US4989954A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Projection type liquid cyrstal display device
Assignee: Panasonic Holdings Corp
•
Filing: 1988-10-06
•
Granted: 1991-02-05
•
Expires: 2008-10-06
Abstract
Abstract A projection type liquid crystal display device for transmitting three color light beams of RGB through three TN type liquid crystal panels and projecting the transmitted light beams optimizes the RGB transmission characteristics by changing the crossing angles of the polarization axes of a polarizer and an analyzer with respect to the orientation directions of the respective RGB TN cells in specified directions, and also a projection type liquid crystal display device for transmitting a light beam through a TN type liquid crystal panel and projecting the transmitted light beam effects temperature-compensation of the transmission characteristics of the liquid crystal panels by controlling the crossing angle of the polarization axes of a polarizer and an analyzer. Both projection type liquid crystal display devices are relatively simple in the construction, are able to optimize the transmission characteristics of the liquid crystal panels, and have excellent properties in the contrast and in the color reproducibility.
Inventors
- 👤 Kazuo Yokoyama
- 👤 Junichi Asada
- 👤 Hiroshi Watanabe
- 👤 Shoichi Ishihara
- 👤 Sadayoshi Hotta
- 👤 Fumiko Yokotani
- 👤 Yoshihiro Matsuo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 14:42
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; H; H04; H04N; H04N9/00; H04N9/12; H04N9/31; H04N9/3102; G02F1/1333; G02F1/1335; G02F1/133528; G02F1/133531
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
257 words
A projection type liquid crystal display device comprising three liquid crystal panels for transmitting three color light beams of RGB, respectively, a polarizer and an analyzer arranged respectively on the input side and the output side of each of said liquid crystal panels, and an optical system for focusing images of said three liquid crystal panels on a same screen, wherein the device has negative 90° twisted nematic (TN) mode liquid crystal panels in which the polarization axes of said polarizer and said analyzer are aligned so as to be nearly in a state of parallel Nicols, and the gap lengths of the three liquid crystal panels are the same, and crossing angles of polarization axes of said polarizer and said analyzer for each of said three liquid crystal panels are different from each other to minimize transmittance of the three panels that are not driven, wherein the crossing angle θ R of the polarization axes of the R light liquid crystal panel is in the range 0>θ R >-20°, the crossing angle θ B of the polarization axes of the B light liquid crystal panel is in the range of 0<θ B <+20°, and the crossing angle θ G of the polarization axes of the G light liquid crystal panel takes one of respective values satisfying the relations θ G =0 and θ R <θ G <θ B , provided that the direction, in which the polarization axis is rotated to reduce a twist angle of a linearly polarized light beam, is defined to be positive.
Claim 2
Dependent Claim
257 words
A projection type liquid crystal display device comprising three liquid crystal panels for transmitting three color light beams of RGB, respectively, a polarizer and an analyzer arranged respectively on the input side and the output side of each of said liquid crystal panels, and an optical system for focusing images of said three liquid crystal panels on a same screen, wherein the device has negative 90° twisted nematic (TN) mode liquid crystal panels in which the polarization axes of said polarizer and said analyzer are aligned so as to be nearly in a state of parallel Nicols, and the gap lengths of the three liquid crystal panels are the same, and crossing angles of polarization axes of said polarizer and said analyzer for each of said three liquid crystal panels are different from each other to minimize transmittance of the three panels that are not driven, wherein the crossing angle θ R of the polarization axes of the R light liquid crystal panel is in the range 0>θ R >-20°, the crossing angle θ B of the polarization axes of the B light liquid crystal panel is in the range of 0<θ B <+20°, and the crossing angle θ G of the polarization axes of the G light liquid crystal panel takes one of respective values satisfying the relations θ G =0 and θ R <θ G <θ B , provided that the direction, in which the polarization axis is rotated to reduce a twist angle of a linearly polarized light beam, is defined to be positive.
