EP0274391A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
A projector using liquid crystal cells
Assignee: Hitachi Ltd
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Filing: 1988-01-07
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Granted: —
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Expires: 2008-01-07
Abstract
Abstract The disclosure relates to a projector having an arrangement of polarizers (30, 48, 58) and liquid crystal cells (32,40,50,60) aligned on the axis of light in the order a first color polarizer (30) colored in red, a first twisted nematic liquid crystal cell, a second twisted nematic liquid crystal cell (40), a second color polarizer (48) colored in green, a third twisted nematic liquid, (50) a neutral polarizer (58) and a Guest-Host type liquid crystal cell (60) 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.
Inventors
- 👤 Katuyuki Hunahata
- 👤 Yoshiharu Nagae
- 👤 Masahiro Takasaka
- 👤 Yuji Mori
- 👤 Minoru Hoshino
- 👤 Yasuyuki Kozima
- 👤 Youhei Saito
- 👤 Kyohei Fukuda
- 👤 Hayao Kozai
- 👤 Tadahiko Hashimoto
- 👤 Yoshiaki Tsuchihashi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 06:15
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/1333; G02F1/1347; G02F1/13471; G02F1/13473; G02F1/13475; G02F1/1335; G02F1/133528; G02F1/133533
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
234 words
A projector having: a light source (24) for generating white light for projection; means (28) for collimating the white light generated by said light source; polarizer means, (30,48,58) arranged on the axis of light, for linearly polarizing the collimated light passing therethrough; liquid crystal cell means (32,40,50,60) arranged with the predetermined positional relationship with said polarizer mean (30,48,58) 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 (68) for projecting light having passed said polarizer means (30,48) and said liquid crystal cell means (32,40,50,60) to reproduce the image on a screen (70) in a full color, characterized in that at least one (60) of said liquid crystal cell means (32,40,50,60) 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 (32,40,50) are non-colored twisted nematic liquid crystal cells; that at least one (30,48) of said polarizer mean (30,48,58) is a color polarizer colored in a color selected from the remaining colors and the remaining polarizers (58) are neutral polarizers; and that a total number of the Guest-Host cell (60) and the color polarizer (30,48) is three, each being colored in a different one of the three primary colors in the additive mixture.
Claim 2
Dependent Claim
234 words
A projector having: a light source (24) for generating white light for projection; means (28) for collimating the white light generated by said light source; polarizer means, (30,48,58) arranged on the axis of light, for linearly polarizing the collimated light passing therethrough; liquid crystal cell means (32,40,50,60) arranged with the predetermined positional relationship with said polarizer mean (30,48,58) 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 (68) for projecting light having passed said polarizer means (30,48) and said liquid crystal cell means (32,40,50,60) to reproduce the image on a screen (70) in a full color, characterized in that at least one (60) of said liquid crystal cell means (32,40,50,60) 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 (32,40,50) are non-colored twisted nematic liquid crystal cells; that at least one (30,48) of said polarizer mean (30,48,58) is a color polarizer colored in a color selected from the remaining colors and the remaining polarizers (58) are neutral polarizers; and that a total number of the Guest-Host cell (60) and the color polarizer (30,48) is three, each being colored in a different one of the three primary colors in the additive mixture.
Claim 3
Dependent Claim
28 words
A projector according to claim 1, wherein said polarizer means includes two color polarizers (30,48) and said liquid crystal cell means includes a single Guest-Host type cell (60).
Claim 4
Dependent Claim
42 words
A projector according to claim 2, wherein one (30) or the two color polarizers (30,48) is colored in red, the other (48) color polarizer is colored in either green or blue, and the Guest-Host cell (60) is colored in the remaining color.
Claim 5
Dependent Claim
15 words
A projector according to claim 3, wherein the Guest-Host cell (60) is colored in blue.
Claim 6
Dependent Claim
101 words
A projector according to claim 2, wherein said polarizer means and said liquid crystal cell means are arranged in the order of a first polarizer (30) colored in a first one of the three primary colors, a first twisted nematic liquid crystal cell (32), a second twisted nematic liquid crystal cell (40), a second polarizer (48) colored in a second one of the three primary colors, a third twisted nematic liquid crystal cell, a third polarizer which is neutral, and a fourth liquid crystal cell which is a Guest-Host type and colored in a third one of the three primary colors.
Claim 7
Dependent Claim
107 words
A projector according to claim 2, wherein said polarizer means and said liquid crystal cell means are constructed by an arrangement of polarizers and liquid crystal cells arranged in the order of a first polarizer (62) colored in a first one of the three primary colors, a first twisted nematic liquid crystal cell (64), a second polarizer (66) colored in a second one of the three primary colors, a second twisted nematic liquid crystal cell (68), a third polarizer (70) which is neutral, and a third liquid crystal cell (72) which is of a Guest-Host type and colored in a third one of the three primary colors.
Claim 8
Dependent Claim
105 words
A projector according to claim 2, wherein said polarizer means and said liquid crystal cell means are constructed by an arrangement of polarizers and liquid crystal cells arranged in the order of a first polarizer(74) which is neutral,a first liquid crystal cell (76) which is of a Guest-Host type and colored in a first one of the three primary colors, a second twisted nematic liquid crystal cell (78), a second polarizer (80) colored in a second one of the three primary colors, a third twisted nematic liquid crystal cell (82), and a third polarizer (84) colored in a third one of the three primary colors.
Claim 9
Dependent Claim
27 words
A projector according to claim 1, wherein said polarizer means includes a single color polarizer (86) and said liquid crystal cell includes two Guest-Host type cells (92,94).
Claim 10
Dependent Claim
123 words
A projector according to claim 1, wherein said polarizer means and said liquid crystal cell means are constructed by an arrangement of polarizers and liquid crystal cells arranged in the order of a first polarizer (86) colored be a first one of the three primary colors, a first twisted nematic liquid crystal cell (88), a second polarizer which is neutral (90), a second liquid crystal cell which is of a Guest-Host type (92) and colored in a second one of the three primary colors, a third liquid crystal cell (94) which is of a Guest-Host type and colored in a third one of the three primary colors, a fourth twisted nematic liquid crystal cell (96), and a third polarizer (98) which is neutral.
References Cited (Backward Citations)
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