I'm guessing the multiplexing or lack thereof is only one
concern. Are we talking about a simple reflective LCD here,
or an active-matrix backlit type (like most monitors or notebook
displays). If the latter - then given the way most barcode scanners
work (i.e., scan a light beam, often a low-power laser, across the
barcode and watch for variations in the reflected light), I think this
may be a pretty hit-or-miss proposition. There's no reason to
think that the LCD is going to reflect significantly more of the
light in those areas that appear lit up to the eye than it will in
the "dark" areas.
Even in the case of the simple reflective LCD, the basic effect
utilized by the display is often strongly wavelength-dependent -
it's still not a sure thing. Can't say more since I've never tried
---
Since the active-matrix backlit types are, I believe, universally
muxed, they'll be automatically ruled out. What'll be left then, will
be transmissive, transflective, and reflective dot matrix and
character based displays. All dot matrix will then go away, since
they're muxed, and so will all of the muxed character based displays,
so we'll be left with statically driven transmissive, transflective,
and reflective character based displays. Of the three, the
transmissive types contain no reflector, so we'll be left with
transflective and reflective displays. transflective can be either
backlit or depend on external light, or both, for the source of
illumination, and reflective depends on external light. Of the two,
the reflective will give a better contrast ratio and will therefore be
more likely to work properly as a target for a scanner.
As far as wavelength dependency goes, I just illuminated a reflective
display with red light in an otherwise totally dark room and the
contrast between light and dark segments was excellent, so I don't
expect a scanner with a red laser diode would have much trouble
differentiating between the light and dark ares of the bar code
either.
I've fooled around with using LCD's for optical attenuators and there
are no color problems until you get down to IR, and then the rules
change.