Patent US4997264A successfully refreshed from Google Patents.
US4997264A
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Ferroelectric liquid crystal devices having a high surface tilt
Assignee: Qinetiq Ltd
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Filing: 1988-12-01
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Granted: 1991-03-05
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Expires: 2008-12-01
Abstract
Abstract A liquid crystal display device with a fast switching time and bistability comprises a layer of a chiral smectic material between cell walls. Electrodes on the walls allow the material to be switched between two states by application of positive and negative voltage pulses. Rapid switching is due to the ferro electric effect. Good alignment and uniformity of display is achieved by using an alignment giving a high, 5°-45°, tilt to the liquid crystal molecules. Alignment may be provided by oblique evaporate of silicon monoxide at a glancing angle of up to 15°.
Inventors
- 👤 Ian Coulson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 22:00
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/137; G02F1/139; G02F1/141; C; C09; C09K; C09K19/00; C09K19/04; C09K19/06; C09K19/08; C09K19/10; C09K19/12; C09K19/126; C09K19/20; C09K19/2007; C09K19/2021; G02F1/133; G02F1/1333; G02F1/1337; G02F1/133734; G02F1/133746
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
125 words
A liquid crystal device comprising: two cell walls spaced apart by a spacer; a layer of a ferro electric smectic liquid crystal material contained between the walls, said liquid crystal material having a cholesteric phase at a temperature above ambient between the smectic and isotropic phases; electrode structures on the inner facing surfaces of the cell walls; a surface alignment coating on the inner facing surface of the walls, the alignment coating providing both an alignment direction and a surface tilt of above 5° to contacting liquid crystal material; at least one polarizer arranged with its optical axis parallel to a liquid crystal molecular alignment direction; and an amount of dichroic dye in the liquid crystal material sufficient to establish a guest-host type display device.
Claim 2
Dependent Claim
125 words
A liquid crystal device comprising: two cell walls spaced apart by a spacer; a layer of a ferro electric smectic liquid crystal material contained between the walls, said liquid crystal material having a cholesteric phase at a temperature above ambient between the smectic and isotropic phases; electrode structures on the inner facing surfaces of the cell walls; a surface alignment coating on the inner facing surface of the walls, the alignment coating providing both an alignment direction and a surface tilt of above 5° to contacting liquid crystal material; at least one polarizer arranged with its optical axis parallel to a liquid crystal molecular alignment direction; and an amount of dichroic dye in the liquid crystal material sufficient to establish a guest-host type display device.
Claim 3
Dependent Claim
17 words
The device of claim 1 wherein the liquid crystal material has the following phases: solid⃡chiral smectic⃡smectic A⃡cholesteric⃡isotropic.
Claim 4
Dependent Claim
19 words
The device of claim 1 wherein the two alignment directions of the surface alignment coatings are parallel but opposite.
Claim 5
Dependent Claim
22 words
The device of claim 1 wherein the two alignment directions of the surface alignment coatings are parallel and in the same direction.
Claim 6
Dependent Claim
16 words
The device of claim 1 wherein the surface tilt is in the range 10° to 45°.
Claim 7
Dependent Claim
23 words
The device of claim 1 wherein the liquid crystal material has a net spontaneous polarisation coefficient of greater than 0.1 nC/cm 2 .
Claim 8
Dependent Claim
23 words
The device of claim 1 wherein the liquid crystal material has a net spontaneous polarisation coefficient of greater than 1.0 nc/cm 2 .
Claim 9
Dependent Claim
25 words
The device of claim 1 wherein the liquid crystal material has a ferro electric smectic phase over an operating temperature range up to 100° C.
Claim 10
Dependent Claim
25 words
The device of claim 1 wherein the liquid crystal material has a ferro electric smectic phase over an operating temperature range up to 40° C.
Claim 11
Dependent Claim
18 words
The device of claim 1 wherein the layer of liquid crystal material is up to 15 μm thick.
Claim 12
Dependent Claim
19 words
The device of claim 1 wherein the electrodes are patterned into strip electrodes forming an x, y matrix array.
Claim 13
Dependent Claim
19 words
The device of claim 1 wherein the electrodes are patterned into strip electrodes forming an r, O matrix array.
Claim 14
Dependent Claim
15 words
The device of claim 11 and further comprising driver circuits for addressing the matrix array.
Claim 15
Dependent Claim
16 words
The device of claim 1 wherein the electrodes are patterned into segments for displaying numerical values.
Claim 16
Dependent Claim
28 words
The device of claim 1 wherein an at least partially reflecting mirror is arranged behind the device to reflect light back through the liquid crystal material and polariser.
Claim 17
Dependent Claim
10 words
The device of claim 1 further including a retarder plate.
Claim 18
Dependent Claim
120 words
A liquid crystal device comprising: two cell walls spaced apart by a spacer; a layer of a ferro electric smectic liquid crystal material contained between the walls, said liquid crystal material having a cholesteric phase at a temperature above ambient between the smectic and isotropic phases; electrode structures on the inner facing surfaces of the cell walls; a surface alignment coating on the inner facing surface of the walls, the alignment coating providing both an alignment direction and a surface tilt of above 5° to contacting liquid crystal material; at least one polariser arranged with its optical axis parallel to a liquid crystal molecular alignment direction; and a second polariser arranged so that the cell walls are between said polarisers.
Claim 19
Dependent Claim
120 words
A liquid crystal device comprising: two cell walls spaced apart by a spacer; a layer of a ferro electric smectic liquid crystal material contained between the walls, said liquid crystal material having a cholesteric phase at a temperature above ambient between the smectic and isotropic phases; electrode structures on the inner facing surfaces of the cell walls; a surface alignment coating on the inner facing surface of the walls, the alignment coating providing both an alignment direction and a surface tilt of above 5° to contacting liquid crystal material; at least one polariser arranged with its optical axis parallel to a liquid crystal molecular alignment direction; and a second polariser arranged so that the cell walls are between said polarisers.
Claim 20
Dependent Claim
16 words
The device of claim 17 wherein the two polarisers are arranged with their optical axis orthogonal.
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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) | 1994-03-04 | 1994-09-03 | 1995-03-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-03-04 | 1998-09-03 | 1999-03-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-03-04 | 2002-09-03 | 2003-03-05 | $7700.00 | Window Closed / Lapsed |