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 discovery happened slightly afterwards; it wasn’t known at the time (I don’t think). We needed the blue at the time to mix with red and green (as you mention).
Slight aside, but the blue one was so important that the dude who figured it out got a Nobel.
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