US3842275A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Liquid crystal imaging system
Assignee: Xerox Corp
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Filing: 1973-04-26
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Granted: 1974-10-15
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Expires: 1993-04-26
Abstract
Abstract An imaging system which utilizes an imaging member comprising a layer of an imaging composition which exhibits the optical properties of the cholesteric liquid crystalline mesophase is disclosed. The imaging member is provided in a light scattering state, imagewise heated above the isotropic transition temperature and allowed to return to a temperature within the mesomorphic temperature range thus resulting in a visible image which typically remains for extended periods of time. The images can be erased and the imaging members reused.
Inventors
- 👤 J Flannery
- 👤 W Haas
- 👤 J Adams
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 06:47
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/132
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
172 words
An imaging method comprising the steps of: a. prviding a layer of a liquid crystalline imaging composition which exhibits the optical properties of the cholesteric liquid crystalline mesophase and providing said imaging composition at a temperature within its liquid crystalline mesomorphic temperature range; b. applying an electric field uniformly across said imaging composition layer of strength sufficient to place said imaging composition in a light scattering state; c. removing said electric field and applying energy capable of producing a thermal effect in said imaging composition to said layer in imagewise fashion, wherein the temperature of said imaging composition in portions of said layer receiving said energy is raised above the isotropic transition temperature of said imaging composition; and d. cooling the imaged portions of said imaging composition layer to a temperature within the liquid crystalline mesomorphic temperature range of said imaging composition, wherein the imaged portions of said layer assume a light scattering state having a different diffuse scattering density than the background areas of said layer thereby providing a visible image.
Claim 2
Dependent Claim
172 words
An imaging method comprising the steps of: a. prviding a layer of a liquid crystalline imaging composition which exhibits the optical properties of the cholesteric liquid crystalline mesophase and providing said imaging composition at a temperature within its liquid crystalline mesomorphic temperature range; b. applying an electric field uniformly across said imaging composition layer of strength sufficient to place said imaging composition in a light scattering state; c. removing said electric field and applying energy capable of producing a thermal effect in said imaging composition to said layer in imagewise fashion, wherein the temperature of said imaging composition in portions of said layer receiving said energy is raised above the isotropic transition temperature of said imaging composition; and d. cooling the imaged portions of said imaging composition layer to a temperature within the liquid crystalline mesomorphic temperature range of said imaging composition, wherein the imaged portions of said layer assume a light scattering state having a different diffuse scattering density than the background areas of said layer thereby providing a visible image.
Claim 3
Dependent Claim
17 words
The method as defined in claim 1 wherein said imaging composition comprises a cholesteric liquid crystalline material.
Claim 4
Dependent Claim
21 words
The method as defined in claim 1 wherein said imaging composition comprises a mixture of cholesteric and nematic liquid crystalline materials.
Claim 5
Dependent Claim
24 words
The method as defined in claim 1 wherein said imaging composition comprises a mixture of nematic liquid crystalline material and optically active, non-mesomorphic material.
Claim 6
Dependent Claim
19 words
The method as defined in claim 1 wherein said layer of imaging composition is provided on a supporting substrate.
Claim 7
Dependent Claim
23 words
The method as defined in claim 1 wherein said layer of imaging composition is of a thickness not greater than about 250 microns.
Claim 8
Dependent Claim
25 words
The method as defined in claim 6 wherein said layer of imaging composition is of a thickness of from about 1 to about 50 microns.
Claim 9
Dependent Claim
33 words
The method as defined in claim 7 wherein the energy applied to the layer of imaging composition is in the range of from abouT 1 millijoule/cm2 to about 100 millijoules/cm2 of surface area.
Claim 10
Dependent Claim
41 words
The method as defined in claim 8 wherein said imaging composition layer is provided between a pair of electrodes at least one of which is transparent and wherein step (b) is carried out by establishing an electrical field between said electrodes.
Claim 11
Dependent Claim
27 words
The method as defined in claim 9 wherein the energy is applied by exposing the layer of imaging composition to energy through a mask in image configuration.
Claim 12
Dependent Claim
18 words
The method as defined in claim 10 wherein the source of said energy is a gas discharge lamp.
Claim 13
Dependent Claim
16 words
The method as defined in claim 9 wherein the source of said energy is a laser.
Claim 14
Dependent Claim
27 words
The method as defined in claim 1 and further including the step (e) of erasing said image by applying an external force to said imaging composition layer.
Claim 15
Dependent Claim
42 words
The method as defined in claim 13 wherein said step (e) of erasing comprises applying a D.C. electric field uniformly across said imaging composition layer, said electric field being of strength sufficient to place said layer in a uniformly light scattering state.
Claim 16
Dependent Claim
26 words
The method as defined in claim 14 and further including repeating steps (c) through (e) at least one additional time using the same imaging composition layer.
Claim 17
Dependent Claim
31 words
The method as defined in claim 1 wherein said electric field in step (b) has a strength of at least 104 volts/cm of thickness of said layer of liquid crystal composition.
References Cited (Backward Citations)
US3707322A
Cited
US3732429A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-10-14 | 1978-04-15 | 1978-10-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-14 | 1982-04-15 | 1982-10-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-14 | 1986-04-15 | 1986-10-15 | $7700.00 | Window Closed / Lapsed |