US4143947A
Expired / Lapsed
US
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Method for improving the response time of a display device utilizing a twisted nematic liquid crystal composition
Assignee: Amespace Inc
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Filing: 1978-02-21
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Granted: 1979-03-13
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Expires: 1998-02-21
Abstract
Abstract A method for improving the decay time of a display device utilizing a twisted nematic liquid crystal composition by the addition of a controlled amount of optically active material to produce a natural pitch, under field-free conditions, shorter than four times the thickness of the display device cell.
Inventors
- 👤 Siegfried Aftergut
- 👤 Herbert S. Cole, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 19:52
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/137; G02F1/139; G02F1/1396; C; C09; C09K; C09K19/00; C09K19/52; C09K19/58; C09K19/586
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
113 words
A method for improving the spontaneous decay time of a nematic liquid crystal display device having a display cell containing a pair of substrates, comprising the steps of: spacing the facing interior surfaces of said pair of substrates a selected separation distance apart; filling the volume defined between the separated facing interior surfaces of said substrates with a quantity of a nematic liquid crystal composition having only a net positive dielectric anisotropy; and dissolving a preselected amount of an optically-active additive, selected from the group consisting of (-)-methylcyclopentane and d-carvone, in said liquid crystal composition to render the natural pitch thereof larger than the separation distance but smaller than four times that distance.
Claim 2
Independent Claim
113 words
A method for improving the spontaneous decay time of a nematic liquid crystal display device having a display cell containing a pair of substrates, comprising the steps of: spacing the facing interior surfaces of said pair of substrates a selected separation distance apart; filling the volume defined between the separated facing interior surfaces of said substrates with a quantity of a nematic liquid crystal composition having only a net positive dielectric anisotropy; and dissolving a preselected amount of an optically-active additive, selected from the group consisting of (-)-methylcyclopentane and d-carvone, in said liquid crystal composition to render the natural pitch thereof larger than the separation distance but smaller than four times that distance.
Claim 3
Dependent Claim
30 words
The method as set forth in claim 1 wherein said additive is present in an amount of between about 0.1% and about 1.5% by weight of the liquid crystal composition.
Claim 4
Dependent Claim
32 words
The method as set forth in claim 1, further comprising the step of fabricating a coating upon said interior facing surfaces of said substrates to orient the molecules of said liquid composition.
Claim 5
Dependent Claim
28 words
The method as set forth in claim 3, further comprising the step of rotating the orientation coatings of the substrates to be substantially perpendicular each to the other.
Claim 6
Dependent Claim
33 words
The method as set forth in claim 4, wherein said optically-active additive is present in an amount sufficient to cause a 270° twist in the molecules of said composition between said facing surfaces.
Claim 7
Dependent Claim
20 words
The method as set forth in claim 1, wherein said nematic liquid crystal composition is a mixture of cyanophenylbenzoate esters.
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) | 1982-03-12 | 1982-09-11 | 1983-03-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-03-12 | 1986-09-11 | 1987-03-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-03-12 | 1990-09-11 | 1991-03-13 | $7700.00 | Window Closed / Lapsed |