US4385807A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Visual display device with memory and telephone exchange incorporating such a device
Assignee: Thales SA
•
Filing: 1980-09-15
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Granted: 1983-05-31
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Expires: 2000-09-15
Abstract
Abstract A display device having a memory making it possible to display information supplied by electric signals and to maintain this display when the signals have disappeared. In a smectic liquid crystal display cell the two plates enclosing the liquid crystal layer can be moved apart by a piezoelectric wedge so as to make the crystal diffusive throughout. Parts of this crystal are then made transparent by applying thereto a reorientation electric field by means of a set of electrodes. The device is intended for use more particularly in telephone exchanges having a device for the display of digital data transmitted on a telephone line.
Inventors
- 👤 Jean-Noel Perbet
- 👤 Michel Hareng
- 👤 Serge Le Berre
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 07:31
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/1333; G02F1/1339; G02F1/137
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
112 words
A display device with a memory comprising: a smectic liquid crystal layer which can assume a transparent state under the action of an electrical field; first and second plates enclosing said layer; at least one first electrode supported by the face of the first plate in contact with the liquid crystal and at least one second electrode supported by the face of the second plate in contact with the liquid crystal said electrodes subjecting part of the liquid crystal layer to an electrical reorientation field; and means for momentarily modifying the position of the first plate relative to the second in order to bring the liquid crystal into a uniform diffusive state.
Claim 2
Dependent Claim
112 words
A display device with a memory comprising: a smectic liquid crystal layer which can assume a transparent state under the action of an electrical field; first and second plates enclosing said layer; at least one first electrode supported by the face of the first plate in contact with the liquid crystal and at least one second electrode supported by the face of the second plate in contact with the liquid crystal said electrodes subjecting part of the liquid crystal layer to an electrical reorientation field; and means for momentarily modifying the position of the first plate relative to the second in order to bring the liquid crystal into a uniform diffusive state.
Claim 3
Dependent Claim
18 words
A device according to claim 1, wherein the modifying means modifies the thickness of the liquid crystal layer.
Claim 4
Dependent Claim
24 words
A device according to claim 2, wherein the modifying means making it possible to vary the moves apart the two plates surrounding said layer.
Claim 5
Dependent Claim
28 words
A device according to claim 2, wherein the modifying means comprise at least one piezoelectric wedge provided with electrodes for applying a voltage for varying the wedge thickness.
Claim 6
Dependent Claim
48 words
A device according to claim 4, further comprising a substrate supporting the first plate and the piezoelectric wedge and at least one shim placed on the piezoelectric wedge and supporting the second plate, the thickness of the piezoelectric wedge being the same as that of the first plate.
Claim 7
Dependent Claim
60 words
A device according to claim 1, wherein the first plate supports a first system of linear, parallel electrodes including the first electrode and the second plate supports a second system of linear, parallel electrodes including the second electrode, said two systems of electrodes crossing one another to define a system of display points which can be addressed in matrix manner.
Claim 8
Dependent Claim
20 words
A device according to claim 1, wherein the electrodes and plates are transparent to permit a visual display by transmission.
Claim 9
Dependent Claim
36 words
A device according to claim 1, wherein the second plate and the second electrode are transparent and the first electrode is reflecting to permit a display across the second plate by reflection to the first electrode.
References Cited (Backward Citations)
US3718382A
Cited
US4040047A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-05-30 | 1986-11-29 | 1987-05-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-05-30 | 1990-11-29 | 1991-05-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-05-30 | 1994-11-29 | 1995-05-31 | $7700.00 | Window Closed / Lapsed |