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US5047757A
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Method of addressing a ferroelectric liquid crystal display
Assignee: Nortel Networks Ltd
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Filing: 1988-09-02
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Granted: 1991-09-10
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Expires: 2008-09-02
Abstract
Abstract A method is disclosed for addressing a matrix-array type liquid crystal layer. The cell has a plurality of pixels which are defined by regions of overlap between two sets of electrodes which sandwich a liquid crystal layer, each pixel having two states. The response time for switching between the two states is dependent upon the voltage across the liquid crystal layer, with a minimum occurring at a particular voltage. The method includes applying a strobe waveform to a selected member of a first set of the electrodes while a data waveform is applied to each member of the second set of electrodes. A waveform for switching a pixel defined by the selected member comprises a switching pulse of a given voltage magnitude and given duration. A waveform for not switching a pixel defined by the selected member comprises a non-switching pulse of a voltage magnitude greater than the given voltage magnitude of the switching pulse and a duration less than the given duration of the switching pulse.
Inventors
- 👤 Matthew F. Bone
- 👤 Ian Coulson
- 👤 Johnathan R. Hughes
- 👤 Peter W. Ross
- 👤 Frances C. Saunders
- 👤 Paul W. H. Surguy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 14:13
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G09; G09G; G09G3/00; G09G3/20; G09G3/34; G09G3/36; G09G3/3611; G09G3/3622; G09G3/3629; G09G2310/00; G09G2310/06
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
243 words
A method of addressing a matrix-array type liquid crystal cell with a ferroelectric liquid crystal layer having a plurality of pixels defined by areas of overlap between members of a first set of electrodes on one side of the liquid crystal layer and members of a second set of electrodes on the other side of the liquid crystal layer, each of said pixels having a first and second state and a response time for switching between said first and second state which depends on the voltage across the liquid crystal layer, said response time showing a minimum at a particular voltage; the method including the step of applying a strobe waveform to a selected member of said first set of electrodes, which strobe waveform comprises a strobe pulse of voltage magnitude V s , while a data waveform is applied to each member of said second set of electrodes, said data waveform being charge-balanced and bipolar and comprising data pulses of voltage magnitude V D , wherein a waveform for switching a pixel defined by said selected member comprises a switching pulse of voltage magnitude, (V s -V D ), and given duration, and a waveform for not switching a pixel defined by said selected member comprises a non-switching pulse of voltage magnitude, (V s +V D ), which magnitude is greater than said given voltage magnitude of said switching pulse and a duration less than said given duration of said switching pulse.
Claim 2
Independent Claim
243 words
A method of addressing a matrix-array type liquid crystal cell with a ferroelectric liquid crystal layer having a plurality of pixels defined by areas of overlap between members of a first set of electrodes on one side of the liquid crystal layer and members of a second set of electrodes on the other side of the liquid crystal layer, each of said pixels having a first and second state and a response time for switching between said first and second state which depends on the voltage across the liquid crystal layer, said response time showing a minimum at a particular voltage; the method including the step of applying a strobe waveform to a selected member of said first set of electrodes, which strobe waveform comprises a strobe pulse of voltage magnitude V s , while a data waveform is applied to each member of said second set of electrodes, said data waveform being charge-balanced and bipolar and comprising data pulses of voltage magnitude V D , wherein a waveform for switching a pixel defined by said selected member comprises a switching pulse of voltage magnitude, (V s -V D ), and given duration, and a waveform for not switching a pixel defined by said selected member comprises a non-switching pulse of voltage magnitude, (V s +V D ), which magnitude is greater than said given voltage magnitude of said switching pulse and a duration less than said given duration of said switching pulse.
Claim 3
Dependent Claim
12 words
A method according to claim 1 wherein said strobe waveform is unipolar.
Claim 4
Dependent Claim
31 words
A method according to claim 2 wherein said switching pulse comprises said component of voltage magnitude (V S -V D ) preceded by another component of voltage magnitude V D .
Claim 5
Dependent Claim
29 words
A method according to claim 2 wherein said non-switching pulse of voltage magnitude (V S +V D ) is preceded by a pulse of voltage magnitude V D .
Claim 6
Dependent Claim
17 words
A method according to claim 2, wherein the polarity of the unipolar strobe waveform is periodically changed.
Claim 7
Dependent Claim
37 words
A method according to claim 1 said data waveform having a fundamental frequency, wherein an A.C. waveform is superimposed on the waveform applied to said pixels, said A.C. waveform having a frequency greater than said fundamental frequency.
Claim 8
Dependent Claim
35 words
A method according to claim 1 wherein V s and V D are such that (V s -V D ) is substantially matched with the voltage required to effect switching with the minimum response time.
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) | 1994-09-09 | 1995-03-11 | 1995-09-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-09-09 | 1999-03-11 | 1999-09-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-09-09 | 2003-03-11 | 2003-09-10 | $7700.00 | Window Closed / Lapsed |