Browse Prior Art Database

Black/White Drive Method for Thin Film Transistor-Liquid Crystal Display at Power-Off

IP.com Disclosure Number: IPCOM000118217D
Original Publication Date: 1996-Nov-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 4 page(s) / 68K

Publishing Venue

IBM

Related People

Itoh, H: AUTHOR

Abstract

Disclosed is a method for 'Black/White Drive method for Thin Film Transistor-Liquid Crystal Display (TFT-LCD) using Normally-white-array-cell at Power-off of PC-System'. This method consists of the following two steps: 1. Drive TFT LCD with Black color to prevent a Light leak from Backlight. 2. Drive TFT LCD with White color to prevent a visible retention image, that is caused by non-uniformity of TFT's retention characteristics during discharging period, at Power-off.

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Black/White Drive Method for Thin Film Transistor-Liquid Crystal
Display at Power-Off

      Disclosed is a method for 'Black/White Drive method
for Thin Film Transistor-Liquid Crystal Display (TFT-LCD) using
Normally-white-array-cell at Power-off of PC-System'.  This method
consists of the following two steps:
  1.  Drive TFT LCD with Black color to prevent a Light leak
       from Backlight.
  2.  Drive TFT LCD with White color to prevent a visible
       retention image, that is caused by non-uniformity of
       TFT's retention characteristics during discharging
       period, at Power-off.

      In these days, high aperture ratio and low reflective black
matrix cause the visible retention image that is produced by the
non-uniformity of the normally-white-array-cell TFT's retention
characteristics during discharging period.

      Fig. 1 shows the relationship of Video signals and 5V of this
method.  Referring to the upper portion of Fig. 1, in the case of the
current PC-system using TFT-LCD, Video signals supplied by the
PC-system are turned off, 100mS before 5V supplied by PC-system is
turned off.

      Fig. 2 shows an Array-cell structure, data-line(= source-line),
gate-line, Vcommon-line(=Volt of common-line), Vscreen(=Volt of
screen) of TFT-LCD.

      Referring to the lower portion of Fig. 1, during this 100mS,
the following two steps are taken:
  1.  Counter-Driving with Black-color for four frames
      ...