Comment on lightbulbs
Fedizen@lemmy.world 3 days agoYou can’t easily use a filter to turn red light into blue. Imo if you needed to light a room for a camera or something not the human eye, red seems like it would be effective for that, but given the filter situation and the eye being best at detecting green light it doesn’t make sense to use red as the base color for indoor bulbs.
From what I read, red LEDs were most efficient at 1.8v and blue more near 4v. Maybe its trivial to do second voltage line but the filter situation is probably the limiting factor here.
Aceticon@lemmy.dbzer0.com 2 days ago
Here are the LED drop voltages for reference.
LEDs aren’t just more efficient at those voltages, those are literally the difference in voltage between one side of the LED and the other side when in operation - if you feed it less than that the LED will simply not work. (Note that these drop voltages are not actually an absolute value but rather a very steep curve relative to current, but for simplification we can treat those as absolute ON/OFF voltage values).
Also the phosphor doesn’t filter light - rather it absorbs light and re-emits it in different wavelengths, the process being such that the emitted light covers a range of wavelengths even if the input light has a single wavelength as is the case for LEDs - so it’s not at all light manipulation by filtering and mixing light sources.
That said I went looking at how phosphor is used in LEDs nowadays and judging from this they don’t use red LEDs emitters at all nowadays, only blue and UV ones, and then chose a phosphor (which can be any substance, not just Phosphorous) whose emission range is towards the desired light range.
Fedizen@lemmy.world 2 days ago
The phosphorous coating here is serving to reduce the amount of blue light as an absorptive filter. Its just also doing other stuff. Idk if there’s a proper term for what its doing in whole, but your explanation is otherwise in line with what I’ve read.
Aceticon@lemmy.dbzer0.com 2 days ago
That’s not even close to reality.
Read the material linked.
Fedizen@lemmy.world 2 days ago
Fwiw, I did read the article you linked. That’s one of the articles I looked at originally.
I’m just saying its innapropriate to say its “not a filter” because the coating is doing more than partially filtering a wavelength of light; Its a categorical error.
The coating’s primary engineering function is not a filter, so maybe its frustrating to hear it described as one but it is absolutely incorrect to say its not a filter.