US4231068A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical screens
Assignee: BTG International Ltd
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Filing: 1978-06-12
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Granted: 1980-10-28
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Expires: 1998-06-12
Abstract
Abstract A cathode ray tube has an optical screen formed of a series of strips aligned with the writing direction of the cathode ray tube raster. The strips each comprise a layer of electro-optical material, and are electrically interconnected with the cathode ray tube circuitry so that each strip is transparent when the raster is writing on a cathode ray tube display face behind it. The electro-optical material is preferably a liquid crystal material.
Inventors
- 👤 Geoffrey H. Hunt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 21:53
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/137; G02F1/139; G02F1/1393; G02F1/1313; H; H01; H01J; H01J29/00; H01J29/86; H01J29/89; H01J29/896; H01J2229/00; H01J2229/89; H01J2229/8926
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
78 words
An optical screen for use with a cathode ray tube having a display face and a raster, comprising a series of parallel strips aligned with the writing direction of said raster, each of said parallel strips comprising a layer of electro-optical substance, and means for sequentially varying a voltage applied across said strips so that each strip is transparent when said raster is writing behind it and becomes light absorbent when said raster is not writing behind it.
Claim 2
Dependent Claim
78 words
An optical screen for use with a cathode ray tube having a display face and a raster, comprising a series of parallel strips aligned with the writing direction of said raster, each of said parallel strips comprising a layer of electro-optical substance, and means for sequentially varying a voltage applied across said strips so that each strip is transparent when said raster is writing behind it and becomes light absorbent when said raster is not writing behind it.
Claim 3
Dependent Claim
16 words
An optical screen as claimed in claim 1 wherein the level of said voltage is varied.
Claim 4
Dependent Claim
18 words
An optical screen as claimed in claim 1 wherein said voltage is alternating and its frequency is varied.
Claim 5
Dependent Claim
20 words
An optical screen as claimed in claim 1, 2 or 3 wherein said optical screen also comprises an anti-reflection coating.
Claim 6
Dependent Claim
29 words
An optical screen as claimed in claim 1, 2 or 3 wherein said electro-optical substance is a liquid crystal material sandwiched between two plates of transparent electrically conducting material.
Claim 7
Dependent Claim
15 words
An optical screen as claimed in claim 5 wherein said liquid crystal material is nematic.
Claim 8
Dependent Claim
21 words
An optical screen as claimed in claim 6 wherein said nematic liquid crystal material is arranged in a twisted nematic form.
Claim 9
Dependent Claim
25 words
An optical screen as claimed in claim 7 wherein said layer of liquid crystal material is sandwiched between at least two sheets of polaroid material.
Claim 10
Dependent Claim
29 words
An optical screen as claimed in claim 7 wherein a pleochroic dye is dissolved in said liquid crystal material and said screen further comprises a sheet of polaroid material.
Claim 11
Dependent Claim
21 words
An optical screen as claimed in claim 6 wherein said nematic liquid crystal material is arranged to exhibit a Freedericksz effect.
Claim 12
Dependent Claim
25 words
An optical screen as claimed in claim 10 wherein said layer of liquid crystal material is sandwiched between at least two sheets of polaroid material.
Claim 13
Dependent Claim
29 words
An optical screen as claimed in claim 10 further comprising one or more sheets of birefringent material located between at least one of said plates and said electro-optical substance.
Claim 14
Dependent Claim
29 words
An optical screen as claimed in claim 10 wherein a pleochroic dye is dissolved in said liquid crystal material and said screen further comprises a sheet of polaroid material.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-10-28 | 1984-04-28 | 1984-10-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-10-28 | 1988-04-28 | 1988-10-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-10-28 | 1992-04-28 | 1992-10-28 | $7700.00 | Window Closed / Lapsed |