Browse Prior Art Database

Liquid Crystal Display Back-Light Power Control Mechanism

IP.com Disclosure Number: IPCOM000114691D
Original Publication Date: 1995-Jan-01
Included in the Prior Art Database: 2005-Mar-29
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Hasegawa, K: AUTHOR [+4]

Abstract

Disclosed is a mechanism for reducing power consumption without usability degradation. This mechanism is to control the Liquid Crystal Display (LCD) back light, and is implemented by the circuit which allows to control the both of Back light intensity and power consumption with precise resolution.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 99% of the total text.

Liquid Crystal Display Back-Light Power Control Mechanism

      Disclosed is a mechanism for reducing power consumption without
usability degradation.  This mechanism is to control the Liquid
Crystal Display (LCD) back light, and is implemented by the circuit
which allows to control the both of Back light intensity and power
consumption with precise resolution.

      The Figure is the schematic circuit to allow these functions
with the minimum number of components.  LCD back light on/off is
performed by Switching transistor T1 of which on/off duration is
controlled by two kind of counters, one is On-Counter(C1) and the
other is Set-Counter(C2).  C1 counts down from the initial value and
drives T1 ON until count zero.  C1's initial value is set by software
through On-Counter Initialize register.  C2 counts down from the
initial value and cut off T1 until count zero.  C2's initial value is
set by software through Set-Counter Initialize Register.
On-Counter's count down starts at zero count of Set-Counter and also
Set-Counter's count down starts at zero count of On-Counter.  This
means that software can set On/Off frequency and duty of switching
transistor by setting appropriate count to both Initialize registers
for On-counter and Set-counter with the same resolution as system
clock.

      By using this circuit, System program is allowed to make the
delicate control of the back light intensity so that its power
consumption is reduced without usability deg...