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EP0261900A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Display device

Assignee: EMI Group Ltd
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Filing: 1987-09-18
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Granted: —
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Expires: 2007-09-18
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Abstract

Abstract The liquid crystal display unit 1, has a video signal receiver 2 and a store 3. Time-modulation grey-scale addressing of the ferroelectric liquid crystal pixels in a display panel 4 is provided to a store 10 which records the number of changes of state for each pixel during one picture-signal. Once the most-significent bit has been processed and is being displayed on the panel 4, the change-of-state store 10 has the net number of changes which the pixel has undergone in that picture. Controller 11 causes store 10 to output the value appropriate to that pixel and pass it to driver unit 9 to produce a compensating pulse (whether positive, negative or zero) necessary to ensure that there is no net electrical potential over the entire picture interval. The display produced by the compensating pulse is cleared immediately the first data of the next picture is input to the pixel. Assuming that the LSB of the data for a pixel already on display in panel 4, then in the next scan extractor 6 passes the next LSB to comparator 7 whose other input is connected to a pixel-state store 8. Accordingly, the new bit-value is compared with the existing state of the pixel, and comparator 7 passes on an instructing signal to pixel driver unit 9 only if the state of the pixel requires changing; in such an eventuality, the driver unit 9 issues an appropriate monopulse select voltage. Comparator 7 also passes such an instructing signal.

Inventors

  • 👤 Colin Martin Waters

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-09 21:22
CPC Classifications
H; H04; H04N; H04N3/00; H04N3/10; H04N3/12; H04N3/127

Claims Analysis

Total Claims: 11
Claim 1
Independent Claim 92 words
A display device comprising: means to receive signals representing a plurality of pictures for display; a lattice of pixels; means to address each pixel a number of times for each picture-signal, the addressing means including means to apply an uni-polar signal to the pixel in accordance with a portion of a picture-signal appropriate to that pixel; means to determine any net electrical potential value resultant from the addressing of a pixel for one picture; means to apply a correction signal to a pixel in accordance with the output from the determining means.
Claim 2
Dependent Claim 92 words
A display device comprising: means to receive signals representing a plurality of pictures for display; a lattice of pixels; means to address each pixel a number of times for each picture-signal, the addressing means including means to apply an uni-polar signal to the pixel in accordance with a portion of a picture-signal appropriate to that pixel; means to determine any net electrical potential value resultant from the addressing of a pixel for one picture; means to apply a correction signal to a pixel in accordance with the output from the determining means.
Claim 3
Dependent Claim 56 words
A display device according to Claim 1, wherein the addressing means comprises means to apply an uni-polar signal to a pixel only when there is a change in the state of the pixel, and the determining means comprises means to count the number of changes in state for a pixel during its addressing for one picture-signal.
Claim 4
Dependent Claim 36 words
A display device according to Claim 1 or 2, wherein the correction means applies, in use, a correction signal in respect of one address prior to the initiation of the subsequent address for the next picture.
Claim 5
Dependent Claim 57 words
A display device according to any one of the preceding claims, wherein the display device comprises means to store the output of the determining means appropriate to each of a number of pixels, and means to pass the stored information to the correction means to apply a correction signal, advantageously intermediate that address and the subsequent address.
Claim 6
Dependent Claim 20 words
A display device according to any one of the preceding Claims, wherein liquid crystal cells form the lattice of pixels.
Claim 7
Independent Claim 77 words
A method of operating a display device having a lattice of pixels the method comprising: addressing each pixel a number of times for each picture-signal, including applying uni-polar signal to the pixel in accordance with a portion of a picture-signal appropriate to that pixel; determining any net electrical potential value resultant from the addressing of a pixel for one picture; to applying a correction signal to a pixel in accordance with the output from the determining stage.
Claim 8
Independent Claim 77 words
A method of operating a display device having a lattice of pixels the method comprising: addressing each pixel a number of times for each picture-signal, including applying uni-polar signal to the pixel in accordance with a portion of a picture-signal appropriate to that pixel; determining any net electrical potential value resultant from the addressing of a pixel for one picture; to applying a correction signal to a pixel in accordance with the output from the determining stage.
Claim 9
Dependent Claim 43 words
A method according to Claim 6, comprising applying an uni-polar signal to a pixel only when there is a change in the state of the pixel, and counting the number of changes in state for a pixel during its addressing for one picture-signal.
Claim 10
Dependent Claim 79 words
A method according to Claim 6 or 7, comprising applying a correction signal in respect of one address prior to the initiation of the subsequent address for the next picture. A method according to any one of Claims 5 to 7, comprising storing the output of the determining stage appropriate to each of a number of pixels, and passing the stored information to the correction stage to apply a correction signal, advantageously intermediate that address and the subsequent address.
Claim 11
Independent Claim 20 words
A method according to any one of Claims 6 to 8, wherein liquid crystal cells form the lattice of pixels.

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