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by layer8 700 days ago
Yes, it’d be two subpixels instead of the current three. It’s not clear that that’s worth the added complexity of having to control each subpixel across two dimensions (brightness and wavelength) instead of just one (brightness).
1 comments
Retr0id 700 days ago
Can you produce "white" with just two wavelengths?
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layer8 700 days ago
Yes, mix two complementary colors like orange and cyan. You just need two wavelengths that hit all three cone types [0] in the right ratio. There’s the possibility that it’s subject to more variation across individuals though, as not everyone has exactly the same sensitivity curves.

[0] https://upload.wikimedia.org/wikipedia/commons/f/f1/1416_Col...

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exmadscientist 700 days ago
Human vision in the yellow (~590nm) region is known to be extremely sensitive to particular wavelengths. Observe how quickly things go from green through yellow to amber/orange!

So this is probably a nonstarter.

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mark-r 698 days ago
Every single white LED bulb you buy for your light fixtures is a mix of blue LED and yellow phosphor, so in practice it's no problem at all. Although I do concede that the yellow is probably not monochromatic.
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exmadscientist 698 days ago
It is 100% not monochromatic and that makes all the difference.

Here's one model I'm fairly familar with, having evaluated it for design-in to a product a few years back: https://www.lightstec.com/wp-content/uploads/2018/10/Philips... (apologies for the non-authoritative link, their entire datasheet server appears to be down....)

Take a look at page 8 (PDF page 9), Figure 4, "Relative Spectral Distribution vs. Wavelength". Look at those spectral curves and what that phosphor really does. See that nice broad peak, that's pretty insensitive to the exact details? A little shift in the peak doesn't change the output much. And yet, they still bin white LEDs intensively!

These things just do not work with monochromatic emission in the orange. And the phosphor isn't even that good at low color temperatures (CCTs). Below about 2000K-2400K (ish), this approach doesn't work: the resulting LED looks like yellow trash, not like you'd expect (it should look something like a candle flame). So even phosphors can't get you down all that far in CCT. (There are probably expensive phosphors that can do it... but none were in mass production five or six years ago when I did a deep search.)

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