EP0090988A1
Expired / Lapsed
EP
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Scanning liquid crystal display cells
Assignee: STC PLC
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Filing: 1983-03-18
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Granted: —
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Expires: 2003-03-18
Abstract
Abstract A curtailed drive scheme is disclosed for a matrix array liquid crystal display cell in which the field developed across each picture element is maintained for only a fraction of the time interval between consecutive addressings. This reduces the effects of differences in time constants across the display for addressing schemes in which the average time constant is short compared with this time interval between consecutive addressings.
Inventors
- 👤 William Alden Crossland
- 👤 Peter William Ross
- 👤 Peter John Ayliffe
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 17:22
CPC Classifications
G; G09; G09G; G09G3/00; G09G3/20; G09G3/34; G09G3/36; G09G3/3611; G09G3/3674; G09G3/3677; G09G3/3648; G09G2310/00; G09G2310/02; G09G2310/0243; G09G2310/0251; G09G3/2007; G09G3/2011
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
148 words
A direct current free method of operating a matrix array liquid crystal display device having a liquid crystal layer sandwiched between an electroded transparent front sheet and a rear sheet formed by or carrying a semiconductive layer provided with access circuitry by which the display is addressed on a line-by-line basis via a matrix array of semiconductor gates directly or indirectly connected with overlying matrix array of liquid crystal cell electrode pads, wherein the electrode on the front sheet is held at a substantially constant potential while each of the matrix array of electrode pads is repetitively addressed with data via its associated gate, and wherein after each addressing with data, the gate is closed for a predetermined period and then, at least once, is reopened to discharge the pad with respect to the front electrode, and reclosed, before it is refreshed by its next addressing with data.
Claim 2
Dependent Claim
148 words
A direct current free method of operating a matrix array liquid crystal display device having a liquid crystal layer sandwiched between an electroded transparent front sheet and a rear sheet formed by or carrying a semiconductive layer provided with access circuitry by which the display is addressed on a line-by-line basis via a matrix array of semiconductor gates directly or indirectly connected with overlying matrix array of liquid crystal cell electrode pads, wherein the electrode on the front sheet is held at a substantially constant potential while each of the matrix array of electrode pads is repetitively addressed with data via its associated gate, and wherein after each addressing with data, the gate is closed for a predetermined period and then, at least once, is reopened to discharge the pad with respect to the front electrode, and reclosed, before it is refreshed by its next addressing with data.
Claim 3
Dependent Claim
59 words
A method as claimed in claim 1, wherein the potential of the electrode pad of each 'ON' element is driven alternately positive and negative with respect to that of the front sheet electrode, and wherein the associated gate is repetitively opened to discharge the pad with respect to the front electrode between consecutive addressings of that pad with data.
Claim 4
Dependent Claim
57 words
A method as claimed in claim 1, wherein the potential of the electrode pad of each element does not alternate with respect to the potential of the front sheet electrode, and wherein the associated gate is opened to discharge the pad with respect to the front electrode only once between consecutive addressings of that pad with data.
Claim 5
Independent Claim
52 words
A method as claimed in any preceding claim, wherein the gate associated with each electrode pad is opened to discharge the pad with respect to the front electrode after each addressing after the lapse of a time interval less than half of the time interval between consecutive addressings of that electrode pad.
Claim 6
Dependent Claim
52 words
A method as claimed in claim 4, wherein the gate associated with each electrode pad is opened to discharge the pad with respect to the front electrode after each addressing after the lapse of a time interval less than one third of the time interval between consecutive addressings of that electrode pad.
References Cited (Backward Citations)
No citation records indexed.
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