EP0197742A2
Expired / Lapsed
EP
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Addressing liquid crystal cells
Assignee: Nortel Networks Ltd
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Filing: 1986-04-01
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Granted: —
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Expires: 2006-04-01
Abstract
Abstract A method of addressing a matrix addressed ferroelectric liquid crystal cell is described that uses parallel entry of balanced bipolar data pulses on one set of electrodes to co-operate with serial entry of unipolar strobe pulses on the other set of electrodes. Data entry is preceded with blanking (erasing) pulses applied to the strobe lines. The polarity of the strobing and blanking pulses is periodically reversed to maintain charge balance in the long term.
Inventors
- 👤 Peter John Ayliffe
- 👤 Anthony Bernard Davey
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-28 21:25
CPC Classifications
G; G09; G09G; G09G3/00; G09G3/20; G09G3/34; G09G3/36; G09G3/3611; G09G3/3622; G09G3/3629; G09G2310/00; G09G2310/06; G09G2310/061; G09G2310/062; G09G2310/063; G09G2310/065; G09G2320/00; G09G2320/02; G09G2320/0209
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
183 words
A method of addressing a matrix-array type liquid crystal cell with a ferroelectric liquid crystal layer whose pixels are defined by the areas of overlap between the members of a first set of electrodes on one side of the liquid crystal layer and the members of a second set on the other side of the layer, characterised in that the pixels are addrressed on a line-by-line basis after erasure, that unipolar blanking pulses are applied to the members of the first set of electrodes to effect erasure, that for selective addressing of the pixels unipolar strobing pulses are applied serially to the members of the first set of electrodes while charge balanced bipolar data pulses are applied in parallel to the members of the second set, the positive going parts being synchronised with the strobe pulse for one data significance and the negative going parts being synchronised with the strobe pulse for the other data significance, and that the polarities of the strobe and blanking pulses are periodically reversed to provide charge balance for the individual members of the first set of electrodes.
Claim 2
Independent Claim
183 words
A method of addressing a matrix-array type liquid crystal cell with a ferroelectric liquid crystal layer whose pixels are defined by the areas of overlap between the members of a first set of electrodes on one side of the liquid crystal layer and the members of a second set on the other side of the layer, characterised in that the pixels are addrressed on a line-by-line basis after erasure, that unipolar blanking pulses are applied to the members of the first set of electrodes to effect erasure, that for selective addressing of the pixels unipolar strobing pulses are applied serially to the members of the first set of electrodes while charge balanced bipolar data pulses are applied in parallel to the members of the second set, the positive going parts being synchronised with the strobe pulse for one data significance and the negative going parts being synchronised with the strobe pulse for the other data significance, and that the polarities of the strobe and blanking pulses are periodically reversed to provide charge balance for the individual members of the first set of electrodes.
Claim 3
Dependent Claim
25 words
A method as claimed in claim 1, characterised in that the polarities of the strobe and blanking pulses are periodically reversed on a regular basis.
Claim 4
Dependent Claim
25 words
A method as claimed in claim 1, characterised in that the polarities of the strobe and blanking pulses are periodically reversed on a random basis.
Claim 5
Dependent Claim
28 words
A method as claimed in claim 1, 2 or 3, characterised in that a gap separates the positive and negative going portions of each balanced bipolar data pulse.
Claim 6
Independent Claim
20 words
A method as claimed in any preceding claim, characterised in that a gap always precedes or follows each data pulse.
Claim 7
Independent Claim
40 words
A method as claimed in any preceding claim, characterised in that the positive and negative going portions of each balanced bipolar data pulse are asymmetric, one part having m times the amplitude of the other and 1/m th the duration.
Claim 8
Independent Claim
75 words
A method as claimed in any one of claims I to 5, characterised in that the blanking pulses and strobing pulses are combined so that, while the strobing part of one of these combined blanking and strobing pulses is being used for data entry on one line, the same data co-operates with the blanking part of the succeeding, and partially overlapping in time, combined blanking and strobing pulse to effect blanking of a succeeding line.
Claim 9
Dependent Claim
18 words
A method as claimed in claim 7, characterised in that the succeeding line is the next succeeding line.
Claim 10
Dependent Claim
20 words
A method as claimed in claim 7, characterised in that the succeeding line is the next but one succeeding line.
References Cited (Backward Citations)
No citation records indexed.
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