Projection type liquid cyrstal display device

• US 4,989,954 A
• Filed: 10/06/1988
• Issued: 02/05/1991
• Est. Priority Date: 10/09/1987
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited 1006 OAZA Kadoma-Shi Osaka Japan
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Matsuo, Yoshihiro, Ishihara, Shoichi, Hotta, Sadayoshi, Watanabe, Hiroshi, Yokoyama, Kazuo, Asada, Junichi, Yokotani, Fumiko
• Primary Examiner(s): Miller, Stanley D.
• Assistant Examiner(s): MAI, HUY KIM
• Application Number:
  US07/254,244
• Time in Patent Office: 852 Days
• Field of Search: 350/331 T, 350/331 R, 350/334, 350/335, 350/33 T, 350/339 F, 353/122
• US Class Current: 349/72
• CPC Class Codes: G02F 1/133531 characterised by the arrangement of polariser or analyser axes
• CPC Class Codes: H04N 9/3102 using two-dimensional electronic spatial light modulators micromechanical modulators as such G02B26/0833; liquid crystal modulators as such G02F1/13

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.

Claims

1. 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.

2. 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.

3. 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.

4. 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.