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ddr1ver t1_jeayt9c wrote

Unlike an incandescent light bulb, which produces a continuous spectrum of light, LEDs emit light at a particular wavelength. They mix LEDs in a bulb to get a certain spectrum of light. If you don’t like the light coming out of your LED bulb, look for one with a different spectrum. Common ones come in amber, soft white, bright white, cool white, or daylight spectrum ranges.

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SandAndAlum t1_jecchs7 wrote

LEDs are by no means monochromatic. And most use phosphors on a blue LED, not multiple LEDs.

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ddr1ver t1_jecx6bk wrote

That’s not the way I learned it.

“Table 1 shows, different LEDs have different emission spectra: each with a very thin emission spectrum. LEDs only emit one color of light not because they have colored plastic over white light, but because they only emit light at a single wavelength.”

https://sites.tufts.edu/eeseniordesignhandbook/2015/leds-technology/#

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SandAndAlum t1_jed240z wrote

http://i.stack.imgur.com/6kuZf.png

Blue LEDs are much more efficient than most other colours and having three sets of voltage control or three seperate circuits is more expensive. Plus "single wavelength" is only even approximately true of a laser. Those spectra you linked to are still a fairly broad range (to the point where red and green can even be somewhat distinct under an orange LED even if both are very orange-ish).

Additionally your source describes a modern white LED

> The other method of creating white light is known as spectrum adjustment.

> Spectrum adjustment happens when light is absorbed and then re-emitted again. By doing so, the color and appearance of the light can be altered. There is a caveat, however, that the light can only be shifted to larger wavelengths. If a material were able to absorb a long wavelength of light and emit the same amount of a shorter wavelength, this would violate the conservation of energy. This is why it was not possible to generate blue light from other diodes. However, the reverse process does in fact work: if a blue diode is passed thorough a yellow phosphor, the blue and yellow combine into a white light well suited for everyday tasks.

RGB LEDs are at least three (and sometimes four) LEDs though.

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WangEnlargement t1_jeev8q2 wrote

> They mix LEDs in a bulb to get a certain spectrum of light.

No serious LED bulb manufacturer has done this for decades. The LEDs are coated with a phospher compound that converts a single wavelength to a spectrum. You can buy high CRI bulbs that are nearly indistinguishable from incandescent bulbs, but they are dimmer than standard 80 CRI bulbs.

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