Combinant light or white LED light - which is better?

hotfoot

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Can you say, \"Durian\"?
I guess I should be a wee bit more specific when I mention Luxeons too - I meant them *without* their collimators. When used without optics, the LS emitters have the broadest spread I've yet seen from any LED (but I haven't seen all that many). So, a long throw may not even be necessary for blending to occur. Things could be helped along with some sort of diffusing element, like writeright, 3M magic tape..etc.

Playing around with the Techass Raven2 and some tri-color hi-flux edgelights that I have, I notice that you get colorful fringes when the outputs are (roughly) combined. Then again, these are 5mm-based, and for most 5mm-type packages, the built-in epoxy normally brings out the worst in colored LEDs, like their die pattern...etc. Their narrow beam pattern helps them not either.

I mean, I should think the folks who make 3-gun video projectors would have a harder time with things like beam alignment than with a plain ol' LED beams...
 

McGizmo

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Hotfoot,
I made a 9star with a roe of 3 red, 3 green and 3 blue I used Nichia 320's on the blue and green because of their even and wide beam. I picked the brightest Toshiba red that had a slightly narrower beam. I had each series coupled with a resistor appropriate for a 12 VDC input and I put 10k pots on each color circuit. I used POC LSD film to mic the color through diffusion. I had basically the same idea you are working on.

The red wasn't bright enough to compete with the Nichias. By backing off the blue and green a bit I could get a white light and of course other mixes. It was interesting but I decided to leave the RGB up to people who knew what they were doing. I think the hardest part is getting an even enough mix of light. I need to find that thing and see if a combination of difussing and then focusing with a magnifying lens will do a better job of mixing the light.
 

hotfoot

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Can you say, \"Durian\"?
Don, as usual you're one step ahead!
smile.gif


It'd be nice to see what your results were. I know that there's quite a bit of disparity in output perceived levels between different colored LEDs, especially for 3mm/5mm package dies. And red typically does the worst because of the wavelength. Which is why I've heard of the "tuning" that goes on with traffic lights so that each color is perceived with near-equal intensity - I think they just add more LEDs of the weaker colors, fewer of the stronger ones.

Now I wish I could take a better look at those big LED screens and see how they mix n match LEDs to produce white "pixels"...
 

Badbeams3

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I saw on the Photon BB that the Dance light...is it the Rave...if your not swinging it around and dancing, but hold it still...the light appears to be white.

Ken
 

hotfoot

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Can you say, \"Durian\"?
I was wondering if anyone here has tried out combining the 3 basic component colors of light - red, green, blue (RGB) - using the respectively colored LEDs. To be more specific, if anyone has tried producing white light by combining R,G and B Luxeons.

Consider this - the white LS has one of the lowest lumen outputs of all the luxeons, whereas the R, B and G *all* seem to have very high lumen values, even in current production LD versions. If you were doing a mod with 3 or more luxeons and you were gunning for max brightness and a good spectral content, would it be wiser to simply combine RGB LSs to produce white and wouldn't that yield a higher total output?

Theoretically, since there is no phosphor doping to absorb light as is the case with white LEDs, there *should* be more overall light with R,G and B LEDs than with 3 white LEDs right, right?

And since white LEDs have typically have a spike in the blue region of the spectrum, would't RGB LEDs provide a more balanced spectral content? Of course, there would need to be some tuning of the brightness to get the balance right, but at least some missing light "vitamins" would be in the mix, yes?

If this pans out well, it would be fairly easy to get predictable white light by combining RGB luxeon LEDs. This light would be brighter and consistent as well too because its easier to produce monochromatic LEDs than doping blue ones to get white.

So, whose interested in composite white LED light?
smile.gif
 

WayneM

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This always sounded like a good idea to me and is something I would like to try (although not necessarily with Luxeons)

Check out this link to Don Klipstein's site:
http://misty.com/people/don/ledrgb2w.html

A more even distribution over the visible spectrum, with efficiency of around 25 lumens per watt to boot.
 

papasan

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the problem with mixing LEDs is the different forward voltages of the different chemistries. red based LEDs generally have a lower operating voltage than blue/green based chemestries. of course, it wouldn't be too hard to put different droppign resistors on each LED.

i wonder how far the light would have to throw before the colors gelled together into a useable white color. i would think that a short throw would mean odd colors everywhere.

i do have a canon scanner that uses RGD LEDs as the light source for scanning. works very well and is alot thinner than tube light scanners.
 

lux0

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I've built many 'lamps' using RGB leds. The trick is to use PWM to vary the intensity of each colour, allowing you to produce a good whiteish light. Of course, with seperate PWM for each colour, you can produce any colour you want.
PICs are good for controllers, cheap and available.
 
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