Claim 3
Dependent Claim
117 words
A projection type liquid crystal display device according to claim 1, wherein an angle α R between the polarization axis of the analyzer and an aligning direction of liquid crystal of the input side substrate of the R light panel is in the range 0>α R >-10, the crossing angle θ R of the polarization axes satisfies the relation θ R =2α R , an angle α B between the polarization axis of the analyzer and an aligning direction of liquid crystal of the input side substrate of the B light panel is in the range 0<α B <+10°, and the crossing angle θ B of the polarization axes satisfies the relation θ B =2α B .
Claim 4
Dependent Claim
149 words
A projection type liquid crystal display device comprising a liquid crystal panel for transmitting a light beam, a polarizer and an analyzer arranged respectively on the input side and the output side of said liquid crystal panel, an optical system for focusing the image of said liquid crystal panel on a screen, and means for changing the crossing angle of the polarization axes of said polarizer and said analyzer of said liquid crystal panel in accordance with one of the temperature of said liquid crystal panel and the ambient temperature of said liquid crystal panel so as to optimize the transmission characteristics of said liquid crystal panel, wherein said crossing angle changing means includes one of a shape memory alloy element and a bimetal element connected to one of said polarizer and said analyzer, thereby changing the crossing angle of the polarization axes of said polarizer and said analyzer.
Claim 5
Dependent Claim
149 words
A projection type liquid crystal display device comprising a liquid crystal panel for transmitting a light beam, a polarizer and an analyzer arranged respectively on the input side and the output side of said liquid crystal panel, an optical system for focusing the image of said liquid crystal panel on a screen, and means for changing the crossing angle of the polarization axes of said polarizer and said analyzer of said liquid crystal panel in accordance with one of the temperature of said liquid crystal panel and the ambient temperature of said liquid crystal panel so as to optimize the transmission characteristics of said liquid crystal panel, wherein said crossing angle changing means includes one of a shape memory alloy element and a bimetal element connected to one of said polarizer and said analyzer, thereby changing the crossing angle of the polarization axes of said polarizer and said analyzer.
Claim 6
Dependent Claim
174 words
A projection type liquid crystal display device comprising a liquid crystal panel for transmitting a light beam, a polarizer and an analyzer arranged respectively on the input side and the output side of said liquid crystal panel, an optical system for focusing the image of said liquid crystal panel on a screen, and means for changing the crossing angle of the polarization axes of said polarizer and said analyzer of said liquid crystal panel in accordance with one of the temperature of said liquid crystal panel and the ambient temperature of said liquid crystal panel so as to optimize the transmission characteristics of said liquid crystal panel, wherein said crossing angle changing means includes one of an electric motor and a bimorph cell connected to one of said polarizer and said analyzer, and a signal voltage corresponding to the temperature of said liquid crystal panel is applied to said one of said electric motor and said bimorph cell thereby to change the crossing angle of the polarization axes to said polarizer and said analyzer.
Claim 7
Dependent Claim
174 words
A projection type liquid crystal display device comprising a liquid crystal panel for transmitting a light beam, a polarizer and an analyzer arranged respectively on the input side and the output side of said liquid crystal panel, an optical system for focusing the image of said liquid crystal panel on a screen, and means for changing the crossing angle of the polarization axes of said polarizer and said analyzer of said liquid crystal panel in accordance with one of the temperature of said liquid crystal panel and the ambient temperature of said liquid crystal panel so as to optimize the transmission characteristics of said liquid crystal panel, wherein said crossing angle changing means includes one of an electric motor and a bimorph cell connected to one of said polarizer and said analyzer, and a signal voltage corresponding to the temperature of said liquid crystal panel is applied to said one of said electric motor and said bimorph cell thereby to change the crossing angle of the polarization axes to said polarizer and said analyzer.
References Cited (Backward Citations)
US4368963A
Cited
US4690508A
Cited
US4527864A
Cited
JPS61136795A
Cited
US4759612A
Cited
US4836629A
Cited
US4826311A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-02-04 | 1994-08-06 | 1995-02-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-02-04 | 1998-08-06 | 1999-02-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-02-04 | 2002-08-06 | 2003-02-05 | $7700.00 | Window Closed / Lapsed |