Martin,

Do you intend to make a universal device that gets moved around alot?
If not, I would suggest using seven discrete photodiodes or phototransistors
for each segment mounted to allign with the center of each segment.  This
approach would require a different arrangement for any given LED readout
(size and shape) but should be much cheaper (per application) than a CCD
camera, etc as has be suggested.

Another question is how do you activate the read function?  Does a clock
announce the time at each change?  Do you push a button to get a reading?
Mark A. Corio
Rochester MicroSystems, Inc.
200 Buell Road, Suite 9
Rochester, NY  14624
Tel:  (716) 328-5850
Fax:  (716) 328-1144
e-mail:  Mcorio@aol.com

***** Designing Electronics For Research & Industry *****