(19)
(11) EP 0 838 802 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
29.07.1998 Bulletin 1998/31

(43) Date of publication A2:
29.04.1998 Bulletin 1998/18

(21) Application number: 97307638.3

(22) Date of filing: 29.09.1997
(51) International Patent Classification (IPC)6: G09G 3/36
(84) Designated Contracting States:
AT BE CH DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE

(30) Priority: 30.09.1996 GB 9620395

(71) Applicant: SHARP KABUSHIKI KAISHA
Osaka-shi, Osaka-fu 545 (JP)

(72) Inventors:
  • Towler, Michael John
    Botley, Oxford OX2 9AL (GB)
  • Tagawa, Akira
    Kashiwa, Chiba 277 (JP)
  • Bonnet, Paul
    Littlemore, Oxford OX4 4XX (GB)

(74) Representative: Robinson, John Stuart 
Marks & Clerk Nash Court Oxford Business Park South
Oxford OX4 2RU
Oxford OX4 2RU (GB)

   


(54) Method of and apparatus for addressing a ferroelectric liquid crystal device and a ferroelectric liquid crystal device


(57) A ferroelectric liquid crystal device, such as a display panel, has a plurality of pixels arranged as rows and columns in a passive matrix arrangement. Each pixel has a plurality of switching thresholds, for instance by having different regions (7, 8) of different thicknesses, so as to provide a plurality of grey levels. A voltage waveform is applied to each pixel for switching it to a desired grey level. A blanking pulse of a first polarity is applied to reset the pixel to a reset grey level. This is followed by a compensating pulse (20) of polarity opposite the first polarity, after which a waveform for selecting the desired grey level is provided. The effect of the compensating pulse (20) is to reduce the effect of τmin shift so as to provide a relatively wide driving window (13) to allow more reliable selection of an intermediate grey level.






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