Browse Prior Art Database

Driving Method of Digital Data Driver IC

IP.com Disclosure Number: IPCOM000112926D
Original Publication Date: 1994-Jun-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Suzuki, M: AUTHOR

Abstract

Disclosed is a driving method of a high gray scale digital driver IC for a liquid crystal display. It enables to reduce a number of input voltage levels.

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Driving Method of Digital Data Driver IC

      Disclosed is a driving method of a high gray scale digital
driver IC for a liquid crystal display.  It enables to reduce a
number of input voltage levels.

      Fig. 1 shows a driving circuit using of this method.  Each
n-level analog input voltage except V0 has 4 analog switches.  The V0
has 1 switch.  The size of 4 switches are different respectively.

For example, the resistance of each switch is as follows:
SW0 > 1k&Omega., SW1 > 20k&Omega., SW2 > 40k&Omega., SW3 >
60k&Omega..

      When the input voltage is changed from Vx to Vx+1 through
switches, the output voltage can be selected out of 4 different
voltages (Vxa-Vxc) which are between Vx and Vx+1 (Fig. 2).  Because
Vx+1 has 4 different switches.

      This method enables a 64 gray scale driver IC with only 17
input voltage levels.  The number of switches are increased in this
method.  However, the area of the chips is not increased compared
with a conventional method.  Because the conventional method requires
the same number of input voltages as the number of gray levels, but
the sizes of SW1-SW3 are small in this method.  The power consumption
of the chip is reduced by reducing the number of input voltage
levels.