Yes, RED, GREEN, BLUE. They combine to make a large array of colors, and white. As nice as that white may be for video, you may not like it for ambient light. 
And why do those 3 colors simulate the whole visible spectrum? Because those are the 3 color sensors we have in our eyes. Some parrots have 5. Imagine how fine their color vision must be!
And why do those 3 colors simulate the whole visible spectrum? Because those are the 3 color sensors we have in our eyes. Some parrots have 5. Imagine how fine their color vision must be!
Yes, RED, GREEN, BLUE. They combine to make a large array of colors, and white. As nice as that white may be for video, you may not like it for ambient light.
Exactly! It is what I meant from the beginning.
Not necessary. It can be as well an artifact of processing. As I proposed from the beginning, take full set of paints, pencils, flamasters, light them by different sources of light and see the difference. Some of them when lit by LED white light look much darker than when lit by incandescent light. That means, no matter how white are white objects lit by such light, it is incomplete.
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I have no idea which luminophore they use now, but I don't believe that they produce smooth wide spectrum similar to natural sources of light. I will check with CD under the angle this evening, it is the simplest available tool.
Wavebourn, here is another eye spectrum chart I found on the web that seems to agree with many others.
Courtesy of One Minute Astronomer
Could we say that we actually have 4 color sensors in the eye? I don't know how the brain processes this, but the sensitivity of the rods falls nicely into the gap between the green and blue cones. What do you think?
Courtesy of One Minute Astronomer
Could we say that we actually have 4 color sensors in the eye? I don't know how the brain processes this, but the sensitivity of the rods falls nicely into the gap between the green and blue cones. What do you think?
FYI, most lamps refer to a specification called Color Rendering Index, "CRI", which compares the light in ? against natural sun light, at noon, which has somewhat uniform spectral distribution. So a lamp with a CRI of 80 has more spectral components or you are better to differentiate colors than with one with of a CRI of 70 or less. A HPS lamp has a CRI of around 30, as I recall & a color temp of around 2700K. Anything else you need to know about lighting?
A lumen uses the eye reaponse as a measurement filter for determining luminous intensity. Far red and deep blue spec'd LED's measure in radiant power rather than using luminous power because of the human eyes poor response in these spectrums.
Have fun everyone
Rick
A lumen uses the eye reaponse as a measurement filter for determining luminous intensity. Far red and deep blue spec'd LED's measure in radiant power rather than using luminous power because of the human eyes poor response in these spectrums.
Have fun everyone
Rick
Indeed, most white LEDs have a blue LED die and phosphor to convert some of that light to longer wavelengths. Apparently this is far more efficient than combining RGB LEDs to white. The phosphors used for LEDs are related to those used for fluorescent lamps and hence have the same disadvantages.
Source: this article on white LEDs by Mike Wood, from it also comes the attached spectrum of a cool white LED.
Attachments
One of these is fun to play with...3W 50LM RGB Multicolored LED Light Bulb - Worldwide Free Shipping - DX
I am not too sure about this statement "Indeed, most white LEDs have a blue LED die and phosphor to convert some of that light to longer wavelengths. Apparently this is far more efficient than combining RGB LEDs to white"
The problem with mixing Red and Green/Blue led's together is that they are constructed of different semiconductor materials, so they require a diffrent drive voltage/currents. Yes you can put them in series and deal with this but this is not the way one operates an RGB type led, they are driven separately.
To rationalize, my thinking, a blue/green led is made using of similar semiconductor materials, GaN, where as a red is InGaP. The phospher has some degree of quantum loss, so how can it be more efficient than the plain source itself? using Royal blue leds'/phosher is just an easier way to make uniform light from a mono-chromatic source.
LED's are a bit of a scam. I look at $/lumen as a measurement of cost/performance.
A 54W T5HO lamp puts out about 4700 lumens for about $5, and lasts about 25,000 hours with a lumen depreciation of 5%. There are absolutely no LED's on the market that have this cost/performance ratio. It will be along time before an LED will have this cost performance ratio.
The problem with mixing Red and Green/Blue led's together is that they are constructed of different semiconductor materials, so they require a diffrent drive voltage/currents. Yes you can put them in series and deal with this but this is not the way one operates an RGB type led, they are driven separately.
To rationalize, my thinking, a blue/green led is made using of similar semiconductor materials, GaN, where as a red is InGaP. The phospher has some degree of quantum loss, so how can it be more efficient than the plain source itself? using Royal blue leds'/phosher is just an easier way to make uniform light from a mono-chromatic source.
LED's are a bit of a scam. I look at $/lumen as a measurement of cost/performance.
A 54W T5HO lamp puts out about 4700 lumens for about $5, and lasts about 25,000 hours with a lumen depreciation of 5%. There are absolutely no LED's on the market that have this cost/performance ratio. It will be along time before an LED will have this cost performance ratio.
Yes. Most LED bulbs have a CRI similar to CFLs (80-89%) which is quite OK for normal usage. Even though an incandescent has a CRI of 100, I don't think it can hold a candle to daylight as its spectrum is favouring the reds too much in comparison.
Agreed, and precisley the reason why those yellow low pressure sodium lamps to this day are the most efficient lamps.
For this reason they were (and are) used so much in street lighting. But research has found that white light of lower power might actually lead to better visibility under "mesopic conditions typical of night time diriving" (source). Mesopic conditions are around when lighting is low but not quite dark (such as under street lights). Probably the reason why end-of-life LPS luminaires are being replaced with white (LED) light sources over here.
I quote from the article that is my source: "Today it’s typical that a white LED will be at least two to three times as efficacious as a mix of colored LED s in producing white light. This means that with pastel colors, even with a piece of gel for subtractive color in front of those white LED s, they are likely still more efficacious than an additive mix of colored LED s."
This article is a year old, so white LEDs may have progressed even further since then.
@jitter, you sound like you work for Philips or something similar?
I ain't a lamp physist, so I can't prove any of my conjecture
Yes the ole LPS lamp (SOX), is one of the most efficient lamps ever designed.
So much for an audio discussion forum, I make my dough doing lighting, because there ain't any money in audio these days!!
Sorry to say, white light with a large blue spectrum is a lot harder on my eyes at night,
I still say LED's are a scam due to cost/lumen!! Wait til you have to service one of those expensive LED fixtures, i.e.. "no servicable parts contained"
Cheers
Rick
I ain't a lamp physist, so I can't prove any of my conjecture
Yes the ole LPS lamp (SOX), is one of the most efficient lamps ever designed.
So much for an audio discussion forum, I make my dough doing lighting, because there ain't any money in audio these days!!
Sorry to say, white light with a large blue spectrum is a lot harder on my eyes at night,
I still say LED's are a scam due to cost/lumen!! Wait til you have to service one of those expensive LED fixtures, i.e.. "no servicable parts contained"
Cheers
Rick
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This is not the reason why a blue LED with phosphor is more efficacious than a combination of R, G and B LEDs.
The simple fact is that a blue LED + phosphor converts energy to an approximation of white light more efficiently than a blue LED plus R & G LEDs.
Blue LEDs are very efficient. Phosphors are very efficient. R & G LEDs are not.
Look up Visual Purple (rhodopsin). Ever wonder why airplanes and ships use red cockpit light?
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