US3796999A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Locally erasable thermo-optic smectic liquid crystal storage displays
Assignee: AT&T Inc
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Filing: 1972-10-19
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Granted: 1974-03-12
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Expires: 1992-10-19
Abstract
Abstract This invention provides a liquid crystal optical display apparatus, which can be both selectively written and selectively erased. Both write-in and erase steps involve the use of localized thermal heating, by means of an infrared laser for example. The localized ''''written'''' state of the liquid crystal is characterized by a significantly greater optical scattering than the localized ''''erased'''' state of the crystal. Depending upon the conditions under which a localized area of the liquid crystal is cooled, the final state of the local heat-treated area becomes the non-scattering erase state or the scattering written state, thus affording localized erase or write-in, as desired. The factors which determine this final state (scattering vs. nonscattering) include the rate of cooling. In turn, the rate of cooling can be controlled by the rate of laser scan or by the cross section of the laser beam used for the heating of the selected areas of the liquid crystal. Additionally, the final state can be affected by the presence or absence of applied fields across the liquid crystal during the cooling period.
Inventors
- 👤 F Kahn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 21:57
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/132; G02F1/137; G02F1/13781; G09; G09G; G09G3/00; G09G3/02; G09G3/20; G09G3/34; G09G3/36; G09G3/3603; G11; G11C; G11C13/00; G11C13/04; G11C13/048
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
116 words
The method of storing information in a film which comprises the steps of (a) raising the temperature oF a first portion of the film initially at a first ambient temperature; (b) allowing said first portion of the film to cool at a first rate to the ambient temperature; (c) raising the temperature of a second portion of the film including at least a part of the first portion of the film; and (d) allowing the second portion to cool at a second rate to the first ambient temperature, whereby an optical property of the film in the second portion becomes different from said property in the first portion of the film prior to the step (c).
Claim 2
Independent Claim
116 words
The method of storing information in a film which comprises the steps of (a) raising the temperature oF a first portion of the film initially at a first ambient temperature; (b) allowing said first portion of the film to cool at a first rate to the ambient temperature; (c) raising the temperature of a second portion of the film including at least a part of the first portion of the film; and (d) allowing the second portion to cool at a second rate to the first ambient temperature, whereby an optical property of the film in the second portion becomes different from said property in the first portion of the film prior to the step (c).
Claim 3
Dependent Claim
14 words
The method recited in claim 1 in which the film is a liquid crystal.
Claim 4
Dependent Claim
26 words
The method recited in claim 2 in which essentially the entire film is in the smectic state at the ambient temperature prior to the step (a).
Claim 5
Independent Claim
118 words
The method of storing information in a film which comprises the steps of (a) raising the temperature of a first portion of the film initially at a first ambient temperature; (b) cooling said first portion of the film; (c) raising the temperature of a second portion including at least a part of the first portion of the film; and (d) cooling the second portion in the presence of an electric field which is significantly different from any electric field applied to the film during the cooling of the first portion, whereby, an optical property of the film in the second portion becomes different from said property in the first portion of the film prior to the step (c).
Claim 6
Independent Claim
118 words
The method of storing information in a film which comprises the steps of (a) raising the temperature of a first portion of the film initially at a first ambient temperature; (b) cooling said first portion of the film; (c) raising the temperature of a second portion including at least a part of the first portion of the film; and (d) cooling the second portion in the presence of an electric field which is significantly different from any electric field applied to the film during the cooling of the first portion, whereby, an optical property of the film in the second portion becomes different from said property in the first portion of the film prior to the step (c).
Claim 7
Dependent Claim
14 words
The method recited in claim 4 in which the film is a liquid crystal.
Claim 8
Dependent Claim
24 words
The method recited in claim 5 in which the film is a smectic liquid crystal at the ambient temperature prior to the step (a).
