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Browse Prior Art Database

New Driving Method of Liquid Crystal Display Device

IP.com Disclosure Number: IPCOM000117829D
Original Publication Date: 1996-Jun-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Kimura, S: AUTHOR [+3]

Abstract

Disclosed is a driving method of Liquid Crystal Display device addressed by Thin Film Transistors (TFT/LCD), which makes it possible to compensate feedthrough voltage and to control effective voltage of the liquid crystal layer through the storage capacitance electrode. This driving method also enables the compensation of the deviation of display transmittance due to the variation of liquid crystal cell thickness by applying the compensation voltage on the storage capacitance line.

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This is the abbreviated version, containing approximately 81% of the total text.

New Driving Method of Liquid Crystal Display Device

      Disclosed is a driving method of Liquid Crystal Display device
addressed by Thin Film Transistors (TFT/LCD), which makes it possible
to compensate feedthrough voltage and to control effective voltage of
the liquid crystal layer through the storage capacitance electrode.
This driving method also enables the compensation of the deviation of
display transmittance due to the variation of liquid crystal cell
thickness by applying the compensation voltage on the storage
capacitance line.

      This method is applied both for storage capacitor on gate
structure "Cs on Gate" and separate storage capacitor structure.

      Fig. 1 shows the equivalent circuit model for pixel of "Cs on
Gate" TFT/LCD array.  Fig. 2 shows the driving waveform of horizontal
line inversion and alternation common drive.

The driving condition is as follows:
  1.  The center voltage of Vc1 and Vc2 is satisfied by the following
       equation to compensate feedthrough voltage.
        (Vc1+Vc2)/2=VgmC+(VgmC-VgH)*Cgs/Cs
        (VsigC=VcomC)
  2.  The amplitude of Vc1 and Vc2 is adjusted to control the
effective
       value of the liquid crystal layer.
         Vlc =VsigA+VcomA-(Cgs+Cs)/Call*VgmA+(Vc2-Vc1)*Cs/Call/2
         Vlc'=Vlc-2*Cds/Call*(VcomA+VsigA)
         Vlceff=sqrt((Vlc[2+Vlc'[2)/2)
         (Call=Cs+Cgs+Cls+Cds)

      When the cell gap becomes thicker, hig...