US4762400A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ferroelectric liquid crystal electro-optical device having half-select voltage to maximize contrast
Assignee: Seiko Instruments Inc
•
Filing: 1987-05-27
•
Granted: 1988-08-09
•
Expires: 2007-05-27
Abstract
Abstract A ferroelectric liquid crystal electro-optical device driven in time-sharing comprising; a ferroelectric liquid crystal layer having bi-stable alignment characteristics, means for converting the bi-stable alignment state to optical ON state or optical OFF state, a matrix electrode and means for driving the liquid crystal layer by applying voltages to the liquid crystal layer through the matrix electrode. A voltage sufficient to change a stable alignment state of the ferro-electric liquid crystal molecular is applied to a selected pixel, a voltage insufficient to change a stable alignment state is applied to a non-selected pixel and an AC voltage for holding a stable alignment state is applied to a half-selected pixel. A bias value, which is the ratio of the amplitude of the voltage applied to the selected pixel to the amplitude of the AC voltage applied to the half-selected pixel, is set near the maximum value of B satisfying the following formula B/(B-2)≧Vsat/Vth, wherein Vsat is the minimum value of voltage which enables to change a stable alignment state to the other state and Vth is the maximum value of voltage which enables to hold the stable alignment state.
Inventors
- 👤 Sadashi Shimoda
- 👤 Takamasa Harada
- 👤 Masaaki Taguchi
- 👤 Kokichi Ito
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 13:36
CPC Classifications
G; G09; G09G; G09G3/00; G09G3/20; G09G3/34; G09G3/36; G09G3/3611; G09G3/3622; G09G3/3629
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
187 words
A ferroelectric liquid crystal electro-optical device driven in time-sharing comprising; a ferroelectric liquid crystal layer having bi-stable alignment characteristics, means for converting the bi-stable aligment state to optical ON state or optical OFF state, a matrix electrode and means for driving the liquid crystal layer by applying voltages to the liquid crystal layer through the matrix electrode, a voltage sufficient to change a stable alignment state of the ferro-electric liquid crystal molecular being applied to a selected pixel, a voltage insufficient to change a stable alignment state being applied to a non-selected pixel, an AC voltage for holding a stable alignment state being applied to a half-selected pixel, a bias value, which is the ratio of the amplitude of said voltage applied to the selected pixel to the amplitude of said AC voltage applied to the half-selected pixel, being set near the maximum value of B satisfying the following formula B/(B-2)≧Vsat/Vth, wherein Vsat is the minimum value of voltage which enables to change a stable alignment state to the other state and Vth is the maximum value of voltage which enables to hold said stable alignment state.
Claim 2
Dependent Claim
187 words
A ferroelectric liquid crystal electro-optical device driven in time-sharing comprising; a ferroelectric liquid crystal layer having bi-stable alignment characteristics, means for converting the bi-stable aligment state to optical ON state or optical OFF state, a matrix electrode and means for driving the liquid crystal layer by applying voltages to the liquid crystal layer through the matrix electrode, a voltage sufficient to change a stable alignment state of the ferro-electric liquid crystal molecular being applied to a selected pixel, a voltage insufficient to change a stable alignment state being applied to a non-selected pixel, an AC voltage for holding a stable alignment state being applied to a half-selected pixel, a bias value, which is the ratio of the amplitude of said voltage applied to the selected pixel to the amplitude of said AC voltage applied to the half-selected pixel, being set near the maximum value of B satisfying the following formula B/(B-2)≧Vsat/Vth, wherein Vsat is the minimum value of voltage which enables to change a stable alignment state to the other state and Vth is the maximum value of voltage which enables to hold said stable alignment state.
Claim 3
Dependent Claim
31 words
A device as claimed in claim 1; wherein Vsat is defined as a value in the range of voltage corresponding to 90% to 100% transmission light intensity of the electro-optical device.
Claim 4
Dependent Claim
31 words
A device as claimed in claim 1; wherein Vth is defined as a value in the range of voltage corresponding to 0% to 10% transmission light intensity of the electro-optical device.
Claim 5
Dependent Claim
51 words
A device as claimed in claim 1; wherein Vsat is defined as a value in the range of voltage corresponding to 90% to 100% transmission light intensity of the electro-optical device and Vth is defined as a value in the range of voltage corresponding to 0% to 10% transmission light intensity.
Claim 6
Dependent Claim
37 words
A device as claimed in claim 1; wherein Vsat is defined as a voltage corresponding to 100% transmission light intensity of the electro-optical device and Vth is defined as a voltage corresponding to 0% transmission light intensity.
Claim 7
Dependent Claim
17 words
A device as claimed in claim 1; wherein the ferroelectric liquid crystal is a chiral smectic one.
Claim 8
Dependent Claim
36 words
A device as claimed in claim 1; wherein the waveform of the voltage applied to the selected pixel comprises a former half having a reverse direction voltage and a latter half having a forward direction voltage.
Claim 9
Dependent Claim
29 words
A device as claimed in claim 1; wherein one frame comprises a first scanning for writing one of ON and OFF and a second scanning for writing the other.
Claim 10
Dependent Claim
15 words
A device as claimed in claim 1; wherein the A.C. voltage has no D.C. component.
Claim 11
Dependent Claim
33 words
A device as claimed in claim 1; wherein an interface of the ferroelectric liquid crystal layer is treated with a uniaxial orientation and the other interface is treated with a random homogeneous orientation.
Claim 12
Dependent Claim
15 words
A device as claimed in claim 1; wherein the electro-optical device is a display device.
Claim 13
Dependent Claim
18 words
A device as claimed in claim 1; wherein the electro-optical device is an optical shutter for a printer.
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) | 1991-08-09 | 1992-02-08 | 1992-08-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-08-09 | 1996-02-08 | 1996-08-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-08-09 | 2000-02-08 | 2000-08-09 | $7700.00 | Window Closed / Lapsed |