US3881808A
Expired / Lapsed
US
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Liquid crystal light control device having a high transmission efficiency
Assignee: Motorola Solutions Inc
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Filing: 1973-12-07
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Granted: 1975-05-06
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Expires: 1993-12-07
Abstract
Abstract A high image transmission efficiency for a precisely controllable time duration is provided by two twisted nematic, liquid crystal cells sandwiched between two polarizers. The polarizers are cross polarized. If neither liquid crystal cell is activated, the plane of polarization of light passed by the first polarizer is rotated by the first and second cells so that the light is absorbed by the second polarizer. If only the first cell is activated, the light and image are passed through the device. If both cells are activated, the light passed by the first polarizer is absorbed by the second polarizer. Circuitry for operating the liquid crystal device and a camera including a mechanical shutter which operates in cooperation with the device are also disclosed.
Inventors
- 👤 Richard W Gurtler
- 👤 Reuben Wechsler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 15:40
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/1313; G02F1/133; G02F1/1333; G02F1/1347; G02F1/13471; G02F1/137; G02F1/139; G02F1/1396
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
127 words
A light control device including in combination: first polarizer means polarized in a predetermined direction; first twisted nematic liquid crystal cell with a first surface juxtapositioned along said first polarizer means and a second surface, said first liquid crystal cell having liquid crystal material with selectively oriented molecules interposed between said first and second surfaces thereof; second twisted nematic liquid crystal cell with a first surface juxtapositioned along said second surface of said first liquid crystal cell and a second surface, said second liquid crystal cell having liquid crystal material with selectively oriented molecules interposed between said first and second surfaces thereof; and second polarizer means juxtapositioned along said second surface of said second liquid crystal cell, said second polarizer means being polarized in another predetermined direction.
Claim 2
Dependent Claim
127 words
A light control device including in combination: first polarizer means polarized in a predetermined direction; first twisted nematic liquid crystal cell with a first surface juxtapositioned along said first polarizer means and a second surface, said first liquid crystal cell having liquid crystal material with selectively oriented molecules interposed between said first and second surfaces thereof; second twisted nematic liquid crystal cell with a first surface juxtapositioned along said second surface of said first liquid crystal cell and a second surface, said second liquid crystal cell having liquid crystal material with selectively oriented molecules interposed between said first and second surfaces thereof; and second polarizer means juxtapositioned along said second surface of said second liquid crystal cell, said second polarizer means being polarized in another predetermined direction.
Claim 3
Dependent Claim
107 words
The light control device of claim 1 wherein: said first polarizer means is polarized in a first direction; and said liquid crystal material adjacent said first surface of said first liquid crystal cell being aligned in said first direction, said liquid crystal material adjacent said second surface of said first liquid crystal cell having an unactivated alignment in a second direction, said liquid crystal material between said first and second surfaces having unactivated orientations which vary between said first and second directions, said unactivated first liquid crystal cell thereby being adapted to transmit and rotate the plane of polarization of light transmitted by said first polarizer means.
Claim 4
Dependent Claim
86 words
The light control device of claim 2 wherein: said liquid crystal material of said second liquid crystal cell is adjacent said first surface of said second liquid crystal cell being aligned in said first direction, said liquid crystal material oF said second liquid crystal cell adjacent said second surface having an unactivated alignment in said second direction, said liquid crystal material between said first and second surfaces of said second liquid crystal cell having unactivated orientations which vary between said first direction and said second direction.
Claim 5
Dependent Claim
17 words
The light control device of claim 3 wherein said second direction is perpendicular to said first direction.
Claim 6
Dependent Claim
18 words
The light control device of claim 4 wherein said second polarizer means is polarized in said second direction.
