Projector using guest-host liquid crystal cells for improved color purity
First Claim
1. A projector having:
- a light source for generating white light for projection;
means for collimating the white light generated by said light source;
polarizer means, arranged on the axis of light, for linearly polarizing the collimated light passing therethrough;
liquid crystal cell means arranged with the predetermined positional relationship with said polarizer means on the same axis of light and selectively excited or de-excited in accordance with video signals of an image to be reproduced to control the polarization plane of light passing therethrough; and
means for projecting light having passed said polarizer means and said liquid crystal cell means to reproduce the image on a screen in a full color,characterized inthat at least one of said liquid crystal cell means is a Guest-Host type cell which is colored in a color selected from among three primary colors of an additive mixture and the remaining liquid crystal cell means are non-colored twisted nematic liquid crystal cells;
that at least one of said polarizer means is a color polarizer colored in a color selected from the remaining colors and the remaining polarizers are neutral polarizers; and
that a total number of the Guest-Host cell and the color polarizer is three, each being colored in a different one of the three primary colors in the additive mixture.
3 Assignments
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Accused Products
Abstract
The disclosure relates to a projector having an arrangement of polarizers and liquid crystal cells aligned on the axis of light in the order a first color polarizer colored in red, a first twisted nematic liquid crystal cell, a second twisted nematic liquid crystal cell, a second color polarizer colored in a green, a third twisted nematic liquid, a neutral polarizer and Guest-Host type colored in blue. Since, according to this, a polarizer having inferior color characteristics can be replaced by a Guest-Host type liquid crystal cell, the excitation purity and the scope of color reproduction are improved. Further, since the mixture of color is additive, the brightness of the reproduced color is also much improved.
92 Citations
17 Claims
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1. A projector having:
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a light source for generating white light for projection; means for collimating the white light generated by said light source; polarizer means, arranged on the axis of light, for linearly polarizing the collimated light passing therethrough; liquid crystal cell means arranged with the predetermined positional relationship with said polarizer means on the same axis of light and selectively excited or de-excited in accordance with video signals of an image to be reproduced to control the polarization plane of light passing therethrough; and means for projecting light having passed said polarizer means and said liquid crystal cell means to reproduce the image on a screen in a full color, characterized in that at least one of said liquid crystal cell means is a Guest-Host type cell which is colored in a color selected from among three primary colors of an additive mixture and the remaining liquid crystal cell means are non-colored twisted nematic liquid crystal cells; that at least one of said polarizer means is a color polarizer colored in a color selected from the remaining colors and the remaining polarizers are neutral polarizers; and that a total number of the Guest-Host cell and the color polarizer is three, each being colored in a different one of the three primary colors in the additive mixture. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A projector having:
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a light source for generating white light for projection; means for collimating the white light generated by said light source; three polarizer means for linearly polarizing the collimated light passing therethrough, two of said three polarizer means being color polarizers colored in two colors selected from among three primary colors of the additive color mixture, respectively, and the other of said three polarizer means being a neutral polarizer; at least three liquid crystal cell means, selectively and repeatedly excited or de-excited in accordance with video signals of an image to be reproduced to control the polarization plane of light passing therethrough, one of said at least three liquid crystal cell means being a Guest-Host type cell colored in the remaining color of the three primary colors and the remaining liquid crystal cell means being noncolored twisted nematic liquid crystal cells; said polarizer means and said liquid cell means being arranged on the same axis of light in such a positional relationship that, in response to the video signals, said liquid crystal cell means control the polarization plane of light incident on the color polarizers and Guest-Host type cell to color the light passing therethrough in a corresponding color; and means for projecting the light having passed through said polarizer means and liquid crystal cell means to reproduce the image on a screen in full color. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A projector having:
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a light source for generating white light for projection; means for collimating the white light generated by said light source; three polarizer means for linearly polarizing the collimated light passing therethrough, one of said three polarizer means being color polarizer colored in a color selected from among three primary colors of the additive color mixture and the other two polarizer means being neutral polarizers; four liquid crystal cell means, selectively and repeatedly excited or de-excited in accordance with video signals of an image to be reproduced to control the polarization plane of light passing therethrough, two of said four liquid crystal cell means being Guest-Host type cells colored in the remaining two colors of the three primary colors, respectively, and the remaining two of said four liquid crystal cell means being noncolored twisted nematic liquid crystal cells; said polarizer means and liquid crystal cell means being arranged on the same axis of light in such a positional relationship that, in response to the video signals, said liquid crystal cell means control the polarization plane of light incident on the color polarizer and Guest-Host type cells to color the light passing therethrough in a corresponding color; and means for projecting the light having passed through said polarizer means and liquid crystal cell means to reproduce the image on a screen. - View Dependent Claims (17)
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Specification