US4824216A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Device for the modulation of the illuminating light of an electro-optic display screen
Assignee: Thales SA
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Filing: 1987-04-20
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Granted: 1989-04-25
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Expires: 2007-04-20
Abstract
Abstract The device of the invention comprises mainly a liquid crystal screen illuminated by a light source. An electrically controlled modulating device is placed between the source and the screen. Depending on the desired illuminating intensity, the electrical signal will be adapted to the modulating device. The modulating device may comprise essentially a liquid crystal cell.
Inventors
- 👤 Jean N. Perbet
- 👤 Michel Hareng
- 👤 Bruno Mourey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 18:18
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/1333; G02F1/1335; G02F1/1336; G02F1/133602; G02F1/1347; G02F1/13475; G02F1/133524
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
79 words
An illuminated electro-optic display device comprising: a light source for illuminating said electro-optic display device electrically controlled means for modulating said light source which is located between said light source and said electro-optic display device; a voltage generator connected to said electrically controlled modulating means for supplying a control voltage thereto; and an ambient light detection circuit for detecting ambient light intensity and coupled to said voltage generator for controlling said voltage generator responsive to said detected ambient light.
Claim 2
Dependent Claim
79 words
An illuminated electro-optic display device comprising: a light source for illuminating said electro-optic display device electrically controlled means for modulating said light source which is located between said light source and said electro-optic display device; a voltage generator connected to said electrically controlled modulating means for supplying a control voltage thereto; and an ambient light detection circuit for detecting ambient light intensity and coupled to said voltage generator for controlling said voltage generator responsive to said detected ambient light.
Claim 3
Dependent Claim
22 words
A device according to claim 1, wherein said electro-optic display device comprises: a twisted nematic liquid crystal containing a dichroic coloring agent.
Claim 4
Dependent Claim
18 words
A device according to claim 2, wherein the liquid crystal cell is attached to the electro-optic display unit.
Claim 5
Dependent Claim
50 words
A device for the illumination of an electro-optic display device according to claim 3, wherein: the electro-optic display unit comprises a twisted nematic liquid crystal, the unit comprising the electro-optic display unit and the liquid crystal is placed between a first polarizer and a second polarizer with orthogonal polarizing directions.
Claim 6
Dependent Claim
52 words
A device according to claim 1, further comprising: between the detection circuit and the generator: a processing circuit that receives a detection signal from the detection circuit, processes the said detection signal and gives a control signal in exchange; a control circuit receiving the said control signal and controlling the voltage generator.
Claim 7
Dependent Claim
119 words
An illuminated electro-optic display device comprising: a light source for illuminating said electro-optic display device; a twisted nematic liquid crystal placed between said light source and said electro-optic display device and which has a negative dielectrical anisotropy such that it has two states, one transparent state and the other, a diffusion state, dependent upon an electrical field being applied thereto; means for modulating the amount of light passing through said twisted nematic liquid crystal from said light source to said electro-optic display device; and a diaphragm located between the said liquid crystal and the electro-optic display unit, this diaphragm letting through light which is perpendicular to its plane and blocking light which is oblique with respect to its plane.
Claim 8
Dependent Claim
119 words
An illuminated electro-optic display device comprising: a light source for illuminating said electro-optic display device; a twisted nematic liquid crystal placed between said light source and said electro-optic display device and which has a negative dielectrical anisotropy such that it has two states, one transparent state and the other, a diffusion state, dependent upon an electrical field being applied thereto; means for modulating the amount of light passing through said twisted nematic liquid crystal from said light source to said electro-optic display device; and a diaphragm located between the said liquid crystal and the electro-optic display unit, this diaphragm letting through light which is perpendicular to its plane and blocking light which is oblique with respect to its plane.
Claim 9
Dependent Claim
24 words
Device for the modulation of the illuminating light of an electro-optic display device according to claim 6, wherein the diaphragm comprises a filtering lattice.
Claim 10
Dependent Claim
34 words
A device, as in claim 6, further comprising: two polarizing means placed on both sides of said twisted nematic liquid crystal cell and each having a polarizing direction which is orthogonal to the other.
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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) | 1992-04-24 | 1992-10-24 | 1993-04-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-04-24 | 1996-10-24 | 1997-04-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-04-24 | 2000-10-24 | 2001-04-25 | $7700.00 | Window Closed / Lapsed |