US3723651A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optically-scanned liquid-crystal projection display
Assignee: RCA Corp
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Filing: 1971-12-27
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Granted: 1973-03-27
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Expires: 1991-12-27
Abstract
Abstract A display system is disclosed which includes a multi-layer light control panel having a first transparent electrode, a photoconductor, a normally-transparent liquid crystal, and a second transparent electrode. A laser light beam is modulated with video information and raster scanned to the photoconductor. A direct-current potential is applied across the electrodes during the scanning of a frame, so that spatial variations are created in the light transmissivity of the liquid crystal. During a first portion of a vertical retrace period, a short circuit is placed across the electrodes, and a flash lamp is projected through the light control panel to a display screen. During a second portion of the vertical retrace period, an alternating current potential is applied to the electrodes to restore the liquid crystal to its transparent condition.
Inventors
- 👤 I Gorog
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 18:30
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/135; H; H04; H04N; H04N5/00; H04N5/74; H04N5/7416; H04N5/7441
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
172 words
A display system involving raster scan periods separated by ''''vertical retrace'''' periods, comprising a multi-layer light control panel including, in the order named, a first transparent electrode, a photoconductor, a normally transparent liquid crystal, and a second transparent electrode, means to apply a direct-current potential across said electrodes solely during said raster scan periods, a source of a light beam which is modulated with video information and raster scanned during said raster scan periods onto said photoconductor to cause spatial variations in the light transmissivity of the liquid crystal, a flash lamp on one side of said light control panel and a display screen on the opposite side, and means operative solely during first portions of said vertical retrace periods to connect a short circuit across said electrodes, and to energize said flash lamp to project a flash of light through said light control panel to said display screen, whereby an image is projected, said photoconductor is everywhere rendered conductive, and electric charges are removed from said photoconductor and said liquid crystal.
Claim 2
Dependent Claim
172 words
A display system involving raster scan periods separated by ''''vertical retrace'''' periods, comprising a multi-layer light control panel including, in the order named, a first transparent electrode, a photoconductor, a normally transparent liquid crystal, and a second transparent electrode, means to apply a direct-current potential across said electrodes solely during said raster scan periods, a source of a light beam which is modulated with video information and raster scanned during said raster scan periods onto said photoconductor to cause spatial variations in the light transmissivity of the liquid crystal, a flash lamp on one side of said light control panel and a display screen on the opposite side, and means operative solely during first portions of said vertical retrace periods to connect a short circuit across said electrodes, and to energize said flash lamp to project a flash of light through said light control panel to said display screen, whereby an image is projected, said photoconductor is everywhere rendered conductive, and electric charges are removed from said photoconductor and said liquid crystal.
Claim 3
Dependent Claim
40 words
A display system as defined in claim 1 and, in addition, means operative solely during second portions of said vertical retrace periods to apply an alternating current potential to said electrodes to restore said liquid crystal to its transparent condition.
Claim 4
Dependent Claim
35 words
A display system as defined in claim 2 wherein said source of a scanned light beam and said flash lamp are on the same side of said light control panel having said first transparent electrode.
Claim 5
Dependent Claim
23 words
A display system as defined in claim 3, wherein a projection lens is included between said light control panel and said display screen.
References Cited (Backward Citations)
US3134297A
Cited
US3219756A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-03-26 | 1976-09-25 | 1977-03-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-26 | 1980-09-25 | 1981-03-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-26 | 1984-09-25 | 1985-03-27 | $7700.00 | Window Closed / Lapsed |