EP0137726A2
Expired / Lapsed
EP
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Addressing liquid crystal displays
Assignee: Nortel Networks Ltd
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Filing: 1984-09-07
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Granted: —
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Expires: 2004-09-07
Abstract
Abstract A matrix array type liquid crystal device whose liquid crystal layer is ferro-electric is addressed using strobing pulses applied serially to the members of a set of electrodes on one side of the layer while balanced bipolar data pulses are applied in parallel to the members of a set of electrodes on the other side. The data pulses are twice the length of the strobing pulses. This provides a way of minimising the exposure of the pixels to 'wrong' voltages between consecutive addressings that would tend to drive them to their opposite states.
Inventors
- 👤 Peter John Ayliffe
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 19:19
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
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
116 words
A method of addressing a matrix array type liquid crystal display device with a ferro-electric liquid crystal layer whose pixels are defined by the areas of overlay between the members of a first set of electrodes on one side of the liquid crystal layer and the members of a second set of electrodes on the other side of the layer, characterised in that strobing pulses are applied serially to the members of the first set while data pulses are applied in parallel to the second set in order to address the cell line by line, and wherein the waveform of a data pulse is balanced bipolar and at least twice the duration of a strobing pulse.
Claim 2
Independent Claim
116 words
A method of addressing a matrix array type liquid crystal display device with a ferro-electric liquid crystal layer whose pixels are defined by the areas of overlay between the members of a first set of electrodes on one side of the liquid crystal layer and the members of a second set of electrodes on the other side of the layer, characterised in that strobing pulses are applied serially to the members of the first set while data pulses are applied in parallel to the second set in order to address the cell line by line, and wherein the waveform of a data pulse is balanced bipolar and at least twice the duration of a strobing pulse.
Claim 3
Dependent Claim
23 words
A method as claimed in claim 1, characterised in that the duration of a data pulse is twice that of a strobing pulse.
Claim 4
Dependent Claim
75 words
A method as claimed in claim 1 or 2, characterised in that a bipolar data pulse is positive going in the first half of the pulse duration and negative going in the second half, or is negative going in the first half and positive going in the second half, and wherein the strobing pulses are unidirectional and always synchronised with the first halves of the data pulses or alternatively always synchronised with the second halves.
Claim 5
Dependent Claim
104 words
A method as claimed in claim 3, characterised in that prior to the addressing of the pixels associated with any particular member of the first set of electrodes these pixels are all erased by a blanking pulse applied to that member of the first set of electrodes, which blanking pulse is of opposite polarity to that of the strobing pulses and is applied at or after the commencement of the bipolar data pulses used to address the pixels associated with the member of the first set of electrodes to which the strobing pulse is applied immediately preceding its application to that said particular member.
Claim 6
Dependent Claim
21 words
A method as claimed in claim 1 or 2, characterised in that the waveform of a strobing pulse is balanced bipolar.
Claim 7
Dependent Claim
70 words
A method as claimed in claim 5, characterised in that the waveform of a data pulse exhibits one polarity in the first and fourth quarters of its duration and the opposite polarity in the second and third quarters, and wherein the waveform of a strobing pulse is synchronised with the second and third quarters and exhibits one polarity in the second quarter and the opposite polarity in the third quarter.
Claim 8
Dependent Claim
65 words
A method as claimed in claim 5, characterised in that the waveform of a data pulse exhibits one polarity in the first half of its duration and the opposite polarity in the second half, wherein the waveform of a strobing pulse is synchronised with the second half and exhibits one polarity in the first half of its duration and the opposite polarity in the second.
Claim 9
Dependent Claim
65 words
A method as claimed in claim 5, characterised in that the waveform of a data pulse exhibits one polarity in the first half of its duration and the opposite polarity in the second half, wherein the waveform of a strobing pulse is synchronised with the first half and exhibits one polarity in the first half of its duration and the opposite polarity in the second.
References Cited (Backward Citations)
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