixel electrodes can be suppressed, and display quality can be enhanced without detracting from manufacturing efficiency or yield and without reducing the brightness of the liquid crystal display device, so that this invention affords excellent advantages.
The above and further objects and novel features of the invention will more fully appear from the following detailed description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are for purpose of illustration only and are not intended as a definition of the limits of the invention.
REFERENCES:
patent: 5689320 (1997-11-01), Okada et al.
patent: 5818554 (1998-10-01), Hiyama et al.
patent: 6151096 (2000-11-01), McDonnell et al.
patent: 6184967 (2001-02-01), Lagerwall et al.
patent: 6424394 (2002-07-01), Morii
patent: 6456354 (2002-09-01), Greene et al.
Advanced Display Inc.
Chung David
Parker Kenneth
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