29 Aug
2008
29 Aug
'08
10:10 a.m.
This idea was discussed on the list sometime ago, and
I did a quick experiment
with some plexiglass, forming the digits with a sequence of 'dots' formed by
the end of a drill bit in the plexiglass, and white LEDs, but it was only
moderately successful. I think I was using too-thick plexiglass, and also
concluded that one would need several LEDs per digit, making it quite
expensive, but this was a couple of years ago and white LED's were pricey.
IIRC, the light dispersion of LEDs was part of the problem (that is, they don't
disperse enough compared to incandescents).
Trying to get all the LEDs arrayed around the plexiglass edges with appropriate
light shielding may become an issue. Arrays of bare LED die would be nice..
Electroluminescent wire would do for the illumination Just lay a short
piece on the edge and tape it on with silver tape.
Switching the wire off and on might be more difficult due to the
voltage and frequency (100-200V, 60 to 2000Hz.)
You could also glue a piece of high loss light pipe used for
illumination onto the edge and end light it with LEDs. This would
provide a more even illumination.
This is a technique I have been experimenting with for signage.
--
Paxton Hoag
Astoria, OR
USA