Claim 7
Dependent Claim
118 words
A light control device including in combination: normally closed mechanical shutter means located in an image path; normally closed liquid crystal shutter means located in series with said mechanical shutter means in said image path, said liquid crystal shutter means having first polarizer means polarized in a first direction, first twisted nematic liquid crystal cell means having a first surface juxtapositioned along said first polarizer means and a second surface, second twisted nematic liquid crystal cell means having a first surface juxtapositioned along said second surface, first liquid crystal cell means and a second surface, and a second polarizer means polarized in a second direction and juxtapositioned along said second surface of said second liquid crystal cell means.
Claim 8
Dependent Claim
118 words
A light control device including in combination: normally closed mechanical shutter means located in an image path; normally closed liquid crystal shutter means located in series with said mechanical shutter means in said image path, said liquid crystal shutter means having first polarizer means polarized in a first direction, first twisted nematic liquid crystal cell means having a first surface juxtapositioned along said first polarizer means and a second surface, second twisted nematic liquid crystal cell means having a first surface juxtapositioned along said second surface, first liquid crystal cell means and a second surface, and a second polarizer means polarized in a second direction and juxtapositioned along said second surface of said second liquid crystal cell means.
Claim 9
Dependent Claim
22 words
The light control device of claim 6 wherein said first and second polarizer means are cross polarized with respect to each other.
Claim 10
Dependent Claim
60 words
The light control device of claim 6 wherein: said liquid crystal material adjacent said first surface being aligned in said first predetermined direction, said liquid crystal material adjacent said second surface being aligned in said second predetermined direction, said liquid crystal material between said first and second surfaces having unactivated orientations which vary between said first and said second directions.
Claim 11
Dependent Claim
30 words
The light control device of claim 8 wherein said liquid crystal material of said first and second liquid crystal cells exhibit homeotropic alignment when activated in response to electrical signals.
Claim 12
Dependent Claim
99 words
The light control device of claim 6 further including: electrical circuit means having a first set of electrodes connected to said first liquid crystal cell means and a second set of electrodes connected to said second liquid crystal cell means; said electrical circuit means having a first circuit providing a first control voltage which activates said first liquid crystal cell to render the light control device transmissive; and said circuit means having a second circuit providing second control voltages which activates both said first liquid crystal cell and second liquid crystal cell to render the light control device non-transmissive.
Claim 13
Dependent Claim
123 words
A light control device including in combination: first polarizer means polarized in a predetermined direction; second polarizer means polarized in a second predetermined direction; and first and second liquid crystal cells positioned between said first and second polarizer means, one of said liquid crystals serving to rotate light passing through said first polarizer means to the predetermined direction of said second polarizer means when one of said liquid crystals is in an unactivated state and the other is in an activated state, thereby to pass light through said device, and said second polarizer means blocking passage of light passing through said first polarizer means and first and second liquid crystal cells when both liquid crystal cells are in an activated or unactivated state.
Claim 14
Dependent Claim
123 words
A light control device including in combination: first polarizer means polarized in a predetermined direction; second polarizer means polarized in a second predetermined direction; and first and second liquid crystal cells positioned between said first and second polarizer means, one of said liquid crystals serving to rotate light passing through said first polarizer means to the predetermined direction of said second polarizer means when one of said liquid crystals is in an unactivated state and the other is in an activated state, thereby to pass light through said device, and said second polarizer means blocking passage of light passing through said first polarizer means and first and second liquid crystal cells when both liquid crystal cells are in an activated or unactivated state.
Claim 15
Dependent Claim
39 words
A camera including, in combination: lens means located in an image suitable for transmitting an image to a light sensitive image recieiving medium; and a shutter comprising the light control device of claim 11 located in the image path.
Claim 16
Dependent Claim
15 words
The camera of claim 12 additionally comprising: a mechanical shutter located in the image path.
Claim 17
Dependent Claim
40 words
A camera including, in combination: lens meaNs located in an image path suitable for transmitting an image to a light sensitive image receiving medium; and a shutter comprising the light control device of claim 7 located in the image path.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-05-05 | 1978-11-04 | 1979-05-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-05 | 1982-11-04 | 1983-05-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-05 | 1986-11-04 | 1987-05-06 | $7700.00 | Window Closed / Lapsed |