Re: floure-sense

[rlrylander@xxxxxxx]

Sam wrote:

>  There's supposed to be a new ultra bright LED
> out on the market, which I may experiment with. The attraction here is that
> you would have a very shallow light box and control the brightness by
> merely turning off/on the appropriate LEDs to coincide with the required
> level.
> 3d Hacker's Camera Site: www.cadvision.com/3dhacker/index.htm

I've played with these white LEDs - they have a lot of nice characteristics,
but produce very directional light (hard to diffuse properly to get even
backlighting).  There are two approaches: a pair of Blue-emitting and
Yellow-emitting chips are packaged together in a single T-1 3/4 case and wired
in series (guarantees that the same current flows through both chips to
maintain color balance at different drive levels - also makes it a simple
two-terminal device) [these are sold by All Electronics Corp. www.allcorp.com],
the other approach uses a single Blue-emitting chip with phosphors incorporated
in the T-1 3/4 encasing epoxy to convert part of the Blue light to Red and
Green (the net color should again be fairly independent of drive level) [these
are made by Nichia and are available through Jameco Electronics
www.jameco.com].  It's easy to make a driver with continuously adjustable
current rather than turning off some of the LEDs to control output (you
wouldn't have to worry about changing the light distribution then).  Maybe a
light pipe like those used in the Cabin and Visual Plus flat viewers would work
well to give you a uniform distribution in a backlight.

Richard Rylander