Patent US4477151A successfully refreshed from Google Patents.
US4477151A
Expired / Lapsed
US
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Smectic liquid crystal cell with heat pulse and laser
Assignee: Nortel Networks Ltd
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Filing: 1981-12-28
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Granted: 1984-10-16
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Expires: 2001-12-28
Abstract
Abstract A method of operating a homeotropically aligned smectic liquid crystal cell in which the cell is turned from a clear to a scattering state by illumination with an intense flash of light after which a focused laser beam is scanned across the layer to leave clear tracks where homeotropic alignment has been restored thereby producing a display providing, in projection, bright lines on a dark background.
Inventors
- 👤 Derek H. Mash
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 15:14
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/132; Y; Y10; Y10S; Y10S359/00; Y10S359/90
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
197 words
A method of operating a liquid crystal display cell having two plates defining a space filled with a layer of liquid crystal material exhibiting a smectic phase, wherein the surfaces of said plate in contact with said layer cause the molecules of the layer adjacent said surfaces to assume a substantially visually clear state that is a substantially ordered state when said layer is taken by slow cooling into a smectic phase from a less ordered phase in the absence of an applied electric field, the method comprising the steps of: first illuminating substantially all of said layer with a flash of light from a flash source at a predetermined flux density to provide said layer with a short duration heat pulse which causes the illuminated part of said layer to enter the isotropic state and return to a smectic phase sufficiently rapidly for said layer to assume and retain a light scattering disordered molecular arrangement of molecules in the smectic phase thereby providing a more or less uniform background; and thereafter writing on said background by traversing a focused laser beam over selected portions of the flash-illuminated part of said layer to leave a visible track.
Claim 2
Independent Claim
197 words
A method of operating a liquid crystal display cell having two plates defining a space filled with a layer of liquid crystal material exhibiting a smectic phase, wherein the surfaces of said plate in contact with said layer cause the molecules of the layer adjacent said surfaces to assume a substantially visually clear state that is a substantially ordered state when said layer is taken by slow cooling into a smectic phase from a less ordered phase in the absence of an applied electric field, the method comprising the steps of: first illuminating substantially all of said layer with a flash of light from a flash source at a predetermined flux density to provide said layer with a short duration heat pulse which causes the illuminated part of said layer to enter the isotropic state and return to a smectic phase sufficiently rapidly for said layer to assume and retain a light scattering disordered molecular arrangement of molecules in the smectic phase thereby providing a more or less uniform background; and thereafter writing on said background by traversing a focused laser beam over selected portions of the flash-illuminated part of said layer to leave a visible track.
Claim 3
Dependent Claim
37 words
The method of claim 1, further comprising the additional step of placing a light-absorbing patterned mask between said flash source and said layer, the clear portion of said mask corresponding to said illuminated part of said layer.
Claim 4
Dependent Claim
21 words
A method as claimed in claim 1 wherein said liquid material of said layer absorbs the energy from said flash source.
Claim 5
Dependent Claim
34 words
A method as claimed in claim 1 wherein at least one of said plates includes an energy-absorbing coating adjacent said layer of liquid material and said coating absorbs the energy from said flash source.
Claim 6
Dependent Claim
24 words
A method as claimed in claim 3 or 4 wherein said absorbed energy density has a predetermined value of 0.1-2.0 joules-cm -2 per flash.
Claim 7
Dependent Claim
29 words
A method as claimed in claim 1, 3 or 4 wherein the beam traversal, in relation to the rate of movement and the beam power, leaves a clear track.
Claim 8
Dependent Claim
45 words
A method as claimed in claim 1, 3 or 4 wherein said liquid material of said layer includes a substance exhibiting a smectic phase to which substance has been added a quantity of dye to promote therein the absorption of radiation from the flash source.
Claim 9
Dependent Claim
31 words
A method as claimed in claim 1, 3 or 4 wherein said liquid material of said layer exhibits positive dielectric anisotropy and said visually clear state is the homeotropically aligned state.
Claim 10
Dependent Claim
184 words
A display system comprising: a display cell having two plates defining a space filled with a layer of liquid material exhibiting a smectic phase, wherein the surfaces of said plates in contact with said layer cause the molecules of said layer adjacent said surface to assume a substantially visually clear state that is a substantially ordered state when said layer is taken by slow cooling into a smectic phase from a less-ordered phase in the absence of an applied electric field, a flash source for illuminating substantially all of said layer with a flash of light at a predetermined flux density to provide said layer with a short duration heat pulse which causes the illuminated part of said layer to enter the isotropic state and return to a smectic phase sufficiently rapidly for said layer to assume and retain a light-scattering disordered molecular arrangement of molecules in the smectic phase thereby providing a more or less uniform background, and means for thereafter writing on said background by traversing a focused laser beam over selected portions thereof, thereby leaving a visible track over said background.
Claim 11
Dependent Claim
184 words
A display system comprising: a display cell having two plates defining a space filled with a layer of liquid material exhibiting a smectic phase, wherein the surfaces of said plates in contact with said layer cause the molecules of said layer adjacent said surface to assume a substantially visually clear state that is a substantially ordered state when said layer is taken by slow cooling into a smectic phase from a less-ordered phase in the absence of an applied electric field, a flash source for illuminating substantially all of said layer with a flash of light at a predetermined flux density to provide said layer with a short duration heat pulse which causes the illuminated part of said layer to enter the isotropic state and return to a smectic phase sufficiently rapidly for said layer to assume and retain a light-scattering disordered molecular arrangement of molecules in the smectic phase thereby providing a more or less uniform background, and means for thereafter writing on said background by traversing a focused laser beam over selected portions thereof, thereby leaving a visible track over said background.
Claim 12
Dependent Claim
22 words
A display system as claimed in claim 9 wherein said liquid material of said layer absorbs the energy from said flash source.
Claim 13
Dependent Claim
35 words
A display system as claimed in claim 9 wherein at least one of said plates includes an energy-absorbing coating adjacent said layer of liquid material and said coating absorbs the energy from said flash source.
Claim 14
Dependent Claim
34 words
The display system of claim 9 further comprising a light-absorbing patterned mask between said display cell and said flash source, the clear portion of said mask corresponding to said illuminated part of said layer.
Claim 15
Dependent Claim
25 words
A display system as claimed in claim 10 or 11 wherein said absorbed energy density has a predetermined value of 0.1-2.0 joules-cm -2 per flash.
Claim 16
Dependent Claim
30 words
A display system as claimed in claim 9, 10 or 11 wherein the beam traversal, in relation to the rate of movement and the beam power, leaves a clear track.
Claim 17
Dependent Claim
47 words
A display system as claimed in claim 9, 10 or 11, wherein said liquid material of said layer includes a substance exhibiting a smectic phase to which substance has been added a quantity of dye to promote therein the absorption of the radiation from the flash source.
Claim 18
Dependent Claim
32 words
A display system as claimed in claim 9, 10 or 11 wherein said liquid material of said layer exhibits positive dielectric anisotropy and said visually clear state is the homeotropically aligned state.
References Cited (Backward Citations)
US3114836A
Cited
US4040047A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-10-16 | 1988-04-16 | 1988-10-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-10-16 | 1992-04-16 | 1992-10-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-10-16 | 1996-04-16 | 1996-10-16 | $7700.00 | Window Closed / Lapsed |