As far as I understand, you need to be able to mix red, green and blue light to get white light and replace lightbulbs. But the earliest example I can find of white LEDs used a blue LED and a yellow (apparently the result of mixing red and green light) phosphor coating to scatter the light across the visible spectrum. Why couldn’t something similar be done with a red LED and a cyan (mixing blue and green) coating/cover to produce white light instead?
In: Engineering
The phosphor’s light doesn’t mix with the blue. The phosphor needs blue or UV light to reach its excited state and radiate white (broad spectrum) light. Ideally almost none of the actual LED’s light gets out.
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