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US4793693A
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Ferro-electric liquid crystal electro-optical device having a drive voltage with DC and chopping components
Assignee: Seiko Instruments Inc
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Filing: 1987-03-02
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Granted: 1988-12-27
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Expires: 2007-03-02
Abstract
Abstract A ferro-electric crystal electro-optical device which uses switching between bi-stable states of ferro-electric liquid crystal molecules. A change from one of the stable states to the other is effected by applying a selected voltage having a combination of chopping pulse to which the liquid crystal molecules are not responsive and DC pulse to which the liquid crystal molecules are responsive.
Inventors
- 👤 Sadashi Shimoda
- 👤 Takamasa Harada
- 👤 Masaaki Taguchi
- 👤 Kokichi Ito
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 15:58
CPC Classifications
G; G09; G09G; G09G3/00; G09G3/20; G09G3/34; G09G3/36; G09G3/3611; G09G3/3685; G09G3/3692; G09G3/3622; G09G3/3629; G09G3/3674; G09G3/3681; G09G2310/00; G09G2310/06
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
98 words
A ferro-electric liquid crystal electro-optical device switchable between bi-stable states of ferro-electric liquid crystal molecules, comprising: means for effecting a change from one of the stable states to the other including means for applying a selected signal having a first portion and a second portion, wherein one of the first and second portions comprises a DC pulse of one polarity effective to change the molecules from one stable state to the other, and the other of the first and second portions comprises a chopping pulse of the opposite polarity ineffective to change the stable state of the molecules.
Claim 2
Dependent Claim
98 words
A ferro-electric liquid crystal electro-optical device switchable between bi-stable states of ferro-electric liquid crystal molecules, comprising: means for effecting a change from one of the stable states to the other including means for applying a selected signal having a first portion and a second portion, wherein one of the first and second portions comprises a DC pulse of one polarity effective to change the molecules from one stable state to the other, and the other of the first and second portions comprises a chopping pulse of the opposite polarity ineffective to change the stable state of the molecules.
Claim 3
Dependent Claim
24 words
An electro-optical device as claimed in claim 1; wherein the device has a dot-matrix electrode construction comprising plural scanning electrodes and plural signal electrodes.
Claim 4
Dependent Claim
62 words
An electro-optical device as claimed in claim 2; including means for selectively applying a selected signal for effecting the change of one of the stable states of the liquid crystal molecules to the other state and a selected signal for effecting the change of the other of the stable states to the one state to display pixels on a selected scanning line.
Claim 5
Dependent Claim
29 words
An electro-optical device as claimed in claim 2; including a driver operative to change the amplitude of a nonselected signal applied to display pixels on a non-selected scanning line.
Claim 6
Dependent Claim
33 words
An electro-optical device as claimed in claim 4; including means for setting the amplitude of the non-selected signal so that the liquid crystal molecules are substantially parallel to substrates sandwiching the liquid crystal.
Claim 7
Dependent Claim
18 words
An electro-optical device as claimed in claim 5; wherein the ferro-electric liquid crystal molecules exhibit negative dielectric anisotropy.
Claim 8
Dependent Claim
30 words
An electro-optical device as claimed in claim 1; including means for applying a non-selected signal having a high frequency without DC component to display pixels on a non-selected scanning line.
Claim 9
Dependent Claim
20 words
An electro-optical device as claimed in claim 1; wherein said chopping pulse is twice the amplitude of said DC pulse.
Claim 10
Dependent Claim
26 words
An electro-optical device as claimed in claim 1; wherein each of the first and second portions of the selected signal has an approximately equal time width.
Claim 11
Dependent Claim
99 words
A ferro-electric liquid crystal electro-optical device switchable between bi-stable states of ferro-electric liquid crystal molecules, comprising:means for producing a first selected signal having a combination of a chopping pulse in a front park and a DC pulse in a rear part and for applying same to a display pixel to get one of the bi-stable states; and means for producing a second selected signal having a combination of a DC pulse in the front part and a chopping pulse in the rear part and for applying same to a display pixel to get the other of the bi-stable states.
Claim 12
Dependent Claim
99 words
A ferro-electric liquid crystal electro-optical device switchable between bi-stable states of ferro-electric liquid crystal molecules, comprising:means for producing a first selected signal having a combination of a chopping pulse in a front park and a DC pulse in a rear part and for applying same to a display pixel to get one of the bi-stable states; and means for producing a second selected signal having a combination of a DC pulse in the front part and a chopping pulse in the rear part and for applying same to a display pixel to get the other of the bi-stable states.
Claim 13
Dependent Claim
24 words
An electro-optical device as claimed in claim 10; wherein the device has a dot-matrix electrode construction comprising plural scanning electrodes and plural signal electrodes.
Claim 14
Dependent Claim
27 words
An electro-optical device as claimed in claim 10; including means for selectively applying the first and second selected signals to display pixels on a selected scanning line.
Claim 15
Dependent Claim
41 words
An electro-optical device as claimed in claim 10; wherein each of the chopping pulse and DC pulse of the first selected signal has a polarity opposite to each of the chopping pulse and the DC pulse of the second selected signal.
Claim 16
Dependent Claim
27 words
An electro-optical device as claimed in claim 10; wherein the chopping pulse of the first and second selected signals is twice the amplitude of said DC pulse.
Claim 17
Dependent Claim
27 words
an electro-optical device as claimed in claim 10; wherein said chopping pulse has a high frequency under which the ferro-electric liquid crystal molecules exhibit negative dielectric anisotropy.
Claim 18
Dependent Claim
29 words
An electro-optical device as claimed in claim 10; wherein each of the front and rear parts of the first and second selected signals has an approximately equal time width.
References Cited (Backward Citations)
US4701026A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-12-27 | 1992-06-27 | 1992-12-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-12-27 | 1996-06-27 | 1996-12-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-12-27 | 2000-06-27 | 2000-12-27 | $7700.00 | Window Closed / Lapsed |