It's fairly likely that the displays are multiplexed too, so the mux
frequency might be a good way of telling whether the light that's being
detected is from an LED segment or not.

Fibre optics in a frame might be the best way to get the light from the
displays to the sensors perhaps.

Cheers,
     Robin.

-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf
Of Olin Lathrop
Sent: 15 September 2009 12:31
To: Microcontroller discussion list - Public.
Subject: Re: [EE] Capturing RFID output data

> Roger, I've tried reading an LCD optically (not a camera). It's not
> easy or reliable. A lot of unwanted reflection and difficult to pick
> up individual pixels

That's only if you try to read it from a distance.  I believe the OP
said
LED originally, which should be easier.

Presumably the size and mechanical layout around the display are known.
The
reader device could be stuck right on the front of the display if it
then
has a display of its own.  That way it will be OK to obscure the
original
display.  Once you can detect which segments are lit, interpreting that
into
digits is easy.


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