Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2000-07-12
2001-09-18
Sikes, William L. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S124000, C349S191000
Reexamination Certificate
active
06292244
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the general field of Liquid Crystal Displays, and more specially to a method of increasing viewing angle and response speeds on a two-domain Chiral Homeotropic LCD with negative compensator.
2. Description of the Prior Art
Currently, the market for LCDs is increasing rapidly. However, the viewing angle and contrast ratio of LCDs are still insufficient for their use in large screen products. For high image quality, these characteristics need to be improved. The Fujitsu Ltd. has proposed a vertical-alignment-mode LCD, recently. Please see the reference “K. Ohmuro, S. Kataoka. T. Sasaki, Y. Koike SID'97 DIGEST p845~p848”. The VA-LCD(vertically aligned LCD) has been implemented by optimizing a vertically aligned mode with a domain-divided structure and an optical compensator. This vertical-alignment-mode LCD has a wide viewing angle of over 70°, a fast response(<25 ms), and a high contrast ratio of over 300, but it still remains some problems. There are disadvantages, for example, the formation of two domain structure by using mask and rubbing process are complex and expensive, the rubbing process also produce ESD (Electrostatic Damage) and particles, further a mask rubbing will result image sticking.
SUMMARY OF THE INVENTION
It is an object of the present invention to solve the aforementioned problems. Another objection of this invention is to provide a method of increasing the viewing angle and response speeds on a two-domain Chiral Homeotropic LCD with negative compensator without a rubbing treatment.
These objects have been achieved by forming a two-domain vertical aligned mode LCD. Further, let the liquid crystal molecules in each of the liquid crystal domains are orientated nearly perpendicular to surfaces of the substrates with a little pre-tilted angle to the normal of the substrates when an electric field is not applied, the tilt angle projected on the azimuthal of substrate between the orientation of liquid crystal molecules in two domains are not equal to 180 degree.
To achieve the aforementioned liquid crystal molecules conditions, there are two methods can be provided. One is using an oblique incident linear polarized ultraviolet light beam process with mask shift to expose the orientation layer twice and forming two-domain structure. Another is using two linear polarized ultraviolet light beam incidents from different direction and a fixed mask to expose the orientation layer in the same time.
These methods can increase the response speed of the liquid crystal molecules and provide a rapid and clean process to avoid the disadvantages that mentioned in the background.
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Kuo Chen-Lung
Liu Hong-Da
Wei Chung-Kuang
Chowdhury Tarifur R.
Industrial Technology Research Institute
McDermott & Will & Emery
Sikes William L.
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