Patent US4053985A successfully refreshed from Google Patents.
Patent US5777789A successfully refreshed from Google Patents.
US5777789A
Expired / Lapsed
US
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Efficient optical system for a high resolution projection display employing reflection light valves
Assignee: International Business Machines Corp
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Filing: 1997-09-19
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Granted: 1998-07-07
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Expires: 2017-09-19
Abstract
Abstract An optical system is described consisting of reflection birefringent light valves, polarizing beam splitter, color image combining prisms, illumination system, projection lens, filters for color and contrast control, and screen placed in a configuration offering advantages for a high resolution color display. The illumination system includes a light tunnel having a cross-sectional shape corresponding to the geometrical shape of the spacial light modulator to optimize the amount of light projected onto the screen.
Inventors
- 👤 George Liang-Tai Chiu
- 👤 Thomas Mario Cipolla
- 👤 Fuad Elias Doany
- 👤 Derek Brian Dove
- 👤 Alan Edward Rosenbluth
- 👤 Rama Nand Singh
- 👤 Janusz Stanislaw Wilczynski
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 22:46
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/74; H04N9/00; H04N9/12; H04N9/31; H04N9/3102; H04N9/3105
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
273 words
An apparatus for projecting an image onto a screen comprising: a light source for providing light; a polarizing beam splitting means for splitting the light into first and second polarizations; a prism assembly having a plurality of output faces for splitting the light from said polarizing beam splitting means of said first polarization into a plurality of colors and directing each color through a corresponding one of said output faces and for recombining said plurality of colors reflected back into said prism assembly through each of said respective output faces to form a recombined colored light; a plurality of spatial light modulators, one of said plurality of spatial light modulators having a face defining a geometric shape; a light tunnel between said light source and said plurality of spatial light modulators for providing light from said light source exiting said tunnel with an uniform light intensity, said light tunnel having a cross-sectional shape corresponding to said geometrical shape; said plurality of spatial light modulators being positioned adjacent said output faces of said prism assembly for rotating the polarization of said plurality of colors directed through each of said output faces of said prism assembly to form rotated colored lights and reflecting said rotated colored lights back into said prism assembly through said output faces for recombining therein to form said recombined colored light; and a projection lens, said polarizing beam splitting means splitting said recombined colored light directed therein from said prism assembly into first and second polarizations and directing light of said second polarization into said projection lens for projecting said light of said second polarization as the image onto the screen.
Claim 2
Independent Claim
273 words
An apparatus for projecting an image onto a screen comprising: a light source for providing light; a polarizing beam splitting means for splitting the light into first and second polarizations; a prism assembly having a plurality of output faces for splitting the light from said polarizing beam splitting means of said first polarization into a plurality of colors and directing each color through a corresponding one of said output faces and for recombining said plurality of colors reflected back into said prism assembly through each of said respective output faces to form a recombined colored light; a plurality of spatial light modulators, one of said plurality of spatial light modulators having a face defining a geometric shape; a light tunnel between said light source and said plurality of spatial light modulators for providing light from said light source exiting said tunnel with an uniform light intensity, said light tunnel having a cross-sectional shape corresponding to said geometrical shape; said plurality of spatial light modulators being positioned adjacent said output faces of said prism assembly for rotating the polarization of said plurality of colors directed through each of said output faces of said prism assembly to form rotated colored lights and reflecting said rotated colored lights back into said prism assembly through said output faces for recombining therein to form said recombined colored light; and a projection lens, said polarizing beam splitting means splitting said recombined colored light directed therein from said prism assembly into first and second polarizations and directing light of said second polarization into said projection lens for projecting said light of said second polarization as the image onto the screen.
Claim 3
Dependent Claim
16 words
The apparatus of claim 1 wherein said light tunnel is comprised of a plurality of mirrors.
Claim 4
Dependent Claim
21 words
The apparatus of claim 2 wherein said light tunnel is comprised of four mirrors assembled to form a hollow rectangular tunnel.
Claim 5
Dependent Claim
14 words
The apparatus of claim 1 wherein said light tunnel is comprised of solid glass.
Claim 6
Dependent Claim
31 words
The apparatus of claim 1 further including a relay lens system for focusing light from said light tunnel onto the face of said one of said plurality of spatial light modulators.
Claim 7
Dependent Claim
21 words
The apparatus of claim 1 further including means for directing light from said light tunnel into said polarizing beam splitting means.
Claim 8
Dependent Claim
19 words
The apparatus of claim 1 wherein said plurality of spatial light modulators include a liquid crystal light valve assembly.
Claim 9
Dependent Claim
26 words
The apparatus of claim 1 wherein said prism assembly is comprised of three solid glass prisms forming two color separating surfaces located internally of said assembly.
Claim 10
Dependent Claim
29 words
The apparatus of claim 1 wherein said polarizing beam splitting means is comprised of two solid glass prisms forming a polarization separating surface internally of said beam splitting means.
Claim 11
Dependent Claim
27 words
The apparatus of claim 1 further including an illumination assembly for filtering out ultraviolet and infrared light from said source prior to said light entering said tunnel.
Claim 12
Dependent Claim
28 words
The apparatus of claim 1, wherein said cross-sectional shape of said light tunnel corresponding to said geometric shape substantially prevents loss of light in corners of said image.
References Cited (Backward Citations)
US3202039A
Cited
US3602637A
Cited
US3832029A
Cited
US4097128A
Cited
US4687301A
Cited
US4744615A
Cited
US4916529A
Cited
US5096280A
Cited
US5260815A
Cited
US5022750A
Cited
US5181130A
Cited
US5109465A
Cited
US5130826A
Cited
US5251068A
Cited
US5196926A
Cited
US5321789A
Cited
US5206674A
Cited
US5270804A
Cited
EP0523988A1
Cited
US5434406A
Cited
US5475513A
Cited
EP0676902A2
Cited
EP0691552A2
Cited
US5621486A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-07-06 | 2002-01-05 | 2002-07-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-07-06 | 2006-01-05 | 2006-07-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-07-06 | 2010-01-05 | 2010-07-07 | $7700.00 | Window Closed / Lapsed |