Quote:
Originally Posted by John F
It isn't just "changing colors though, it is (potentially) stopping the emission of blue light altogether. If only one LED is generating blue light, and it is turned off, how can blue light be transmitted?
"... In the most lowest form it is still there ..."
To anyone, is this true? So if the red LED is at 100%, and the green LED is at 100%, and the blue is at 0%, the red and green LEDs will emit some amount of blue? And in theory maybe they do, but is it even detectable by the human eye, or at an amount that is harmful?
I'm just curious to the "science" behind this. And FWIW, I'm not an LED or color expert.  |
Most red/green/blue LEDs are not only monochromatic, they have an extremely narrow bandwidth (See the attached image). There are several ways of making a white LED, one is to use red, green and blue LEDs in the same package with multiple leads, another (and more common) is to take a blue or UV LED and add phosphors* (much the same as a fluorescent light). The mix of phosphors used is what causes white LEDs to have different colour temperatures -- again similar to fluorescent lights.
*One difference is that white LEDs often use a single yellow phosphor, the light from which mixes with the blue LED light to appear white which is currently the most efficient but has lousy colour rendering. Other white LEDs use a mix of green and red phosphors to give a more continuous spectrum and a higher colour rendering index.
I've attached an image showing the bandwidth of typical RGB LEDs.