US3837730A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Matrix-addressed liquid crystal display
Assignee: AT&T Inc
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Filing: 1973-11-28
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Granted: 1974-09-24
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Expires: 1993-11-28
Abstract
Abstract A row-by-row matrix-addressed display comprises a plurality of liquid crystal cells. Each cell includes a cholesteric-type liquid, with a pleochroic dye dissolved in the liquid crystal material. In operation, each cell has applied thereto either an energizing voltage or an above-zero holding voltage. When energized, a cell is transparent. In response to the holding voltage a cell is either transparent or colored and turbid depending, respectively, on whether or not an energizing voltage was last applied thereto. The clear state at the holding voltage is metastable and eventually decays to the colored turbid condition.
Inventors
- 👤 W Hatfield
- 👤 D White
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 12:43
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/137; G02F1/13731; G02F1/13737
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
122 words
A liquid crystal display device adapted to be included in a matrix-addressed array, said device comprising a cholesteric-type liquid crystal material having positive dielectric anisotropy, a pleochroic dye dissolved in said material, said material being responsive to an applied energizing voltage above a threshold value for transmitting ambient illumination and responsive to an applied holding voltage having a value slightly below said threshold value for absorbing ambient illumination, except that when said applied voltage is first reduced from said energizing value to said holding value said material switches to a metastable state in which the material continues to transmit ambient illumination for a predetermined period of time, and means for applying to said material either said energizing voltage or said holding voltage.
Claim 2
Dependent Claim
134 words
A matrix-addressed display comprising a plurality of liquid crystal devices arranged in an array of rows and columns, each of said devices comprising a cholesteric-type liquid crystal material having positive dielectric anisotropy, a pleochroic dye dissolved in said material, said material being responsive to an applied energizing voltage above a threshold value for transmitting amBient illumination and responsive to an applied holding voltage having a value slightly below said threshold value for absorbing ambient illumination, except that when said applied voltage is first reduced from said energizing value to said holding value said material switches to a metastable state in which the material continues to transmit ambient illumination for a predetermined period of time, and a plurality of overlapping row and column electrodes, said devices being respectively disposed between the overlaps of said electrodes.
Claim 3
Dependent Claim
88 words
A display as in claim 3 further comprising means connected to said electrodes for addressing said devices in a row-by-row fashion, said means being adapted to apply said energizing voltage across each of those devices in a row that is to be rendered transparent and to apply said holding voltage to all other devices in said array, said energizing voltage being greater than the transition voltage of said devices and said holding voltage being less than said transition voltage but greater than the spontaneous voltage of each device.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-09-23 | 1978-03-25 | 1978-09-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-23 | 1982-03-25 | 1982-09-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-23 | 1986-03-25 | 1986-09-24 | $7700.00 | Window Closed / Lapsed |