EP0342835A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Liquid crystal cell addressing
Assignee: STC PLC
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Filing: 1989-05-08
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Granted: —
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Expires: 2009-05-08
Abstract
Abstract A colour shaded display is provided using a co-ordinate addressed ferroelectric liquid crystal display cell. Monochrome addressing of the display is performed in the normal way to produce bistable switching of the pixels. Then lower voltage pulses (41, 43, 45) are applied to blocks of pixels to produce transient changes of state at particular times synchronised with rapid changes in the colour of backlighting of this cell.
Inventors
- 👤 Peter William Ross
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 12:18
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G09; G09G; G09G3/00; G09G3/20; G09G3/34; G09G3/3406; G09G3/3413; G02F1/133; G02F1/1333; G02F1/1335; G02F1/1336; G02F1/133621; G02F1/133622; G09G2310/00; G09G2310/02; G09G2310/0237
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
175 words
A method of providing a shaded display, in which method the pixels of an illuminated liquid crystal cell exhibiting bistability of operation are selectively addressed on a repetitive basis to produce a patterning of pixels with selected pixels of the cell in a first stable state and unselected pixels in the other stable state, wherein between consecutive ones of said selective addressings the illumination conditions are changed, characterised in that while the illumination conditions are changed a chosen group of the pixels of the cell is twice re-addressed, first to induce a transition only of the selected pixels that are within the chosen group from said first stable state into a metastable state, and second to induce a transition only of the selected pixels that are within the chosen group from said metastable state back into said first stable state, whereby the selected pixels within the chosen group are provided with an appearance distinguished from that of unselected pixels within the chosen group and from both selected and unselected pixels not within the chosen group.
Claim 2
Independent Claim
175 words
A method of providing a shaded display, in which method the pixels of an illuminated liquid crystal cell exhibiting bistability of operation are selectively addressed on a repetitive basis to produce a patterning of pixels with selected pixels of the cell in a first stable state and unselected pixels in the other stable state, wherein between consecutive ones of said selective addressings the illumination conditions are changed, characterised in that while the illumination conditions are changed a chosen group of the pixels of the cell is twice re-addressed, first to induce a transition only of the selected pixels that are within the chosen group from said first stable state into a metastable state, and second to induce a transition only of the selected pixels that are within the chosen group from said metastable state back into said first stable state, whereby the selected pixels within the chosen group are provided with an appearance distinguished from that of unselected pixels within the chosen group and from both selected and unselected pixels not within the chosen group.
Claim 3
Dependent Claim
44 words
A method as claimed in claim 1 wherein the illumination conditions are changed in a manner to provide an appearance for the selected pixels within the chosen group distinguished in colour from that of both selected and unselected pixels not within said chosen group.
Claim 4
Dependent Claim
30 words
A method as claimed in claim 1 or 2 wherein the liquid crystal cell is a ferroelectric cell, and wherein bistability of operation is sustained by an applied alternating potential.
Claim 5
Dependent Claim
59 words
A method as claimed in claim 3 wherein said applied alternating potential sustaining bistability of operation is furnished at least in part by bipolar data pulses applied in parallel to a first set of electrodes which co-operate with a second set of electrodes by means of which two sets of electrodes the cell is addressed on a co-ordinate basis.
Claim 6
Dependent Claim
189 words
A liquid crystal display including a liquid crystal cell exhibiting bistability of operation, cell illumination, and means for selectively addressing pixels of the display, wherein said means includes a data store and a controller which is adapted to address a set of said pixels, with data from the data store to produce a patterning of said set of pixels with selected pixels of the set in a first stable state and unselected pixels of the set in the other stable state, the cell being arranged such that pixels in the first state have an appearance contrasting with that of pixels in the other stable state, and characterised in that the controller is adapted then to address at least one subset of said set of pixels to induce a transition of the selected pixels within that subset from the first stable state into a metastable state while the controller also regulates the illumination provided by the illumination means in a manner to provide for those selected pixels within the subset an appearance distinguished from that of both selected and unselected pixels of the set which are excluded from the subset.
Claim 7
Dependent Claim
189 words
A liquid crystal display including a liquid crystal cell exhibiting bistability of operation, cell illumination, and means for selectively addressing pixels of the display, wherein said means includes a data store and a controller which is adapted to address a set of said pixels, with data from the data store to produce a patterning of said set of pixels with selected pixels of the set in a first stable state and unselected pixels of the set in the other stable state, the cell being arranged such that pixels in the first state have an appearance contrasting with that of pixels in the other stable state, and characterised in that the controller is adapted then to address at least one subset of said set of pixels to induce a transition of the selected pixels within that subset from the first stable state into a metastable state while the controller also regulates the illumination provided by the illumination means in a manner to provide for those selected pixels within the subset an appearance distinguished from that of both selected and unselected pixels of the set which are excluded from the subset.
References Cited (Backward Citations)
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