The
Passive Matrix LCD(PMLCD) is the
simplest and
cheapest
graphic LCDs to make. The PMLCD uses a
simple grid type
adressing of each
pixel. The
buildup of a PMLCD is
similar to
other
LCDs. The two
glassplates are given
lines of
transparent electrodes made from
indium-
tinoxide.
One is given horisontal lines, the other vertical. These
rows and
columns are then
connected to the
driver/
control
electronics.
This kind of
display is
OK for two
shade monochrome displays.
They need
less power than
Active Matrix LCDs(
AMLCD), and
are therefore often
used in
graphic calculators and B/W
PDAs.
But has a slow
update rate and due to
relatively
high resistance
in the
transparent electrodes, the
accurate voltage control neaded
for
grayscale is hard. On
older,
cheaper
laptops this
LCD type
is used. It's
easy to
identify a PMLCD on a
laptop since the
slow
updates makes a ghostimage or
fading effect on
fast moving objects(like a
mouse pointer), and due to the
voltage control problem, a
change
in one
pixel may
lead to a
small but
detectable change in
intencity
of the
entire row or
coloumn. Therefore most
modern PC LCDs
uses
active matrix technology.