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US4765720A
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Method and apparatus for driving ferroelectric liquid crystal, optical modulation device to achieve gradation
Assignee: Canon Inc
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Filing: 1987-07-21
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Granted: 1988-08-23
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Expires: 2007-07-21
Abstract
Abstract An optical modulation device comprises first electrodes and second electrodes disposed opposite to and intersecting with the signal electrodes, and an optical modulation material providing a first and a second orientation state depending on an electric field applied thereto disposed between the first electrodes and the second electrodes, a pixel being formed at each intersection of the first electrodes and the second electrodes so as to form a matrix of pixels as a whole. The optical modulation device is driven by applying an alternating address voltage signal comprising a fore pulse and a rear pulse to an addressed electrode among the first electrodes; and applying, to the second electrodes, a first voltage signal for orienting the pixels on the addressed electrode to the first orientation state in phase with the fore pulse, and a second voltage signal for providing a pixel among the pixels on the addressed electrode with a prescribed areal ratio between the first and second orientation states in the pixel depending on given gradation data; the first and second voltage signals being set to have substantially the same absolute value.
Inventors
- 👤 Tsutomu Toyono
- 👤 Shuzo Kaneko
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 23:51
CPC Classifications
G; G09; G09G; G09G3/00; G09G3/20; G09G3/34; G09G3/36; G09G3/3611; G09G3/3622; G09G3/3629; G09G3/3637; G09G2310/00; G09G2310/06; G09G2310/061; G09G2320/00; G09G2320/02; G09G2320/0209; G09G3/2007; G09G3/2011; G09G3/207
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
184 words
A driving method for an optical modulation device comprising first electrodes and second electrodes disposed opposite to and intersecting with the first electrodes, and an optical modulation material providing a first and a second orientation state depending on an electric field applied thereto disposed between the first electrodes and the second electrodes, a pixel being formed at each intersection of the first electrodes and the second electrodes so as to form a matrix of pixels as a whole; said driving method comprising: applying an alternating address voltage signal comprising a fore pulse and a rear pulse to an addressed electrode among the first electrodes; and applying, to the second electrodes, a first voltage signal for orienting the pixels on the addressed electrode to the first orientation state in phase with the fore pulse, and a second voltage signal for providing a pixel among the pixels on the addressed electrode with a prescribed areal ratio between the first and second orientation states in the pixel depending on given gradation data; the first and second voltage signals being set to have substantially the same absolute value.
Claim 2
Dependent Claim
184 words
A driving method for an optical modulation device comprising first electrodes and second electrodes disposed opposite to and intersecting with the first electrodes, and an optical modulation material providing a first and a second orientation state depending on an electric field applied thereto disposed between the first electrodes and the second electrodes, a pixel being formed at each intersection of the first electrodes and the second electrodes so as to form a matrix of pixels as a whole; said driving method comprising: applying an alternating address voltage signal comprising a fore pulse and a rear pulse to an addressed electrode among the first electrodes; and applying, to the second electrodes, a first voltage signal for orienting the pixels on the addressed electrode to the first orientation state in phase with the fore pulse, and a second voltage signal for providing a pixel among the pixels on the addressed electrode with a prescribed areal ratio between the first and second orientation states in the pixel depending on given gradation data; the first and second voltage signals being set to have substantially the same absolute value.
Claim 3
Dependent Claim
76 words
A method according to claim 1, wherein said address signal comprises the fore pulse of a voltage of one polarity with respect to a reference voltage as defined as a voltage applied to a non-addressed first electrode, the rear pulse of a voltage of the other polarity, a voltage of the same voltage as the reference voltage preceding the fore pulse, and a voltage of the same voltage as the reference voltage succeeding the rear pulse.
Claim 4
Dependent Claim
18 words
A method according to claim 1, wherein the address voltage signal is sequentially applied to the first electrodes.
Claim 5
Dependent Claim
16 words
A method according to claim 1, wherein said optical modulation material is a ferroelectric liquid crystal.
Claim 6
Dependent Claim
17 words
A method according to claim 4, wherein said ferroelectric liquid crystal is a chiral smectic liquid crystal.
Claim 7
Dependent Claim
32 words
A method according to claim 5, wherein said chiral smectic liquid crystal is disposed in a layer thin enough to release its own helical structure in the absence of an electric field.
Claim 8
Dependent Claim
184 words
An optical modulation apparatus, comprising: an optical modulation device comprising first electrodes and second electrodes disposed opposite to and intersecting with first electrodes, and an optical modulation material providing a first and a second orientation state depending on an electric field applied thereto disposed between the first electrodes and the second electrodes, a pixel being formed at each intersection of the first electrodes and the second electrodes so as to form a matrix of pixels as a whole; means for applying an alternating address voltage signal comprising a fore pulse and a rear pulse to an addressed electrode among the first electrodes; and means for applying, to the second electrodes, a first voltage signal for orienting the pixels on the addressed electrode to the first orientation state in phase with the fore pulse, and a second voltage signal for providing a pixel among the pixels on the addressed electrode with a prescribed areal ratio between the first and second orientation states in the pixel depending on given gradation data; the first and second voltage signals being set to have substantially the same absolute value.
Claim 9
Dependent Claim
184 words
An optical modulation apparatus, comprising: an optical modulation device comprising first electrodes and second electrodes disposed opposite to and intersecting with first electrodes, and an optical modulation material providing a first and a second orientation state depending on an electric field applied thereto disposed between the first electrodes and the second electrodes, a pixel being formed at each intersection of the first electrodes and the second electrodes so as to form a matrix of pixels as a whole; means for applying an alternating address voltage signal comprising a fore pulse and a rear pulse to an addressed electrode among the first electrodes; and means for applying, to the second electrodes, a first voltage signal for orienting the pixels on the addressed electrode to the first orientation state in phase with the fore pulse, and a second voltage signal for providing a pixel among the pixels on the addressed electrode with a prescribed areal ratio between the first and second orientation states in the pixel depending on given gradation data; the first and second voltage signals being set to have substantially the same absolute value.
Claim 10
Dependent Claim
76 words
An apparatus according to claim 7, wherein said address signal comprises the fore pulse of a voltage of one polarity with respect to a reference voltage as defined as a voltage applied to a non-addressed first electrode, the rear pulse of a voltage of the other polarity, a voltage of the same voltage as the reference voltage preceding the fore pulse, and a voltage of the same voltage as the reference voltage succeeding the rear pulse.
Claim 11
Dependent Claim
18 words
An apparatus according to claim 7, wherein the address voltage signal is sequentially applied to the first electrodes.
Claim 12
Dependent Claim
16 words
An apparatus according to claim 7, wherein said optical modulation material is a ferroelectric liquid crystal.
Claim 13
Dependent Claim
17 words
An apparatus according to claim 10, wherein said ferroelectric liquid crystal is a chiral smectic liquid crystal.
Claim 14
Dependent Claim
32 words
An apparatus according to claim 11, wherein said chiral smectic liquid crystal is disposed in a layer thin enough to release its own helical structure in the absence of an electric field.
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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) | 1991-08-23 | 1992-02-22 | 1992-08-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-08-23 | 1996-02-22 | 1996-08-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-08-23 | 2000-02-22 | 2000-08-23 | $7700.00 | Window Closed / Lapsed |