Scanned illumination for light valve video projectors
First Claim
1. In a liquid crystal light valve wherein a liquid crystal is optically addressed by an input write beam that scans the area of said liquid crystal writing scan, and wherein high intensity reading light illuminates the active area of said liquid crystal to be reflected for display, an improved method for illuminating said liquid crystal active area comprising:
- projecting a high intensity reading light to illuminate part of the active area of said liquid crystal, andscanning said illuminated area over said liquid crystal in synchronism with said writing scan;
wherein said steps of projecting and scanning comprise providing a high intensity light source projecting reading light from said source to said liquid crystal, providing a train quasi cylindrical light bending elements, and moving said light bending elements in sequence between said light source and said liquid crystal.
3 Assignments
0 Petitions
Accused Products
Abstract
A video projection system employs a reflective light valve (10) that is optically addressed by an image from a cathode ray tube (12) and provides an output image for projection by means of a high intensity reading light directed to the output face of the liquid crystal light valve. Improved reading illumination is provided by scanning the face of the liquid crystal light valve (10) with a narrow beam of light (80) that moves across the liquid crystal in synchronism with the scanning image from the writing CRT (12). The scanned narrow band (80) of illumination is provided by a circular sequence of three quasi cylindrical lens (56, 58, 60) or mirrors (56a, 58a, 60a) mounted on a rotating wheel (52) and which may be made of sequentially different colors to provide a color display. Rotation of the lens or mirror bearing wheel (52) is synchronized with the vertical sync of the CRT scan, as are the index positions of each of the three lens or mirror segments on the wheel.
84 Citations
31 Claims
-
1. In a liquid crystal light valve wherein a liquid crystal is optically addressed by an input write beam that scans the area of said liquid crystal writing scan, and wherein high intensity reading light illuminates the active area of said liquid crystal to be reflected for display, an improved method for illuminating said liquid crystal active area comprising:
-
projecting a high intensity reading light to illuminate part of the active area of said liquid crystal, and scanning said illuminated area over said liquid crystal in synchronism with said writing scan; wherein said steps of projecting and scanning comprise providing a high intensity light source projecting reading light from said source to said liquid crystal, providing a train quasi cylindrical light bending elements, and moving said light bending elements in sequence between said light source and said liquid crystal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
-
-
12. In a liquid crystal light valve having an input face that is scanned with a scan of input illumination and having an output face with an active area for receiving reading illumination, a method for illuminating said output face comprising:
-
projecting at said output face a reading light beam having a cross section defining a reading area that is smaller than the area of said output face, and moving said area of reading light over said output face in synchronism with said scan of input illumination; wherein said steps of projecting and moving comprise providing a high intensity light source, projecting reading light from said source to said liquid crystal, providing a train of quasi cylindrical light bending elements, and moving said light bending elements in sequence between said light source and said liquid crystal. - View Dependent Claims (13, 14, 15, 16)
-
-
17. A liquid crystal light valve projector comprising:
-
an input face and an output face having an active area, means for scanning said input face with a raster scan of input illumination, and means for illuminating said output face active area comprising; means for projecting at said output face a projection area of reading light that is smaller at said output face than the active area of said output face, and means included in said means for projecting for moving said projection area of reading light over said output face active area in synchronism with said scan of input illumination; said means for projecting including high intensity light source for projecting reading light from said source to said liquid crystal, means for providing a train of quasi cylindrical light bending elements and means for moving said light bending elements in sequence into position between said light source and said liquid crystal. - View Dependent Claims (18, 19, 20, 21, 22)
-
-
23. A liquid crystal light valve projector comprising:
-
liquid crystal light valve having an input face and having an output face with an active area, means for optically addressing the liquid crystal light valve by an input light beam that scans said input face in a writing scan, and high intensity reading light projecting means for illuminating said output face to provide a reflected image for display, said high intensity reading light means comprising; high intensity light source means for generating a high intensity projection beam, means for shaping said projection beam into a reading beam having a reading area smaller than said active area of said output face, and means for causing said reading area to scan said active area in synchronism with said writing scan; said means for projecting including high intensity light source for projecting reading light from said source to said liquid crystal, means for providing a train of quasi cylindrical light bending elements and means for moving said light bending elements in sequence into position between said light source and said liquid crystal. - View Dependent Claims (24, 25, 26, 27, 28)
-
-
29. In a liquid crystal light valve wherein a liquid crystal is optically addressed by an input write beam that scans the area of said liquid crystal in a writing scan, and wherein high intensity reading light illuminates the active area of said liquid crystal to be reflected for display, an improved method for illuminating said liquid crystal active area comprising:
-
projecting a band of reading light to illuminate less than the entire active area of said liquid crystal, and moving said band of reading light over said liquid crystal in synchronism with said writing scan such that the band of reading light illuminates the scanned area of said liquid crystal as it is being optically addressed by said input write beam, wherein said steps of projecting and moving comprise shaping said reading light to a narrow band and repetitively bending said shaped reading light to cause it to scan said liquid crystal active area in synchronism with said writing scan. - View Dependent Claims (30, 31)
-
Specification