Comments
SandAndAlum t1_jecchs7 wrote
LEDs are by no means monochromatic. And most use phosphors on a blue LED, not multiple LEDs.
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/#
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.
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.
Darzanak t1_jeazu8l wrote
I think that has more to do with the type of LED bulb chosen than all LED bulbs in general. The ones in my house (warm) are just fine, and so efficient.
prozacandcoffee t1_jeb3ge5 wrote
This only helps while you're at home. It sucks to be in a school, office, or store with bad lighting, because you often can't just leave.
Darzanak t1_jeb3p7v wrote
Most of those places have fluorescents, though. That is the absolute worst lighting, in my opinion.
SuspiciousCricket654 t1_jeclyhk wrote
Agreed. My wife has to leave Target after 5 minutes because of the headache.
whatistheformat t1_jeayyi7 wrote
>Out in the world, I noticed more and more public spaces had a frigid cast and a liminal flicker.
The author does have a point there. They have been slowly transitioning our neighborhood to LED street lights. It feels out of place, as if they are turning street corners into tiny prison yards. Sure, it lights the ground, but it's essentially spot lighting, not general area lighting. So rather than making a street feel lit up, it's more like aliens trying to beam up a sample of pavement or yard every 20 feet or so.
kwman11 t1_jeba3jz wrote
Same in my neighborhood. Recently they've been switching to new LED lights with a purple hue, which although not perfect, are definitely better.
despitegirls t1_jebeace wrote
They replaced our old bulbs with LED bulbs. Initially they were okay, though cooler than I'd like. Over a few months, they slowly turned purple due to a defect. From our living room, it almost looked like we had a neon sign on our front porch. Called the city to replace them.
SandAndAlum t1_jecco60 wrote
This is because of the insane choice of blue light. Destroys your night vision so you can't see the darker parts.
throwaway21316 t1_jeb4td6 wrote
If you are used to neutral white light - you get the feeling that incandescent light is a bad light like candles. Also you can have lamps with dual white LED ( https://lightingwill.com/collections/dual-white-led-strip-lights ) so you mix it as you please or by daytime. You would wonder how much the color of sunlight changes over the day - we just don't notice.
What is annoying is the flickering of cheap LED AC converter that pulses the light and result in strange effects.
OcculusSniffed t1_jef9tyw wrote
I had an old strand of LED Christmas lights that would give me some weird vertigo feeling every time I saw them in motion. It's a delicate balance, for sure
throwaway21316 t1_jefcyr6 wrote
i have seen one that is "yellow" by using red and green led in reverse with 50Hz AC .. when you move your eyes the yellow separates into red and green dots.. bit like the rainbow effect in older dlp projectors.
phdoofus t1_jebhs5g wrote
I stopped reading when the whinging never seemed to end.
odinsfox t1_jeb29s3 wrote
what a weirdly written article...
REO_Studwagon t1_jebg2n3 wrote
Can honestly say I’ve never seen any of this with my leds. I did accidentally buy some that were too white, but that was my mistake.
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.