US3972587A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Liquid crystal display
Assignee: BBC Brown Boveri AG Switzerland
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Filing: 1974-11-13
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Granted: 1976-08-03
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Expires: 1994-11-13
Abstract
Abstract An improved liquid crystal display apparatus is disclosed which is characterized by an especially bright and uniform readout surface. The display apparatus includes only a single polarizer placed between the light source and the liquid crystal cell, and the liquid crystal molecules are rotated through 45° about an axis normal to the surface of the liquid crystal cell.
Inventors
- 👤 Terry J. Scheffer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 20:51
CPC Classifications
B; B24; B24B; B24B9/00; B24B9/02; B24B9/06; B24B9/16; B24B9/166; G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/137; G02F1/139; G02F1/1396; G02F1/133; G02F1/1333; G02F1/1335; G02F1/13363; G02F1/133638; G02F2203/00; G02F2203/02
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
86 words
A laminar liquid crystal cell apparatus for controlling the transmission of light from a light source comprising: a reflector; a liquid crystal cell having transparent electrodes on opposite surfaces thereof, said cell containing liquid crystal molecules helically twisted through 45° about an axis normal to said electrodes, said liquid crystal cell positioned between said light source and said reflector; a quarter-wavelength plate located between said liquid crystal cell and said reflector, and, only a single polarizer located between said light source and said liquid crystal cell.
Claim 2
Dependent Claim
86 words
A laminar liquid crystal cell apparatus for controlling the transmission of light from a light source comprising: a reflector; a liquid crystal cell having transparent electrodes on opposite surfaces thereof, said cell containing liquid crystal molecules helically twisted through 45° about an axis normal to said electrodes, said liquid crystal cell positioned between said light source and said reflector; a quarter-wavelength plate located between said liquid crystal cell and said reflector, and, only a single polarizer located between said light source and said liquid crystal cell.
Claim 3
Dependent Claim
23 words
An apparatus as in claim 1, further comprising: control means coupled to said electrodes for controlling optical characteristics of said liquid crystal cell.
Claim 4
Dependent Claim
12 words
An apparatus as in claim 1, wherein: said quarter-wavelength plate is chromatic.
Claim 5
Dependent Claim
22 words
An apparatus as in claim 1, wherein: said quarter-wavelength plate consists of a polyvinylalcohol film exhibiting a retardation of approximately 140 mμ.
Claim 6
Dependent Claim
12 words
An apparatus as in claim 1, wherein: said quarter-wavelength plate is achromatic.
Claim 7
Dependent Claim
14 words
An apparatus as in claim 5, wherein: said quarter-wavelength plate is formed of apophylite.
Claim 8
Dependent Claim
16 words
An apparatus as in claim 5, wherein: said quarter-wavelength plate comprises a stretched cellulose nitrate foil.
Claim 9
Dependent Claim
14 words
An apparatus as in claim 5, wherein: said quarter-wavelength plate has a layered structure.
Claim 10
Dependent Claim
28 words
An apparatus as in claim 1, wherein: the preferred direction of the electrode surface next to the quarter-wavelength plate and the optical axis of the latter are parallel.
Claim 11
Dependent Claim
43 words
An apparatus as in claim 1, wherein: the preferred direction of the electrode surface next to the quarter-wavelength plate and the optical axis of the latter are rotated through 45° with respect to one another about an axis normal to the quarter-wavelength plate.
Claim 12
Dependent Claim
15 words
An apparatus as in claim 1, wherein: said apparatus is fabricated predominantly of thin-film components.
Claim 13
Dependent Claim
29 words
An apparatus as in claim 11, wherein: said reflector includes a backing layer and a reflecting surface, and said reflecting surface is located in front of said backing layer.
Claim 14
Dependent Claim
19 words
An apparatus as in claim 11, further comprising: a quarter-wavelength plate located between said liquid crystal and said reflector.
Claim 15
Dependent Claim
15 words
An apparatus as in claim 13, wherein: said reflector serves as one of said electrodes.
References Cited (Backward Citations)
US3731986A
Cited
US3784280A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-08-03 | 1980-02-02 | 1980-08-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-08-03 | 1984-02-02 | 1984-08-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-08-03 | 1988-02-02 | 1988-08-03 | $7700.00 | Window Closed / Lapsed |