Jinx wrote:
> I need to read a limited number of words that will appear on an
> LCD. This LCD will either be a standard 16 x 2 or a custom LCD
> with a font that's similar to a standard 16 x 2. There are four words,
> of about 8 characters each

Do the four words have significantly different numbers of active pixels?
If so, you could just using a pair of photon detectors to measure the
area covered by pixels. One sensor for the text, one over an 'always blank'
area to compensate for backlight variance (or your supplied front light) differences.
I would suggest that if the words are variable length, to mask the
text sensor to use the fewest characters to maximize the differences detected.

> I've tried a couple of experiments with photo-diodes that were a
> little bit promising, but not spectacular. Maybe the array from a
> scanner would do a better job, although that may involve some
> small transport mechanism to move the array across the LCD. But
> if that's the best solution, c'est la vie

You can also get photodiode linear arrays. Just image a line of the display
with a relay lens and you should be able to come up with enough different
values to be able to distinguish the texts. They don't need to be sharply
focused, nor perfectly aligned if you have a 'calibrate' routine to learn
the values for each text.

I see this a being easier to interface than using a full blown camera.

Robert
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist