Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2000-06-21
2004-09-07
Kim, Robert H. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S158000, C349S161000
Reexamination Certificate
active
06788377
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention relates to a liquid crystal device and a projector using the same.
2. Description of Related Art
A projector is an apparatus for displaying computer images, television images, etc. In a projector, light emitted from an illumination device is modulated by an electro-optical device called a light valve, and the modulated light is projected onto a screen to display an image. As the light valve of such a projector, a liquid crystal device is mainly used.
SUMMARY OF THE INVENTION
It is desirable for an image displayed by a projector to be of higher luminance.
In view of this, the illuminance of the light applied to the liquid crystal device by the illumination device is enhanced, thereby achieving an increase in luminance.
As the luminance of an image increases, a deterioration in contrast occurs and inconsistency in color is generated. This is conspicuous in the four corners of the image.
One exemplary object of this invention is to at least provide a technique for restraining the deterioration in contrast and inconsistency in color, which occurs as a result of an increase in the luminance of an image.
To solve at least a part of the above problem, there is provided, in accordance with one exemplary embodiment of the present invention, a liquid crystal device having a plurality of pixels and adapted to modulate light in accordance with a given image signal. The liquid crystal device may consist of an exit side substrate portion, an entrance side substrate portion opposed to the exit side substrate portion, and a liquid crystal layer placed between the exit side substrate portion and the entrance side substrate portion.
The exit side substrate portion of this exemplary embodiment may consist of an exit side substrate on which a first electrode for driving the liquid crystal layer is formed, and an exit side cover arranged on the exit side with respect to the exit side substrate.
The entrance side substrate portion of this exemplary embodiment may consist of an entrance side substrate on which a second electrode for driving the liquid crystal layer is formed.
In this exemplary embodiment, the absolute value of the coefficient of thermal expansion of the exit side cover is preferably less than 37×10
−7
/° C.
In the above liquid crystal device, the absolute value of the coefficient of thermal expansion of the exit side cover is small, so that it is possible to at least restrain deterioration in contrast and generation of inconsistency in color in an image formed by the liquid crystal device due to birefringence caused by thermal expansion of the exit side cover.
It is also desirable that the absolute value of the coefficient of thermal expansion of the exit side cover be not more than 10×10
−7
/° C.
This makes it possible to further restrain the deterioration in contrast and the generation of color inconsistency in the image due to the thermal expansion of the exit side cover.
In the above first liquid crystal device, it is desirable that the entrance side substrate portion consists of an entrance side cover arranged on the entrance side with respect to the entrance side substrate, the absolute value of the coefficient of thermal expansion of the entrance side cover being less than 37×10
−7
/° C.
Due to this arrangement, the absolute value of the coefficient of thermal expansion of the entrance side cover is small, so that it is possible to at least restrain deterioration in contrast and generation of inconsistency in color in an image formed by the liquid crystal device due to birefringence caused by thermal expansion of the entrance side cover.
It is desirable that the absolute value of the coefficient of thermal expansion of the entrance side cover be not more than 10×10
−7
/° C.
This makes it possible to further restrain the deterioration in contrast and the generation of color inconsistency in the image due to the thermal expansion of the entrance side cover.
In accordance with another exemplary embodiment of the present invention, there is provided a liquid crystal device having a plurality of pixels and adapted to modulate light in accordance with a given image signal. The liquid crystal device may consist of an exit side substrate portion, an entrance side substrate portion opposed to the exit side substrate portion, and a liquid crystal layer placed between the exit side substrate portion and the entrance side substrate portion.
The exit side substrate portion of this exemplary embodiment may consist of an exit side substrate on which a first electrode for driving the liquid crystal layer is formed.
The entrance side substrate portion of this exemplary embodiment may consist of an entrance side substrate on which a second electrode for driving the liquid crystal layer is formed, and an entrance side cover arranged on the entrance side with respect to the entrance side substrate.
In this exemplary embodiment, the absolute value of the coefficient of thermal expansion of the entrance side cover is preferably less than 37×10
−7
/° C.
In the above liquid crystal device, the absolute value of the coefficient of thermal expansion of the entrance side cover is small, so that it is possible to at least restrain deterioration in contrast and generation of inconsistency in color in an image formed by the liquid crystal device due to birefringence caused by thermal expansion of the entrance side cover.
It is also desirable that the absolute value of the coefficient of thermal expansion of the entrance side cover is not more than 10×10
−7
/° C.
This makes it possible to at least further restrain the deterioration in contrast and generation of color inconsistency in the image due to the thermal expansion of the entrance side cover.
In accordance with another exemplary embodiment of the present invention, there is provided a projector which may consist of a liquid crystal device having a plurality of pixels and adapted to emit light after modulating in accordance with a given image signal, an illumination system for irradiating light to the liquid crystal device, and a projection system for projecting light emitted from the liquid crystal device.
The liquid crystal device of this exemplary embodiment may consist of an exit side substrate portion, an entrance side substrate portion opposed to the exit side substrate portion, and a liquid crystal layer placed between the exit side substrate portion and the entrance side substrate portion.
The exit side substrate portion of this exemplary embodiment may consist of an exit side substrate on which a first electrode for driving the liquid crystal layer is formed, and an exit side cover arranged on the exit side with respect to the exit side substrate.
The entrance side substrate portion of this exemplary embodiment may consist of an entrance side substrate on which a second electrode for driving the liquid crystal layer is formed.
In this exemplary embodiment, the absolute value of the coefficient of thermal expansion of the exit side cover is preferably less than 37×10
−7
/° C.
It is also desirable that the absolute value of the coefficient of thermal expansion of the entrance side cover be less than 37×10
−7
/° C.
The above first projector is equipped with the first liquid crystal device of the present invention, so that it is possible to at least restrain deterioration in contrast and generation of color inconsistency due to thermal expansion of the exit side cover and the entrance side cover.
In accordance with another exemplary embodiment of the present invention, there is provided a projector which may consist of a liquid crystal device having a plurality of pixels and adapted to emit light after modulating in accordance with a given image signal, an illumination system for irradiating light to the liquid crystal device, and a projection system for projecting light emitted from the liquid crystal device.
The liquid crystal device of this exemplary embodiment may consist of an exit
Ogawa Yasunori
Okumura Osamu
Takezawa Takeshi
Akkapeddi P. R.
Kim Robert H.
Oliff & Berridg,e PLC
Seiko Epson Corporation
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