Re: [CAD_CAM_EDM_DRO] edge lighting plexi

Randy Gordon-Gilmore wrote:

> At 06:00 AM 11/28/01 +0000, Jon Elson wrote:
>
> >something that looks like standard Plexiglas and paint it translucent
> >white, and then paint over that with black paint, masking it where they
>
> Jon, from what I've seen in backlighted displays I've disassembled, it's
> more like etching/frosting the surface than a coating. You want to "leak"
> light out of the surface. Painting the surface will still leave the smooth
> acrylic surface (totally reflecting at any decent incidence angle)
> underneath.

Ahh, I thought it might be something like that. one thing we do at work is
to sand the Plexi with fine sandpaper, and then paint over it with white
paint.

I will have to try some experiments with it like that. A guy I visited to see

his laser cutter rig was making instrument panels for aircraft. He'd cut a
mask in black PVC material, then cut a similar pattern with larger holes
in real thin Plexi, about .060". The mask would cover the edge of the
Plexi with an overhang, so the pilot couldn't see the edge of the Plexi.
there were bulbs hidden in the plexi at strategic points. the whole thing
was aligned and glued over the instrument panel. There was no special
finishing of this material, it was left shiny as from the manufacturer, except

where the laser had cut the edge, which was also pretty clean. It worked
well, but wasn't supposed to be a diffuse emitter, so i guess that is a
different setup than the 'back-lighted' instrument panels.

Jon