Claim 9
Dependent Claim
137 words
An optical information storage device which includes (a) a liquid crystal film; and (b) means for selectively heating the film in succession, including a first and a second beam having first and second cross sections, said beams having first and second scanning rates respectively across the film, in order to heat, respectively, a first portion of the film and a second portion of the film including part or all of the first portion of the film, the scanning rates and cross sections of the beams being selected such that the second portion of the film cools at a different rate than the first portion of the film, whereby an optical property of the film in the second portion becomes different from said property in the second portion of the film in the absence of the second beam.
Claim 10
Dependent Claim
137 words
An optical information storage device which includes (a) a liquid crystal film; and (b) means for selectively heating the film in succession, including a first and a second beam having first and second cross sections, said beams having first and second scanning rates respectively across the film, in order to heat, respectively, a first portion of the film and a second portion of the film including part or all of the first portion of the film, the scanning rates and cross sections of the beams being selected such that the second portion of the film cools at a different rate than the first portion of the film, whereby an optical property of the film in the second portion becomes different from said property in the second portion of the film in the absence of the second beam.
Claim 11
Dependent Claim
123 words
An optical information storage device which includes (a) a liquid crystal film; (b) means for selectively heating the film including first and second beams having first and second cross sections, said beams having first and second scanning rates respectively across the film, in order to heat a first portion of the film and a second portion of the film including part or all of the first portion thereof; (c) a source of electric voltage; and (d) means for applying the electric voltage to the film while applying the first or the second beams, whereby an optical property of the film in the second portion becomes different from said property in the second portion of the film in the absence of the second beam.
Claim 12
Dependent Claim
123 words
An optical information storage device which includes (a) a liquid crystal film; (b) means for selectively heating the film including first and second beams having first and second cross sections, said beams having first and second scanning rates respectively across the film, in order to heat a first portion of the film and a second portion of the film including part or all of the first portion thereof; (c) a source of electric voltage; and (d) means for applying the electric voltage to the film while applying the first or the second beams, whereby an optical property of the film in the second portion becomes different from said property in the second portion of the film in the absence of the second beam.
Claim 13
Dependent Claim
105 words
An optical storage device which includes (a) a liquid crystal at a first temperature under ambient operating conditions; (b) means for heating in succession first and second portions of the crystal, in order to heat said portions to temperatures above the first temperature, the second portion including at least a portion of the first region; and (c) means for applying an electric field to the crystal while the second portion cools to the first temperature, whereby an optical property of the film in the second portion becomes different from said property in the second portion of the film in the absence of the second beam.
Claim 14
Dependent Claim
105 words
An optical storage device which includes (a) a liquid crystal at a first temperature under ambient operating conditions; (b) means for heating in succession first and second portions of the crystal, in order to heat said portions to temperatures above the first temperature, the second portion including at least a portion of the first region; and (c) means for applying an electric field to the crystal while the second portion cools to the first temperature, whereby an optical property of the film in the second portion becomes different from said property in the second portion of the film in the absence of the second beam.
Claim 15
Dependent Claim
83 words
An optical storage apparatus which includes (a) a liquid crystal in the smectic state at a first ambient temperature; and (b) means for heating a selected portion of the crystal, in order to heat said portion to a temperature sufficient to bring said portion Of the crystal into a state other than the smectic state, so that when the said portion cools to the first ambient temperature said second portion has a significantly different optical property from the remainder of the liquid crystal.
Claim 16
Dependent Claim
83 words
An optical storage apparatus which includes (a) a liquid crystal in the smectic state at a first ambient temperature; and (b) means for heating a selected portion of the crystal, in order to heat said portion to a temperature sufficient to bring said portion Of the crystal into a state other than the smectic state, so that when the said portion cools to the first ambient temperature said second portion has a significantly different optical property from the remainder of the liquid crystal.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-03-11 | 1977-09-10 | 1978-03-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-11 | 1981-09-10 | 1982-03-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-11 | 1985-09-10 | 1986-03-12 | $7700.00 | Window Closed / Lapsed |