Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
1999-12-30
2001-12-25
Ton, Toan (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
Reexamination Certificate
active
06333772
ABSTRACT:
FIELD OF THE INVENTION AND RELATED ART
The present invention relates to a liquid crystal apparatus including a liquid crystal device for displaying various data or information by utilizing a liquid crystal and particularly a liquid crystal apparatus in which a liquid crystal device is appropriately temperature-controlled by utilizing a specific heat deformation member.
Among display apparatus as information exchange means based on human senses, a liquid crystal (display) apparatus excellent in mobility or portability and in energy-saving performance has attracted considerable attention in the present multimedia society and has been extensively developed next to semiconductor devices.
More specifically, as the liquid crystal apparatus, a display apparatus for a notebook-type personal computer has widely been popularized or a light valve for a projector has been tried to be used extensively for realizing large-area display.
Such a liquid crystal apparatus, however, has encountered a problem such that a response speed of a liquid crystal becomes too slow to display high-quality images when the liquid crystal apparatus is driven at a considerably lower temperature. Further, in order to effect high-luminance display, it is necessary to illuminate a liquid crystal panel device) with light having a large luminous energy from illumination means (as a light source), whereby a temperature of the liquid crystal panel is excessively increased (e.g., as indicated by a curve D
2
in
FIG. 3
) to lower a constant, thus failing to effect high-quality image display.
In order to solve the problem, it is necessary to maintain the liquid crystal panel in an appropriate temperature range, e.g., by using:
(1) a method wherein the liquid crystal panel is equipped with a heat dissipation mechanism to diffuse or radiate heat therefrom, or
(2) a method wherein the liquid crystal panel is equipped with a heater, a cooling device and a temperature sensor to control a temperature of the liquid crystal panel.
According to the method (1), however, when the liquid crystal panel is placed in a low-temperature state, e.g., immediately after the liquid crystal panel is activated, the liquid crystal panel temperature is not readily increased due to heat dissipation by the heat dissipation mechanism although the temperature (of the liquid crystal panel) is intended to be increased to at least T1 (e.g., 45° C.) as earlier as possible (in this instance, ta is e.g., 5 min.), as indicated by a curve D
3
shown in FIG.
3
. As a result, a response speed of the liquid crystal is lowered, thus leading to a lower image quality.
Further, the method (1) has a constant heat dissipation effect, so that the above-mentioned heat dissipation mechanism is insufficient to lower the liquid crystal panel temperature in the case where an ambient temperature of the liquid crystal panel is too high, thus lowering a contrast and display qualities.
On the other hand, according to the above-mentioned method (2), in addition to the liquid crystal panel, it is necessary to employ various parts, such as the heater, cooling device and temperature sensor, thus resulting in an increased production cost and a large-sized apparatus.
SUMMARY OF THE INVENTION
In view of the above-mentioned problems, an object of the present invention is to provide a liquid crystal apparatus capable of suppressing a lowering in display image qualities.
Another object of the present invention is to provide a liquid crystal apparatus having solved the above problems relatively inexpensively.
A further object of the present invention is to provide a liquid crystal apparatus having solved the above problems while preventing an increase in apparatus size.
According to the present invention, there is provided a liquid crystal apparatus, comprising:
a liquid crystal panel, illumination means for illuminating the liquid crystal panel, a heat dissipation member disposed with a spacing from the liquid crystal panel, and a heat conductive member disposed between the liquid crystal panel and the heat dissipation member, wherein
the heat conductive member is disposed contactable to at least one of the liquid crystal panel and the heat dissipation member and the liquid crystal apparatus further includes a heat deformation member which is disposed contactable to the heat conductive member and is deformable on receiving heat from the liquid crystal panel, so as to have the heat conductive member contact both the liquid crystal panel and the heat dissipation member thereby forming a heat conductive path between the liquid crystal panel and the heat dissipation member in a first position at a temperature of at least a prescribed temperature of the liquid crystal panel and to have the heat conductive member be separated from at least one of the liquid crystal panel and the heat dissipation member in a second position at a temperature below the prescribed temperature.
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.
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Ishii Takayuki
Mori Shigeki
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Schechter Andrew
Ton Toan
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