Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Frame Delay Lines Inversion

IP.com Disclosure Number: IPCOM000104892D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 59K

Publishing Venue

IBM

Related People

Kimura, Y: AUTHOR [+2]

Abstract

This article describes a kind of AC modulation method of a simple matrix LCD (Liquid Crystal Display) which displays data in gray scale by a FRC (Frame Rate Control) method. One of the conventional AC modulation methods of STN-LCD (Super Twisted Nematic LCD) is a frame inversion which changes the polarity of driving the driving voltage, frame by frame. This modulation interferes with the FRC, and on some gray level, a DC factor of driving voltage deteriorates the LC (Liquid Crystal) itself. So, a recent STN-LCD which has gray scale display function by the FRC uses the lines conversion method as an AC modulation method. The inversion lines changes the polarity of the driving voltage every several lines, such as every 13 lines, every 17 lines, etc.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 75% of the total text.

Frame Delay Lines Inversion

      This article describes a kind of AC modulation method of a
simple matrix LCD (Liquid Crystal Display) which displays data in
gray scale by a FRC (Frame Rate Control) method.  One of the
conventional AC modulation methods of STN-LCD (Super Twisted Nematic
LCD) is a frame inversion which changes the polarity of driving the
driving voltage, frame by frame.  This modulation interferes with the
FRC, and on some gray level, a DC factor of driving voltage
deteriorates the LC (Liquid Crystal) itself.  So, a recent STN-LCD
which has gray scale display function by the FRC uses the lines
conversion method as an AC modulation method.  The inversion lines
changes the polarity of the driving voltage every several lines, such
as every 13 lines, every 17 lines, etc.  And the position of the
polarity changed moves randomly as the frame changes in order to
avoid background nonuniformity.  (such as a moving or fixed
horizontal stripe pattern of the background.)

      When using an electromagnetically induced digitizer with the
STN-LCD, the switching noise from the LCD AC modulation disturbs the
digitizer's operation.  To reduce the LCD AC modulation noise, a
frame delay line inversion is effective.  The principle of the frame
delay line inversion is to change the polarity of the driving voltage
every several lines plus one (or some) frame.  This is a combination
of a frame inversion and a line inversion.  In this method, the
switching rate...