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EP0322022A1
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Method of driving a passive ferro-electric liquid crystal display device and ferro-electric liquid crystal device
Assignee: Koninklijke Philips NV
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Filing: 1988-12-12
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Granted: —
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Expires: 2008-12-12
Abstract
Abstract In a method of driving a passive ferro-electric display device the selection voltages, "blanking" voltages and data voltages are given a bipolar character so that the values of the data voltages with respect to the "blanking" voltage can be chosen to be so low that there is substantially no crosstalk. In a passive display device this provides the possibility of driving large numbers of lines (for example, for LCD-TV) while maintaining the contrast.
Inventors
- 👤 Wilbert Jozef Antoon Marie Hartmann
- 👤 Karel Elbert Kuijk
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 13:34
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; H; H04; H04N; H04N3/00; H04N3/10; H04N3/12; H04N3/127; G09; G09G; G09G3/00; G09G3/20; G09G3/34; G09G3/36; G09G3/3611; G09G3/3622; G09G3/3629; G09G2310/00; G09G2310/06; G09G2310/061; G09G2320/00; G09G2320/02; G09G2320/0209; G09G3/2007; G09G3/2011; G09G3/2014
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
142 words
A method of driving a display device comprising a ferro-electric liquid crystalline medium between two supporting plates, the first plate comprising a system of row electrodes and the second plate comprising a system of column electrodes defining display elements at the area of the crossings of row and column electrodes, said display elements reaching a desired transmission state from an extreme transmission state during selection, characterized in that during selection the display elements reach the desired transmission state from the extreme transmission state via drive voltages on the row electrodes and data voltages on the column electrodes, which drive voltages and data voltages are bipolar, said desired transmission state being reached dependent on the data voltages which are substantially simultaneously presented with a bipolar selection signal which is presented to the row electrode at least for a part of a line period.
Claim 2
Independent Claim
142 words
A method of driving a display device comprising a ferro-electric liquid crystalline medium between two supporting plates, the first plate comprising a system of row electrodes and the second plate comprising a system of column electrodes defining display elements at the area of the crossings of row and column electrodes, said display elements reaching a desired transmission state from an extreme transmission state during selection, characterized in that during selection the display elements reach the desired transmission state from the extreme transmission state via drive voltages on the row electrodes and data voltages on the column electrodes, which drive voltages and data voltages are bipolar, said desired transmission state being reached dependent on the data voltages which are substantially simultaneously presented with a bipolar selection signal which is presented to the row electrode at least for a part of a line period.
Claim 3
Dependent Claim
48 words
A method as claimed in Claim 1, characterized in that prior to the bipolar selection signal on a row electrode a bipolar auxiliary signal is presented which has such a duration and height of each of the sub-signals that the display element is brought to an extreme state.
Claim 4
Dependent Claim
23 words
A method as claimed in Claim 1 or 2, characterized in that the average voltage across a display element is substantially zero Volt.
Claim 5
Dependent Claim
25 words
A method as claimed in Claim 2 or 3, characterized in that the auxiliary signal and the selection signal are presented within one line period.
Claim 6
Dependent Claim
112 words
A method as claimed in Claim 4, characterized in that for a given line period which is at least four times the switching period of the ferro-electric liquid crystalline medium, data voltages are presented which have a maximum value covering at least half the voltage range within which the transition from one extreme electro-optical state to another extreme electro-optical state is effected in the transmission-voltage characteristic associated with a quarter of the line period, whilst the absolute value of the parts of the auxiliary signal is at least equal to the sum of the absolute value of the maximum data signal and the absolute value of the parts of the selection signal.
Claim 7
Dependent Claim
33 words
A method as claimed in Claim 2 or 3, characterized in that the auxiliary signal is presented during at least one line period prior to the line period in which selection takes place.
Claim 8
Dependent Claim
29 words
A method as claimed in Claim 6, characterized in that the auxiliary signal is presented during the line period prior to the line period in which selection takes place.
Claim 9
Dependent Claim
120 words
A method as claimed in Claim 7, characterized in that for a given line period which is at least twice the switching period of the ferro-electric liquid crystalline medium, data voltages are presented which have a maximum value covering at least half the voltage range within which the transition from one extreme electro-optical state to another extreme electro-optical state is effected in the transmission-voltage characteristic associated with the line period, whilst the difference between the absolute value of the parts of the auxiliary signal and the absolute value of the maximum data voltage is at least equal to the sum of the absolute value of the maximum data voltage and the absolute value of the parts of the selection signal.
Claim 10
Independent Claim
34 words
A method as claimed in any one of Claims 4 to 8, characterized in that the last part of the auxiliary signal and the first part of the selection signal have an identical sign.
Claim 11
Dependent Claim
28 words
A method as claimed in Claim 9, characterized in that the ferro-electric liquid crystalline medium is brought to the substantially non-transmissive state by means of the auxiliary signal.
References Cited (Backward Citations)
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