Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
1999-05-03
2001-02-20
Dudek, James A. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
Reexamination Certificate
active
06191839
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to liquid crystal displays (LCDs) and more particularly relates to LCD heaters and even more particularly relates to controls for LCD heaters.
In the past, LCD heater plates have been incorporated to provide a uniform temperature across the LCD surface. The heater has typically been deposited material such as indium tin oxide (ITO) applied to a glass cover placed adjacent to the liquid crystal layer within the display. Electrical current is then passed through the ITO coating across the display face to generate uniform heating.
Available temperature sensors, for providing feedback to thermal controls functions, are opaque and too large to be placed within the stacked layers comprising the display. Consequently, the thermal sensors have been placed about the periphery to provide information about the temperature of the LCD material. This method has limitations for determining the temperature of the central portion of the display and extent of thermal gradients present.
Thermal gradients form across the surface of the display due to non-uniform flow of heat from the liquid crystal material to the adjacent environment and display housing.
Consequently, there exists a need for improved thermal sensing across the LCD assembly, in order to provide better thermal management of the display.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved image for LCDs.
It is a feature of the present invention to include a thermal sensor disposed inwardly of the LCD periphery.
It is an advantage of the present invention to better assess the temperature gradient existing across an LCD viewing surface.
It is another object of the present invention to reduce visual discontinuities at interior portions of the LCD viewing surface.
It is another feature of the present invention to include a thermal sensor device made of transparent materials.
It is another advantage of the present invention to reduce visual discontinuities caused by placing opaque materials in the viewing surface of an LCD.
It is yet another object of the present invention to provide an LCD heater control device which is readily manufacturable.
It is yet another feature of the present invention to include a void in a heater surface across the viewing surface of an LCD.
The present invention is a method and apparatus for heating an LCD which is designed to satisfy the aforementioned needs, provide the previously stated objects, include the above-listed features and achieve the already articulated advantages.
Accordingly, the present invention is a method and apparatus providing a thermal sensor in an interior portion of an LCD viewing surface and controlling the LCD based upon an output of the sensor that is substantially invisible to the unaided eye.
REFERENCES:
patent: 5694191 (1997-12-01), Strathman et al.
patent: 5775221 (1998-07-01), Baumgartner, Jr.
patent: 5886736 (1999-03-01), Wolkowicz et al.
patent: 5914764 (1999-06-01), Henderson
patent: 5936696 (1999-08-01), Daijogo
patent: WO 98/29779 (1998-07-01), None
Briley Joseph H.
Davis Gregory E.
Dudek James A.
Eppele Kyle
Jensen Nathan O.
O'Shaughnessy J. P.
Rockwell Collin, Inc.
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