White Plus other color for Spectrum

Someone asked me if this was a new idea, mixing White and Amber, for "better" spectrum.

No, it's not unique or special, the concept has been around for many years now, getting long in the tooth already.

White LEDs combined with one or more other colors was already done years ago, it is not a new thing at all. In fact, I saw an OSRAM unit supplemented with amber, back about 2001, at the International Society for Information Display show.

In fact, there was a paper already published on this as part of the Society for Information Display. They are a +6,000 member society. http://www.sid.org This year, NASA even presented the mathmatics all the way to a six source color, and technique to cover an astounding amount of the colors the human eye can see. White+Amber is old technology now.


Here is one product that has been on the market and installed already in the customer base since before 27 July 2005:
http://optics.org/articles/news/11/7/19/1/streetlamp2
http://optics.org/articles/news/11/7/19/1#streetlamp2
http://optics.org/articles/news/11/7/19/1


LED lighting may be impressing retailers with its cost-efficient output, but what about the quest for the truly white LED? "It seems that we are close to having a warm white LED," says Gehring. "I think they are currently zeroing in on 3200K, which is still a bit cool in color for many applications. If color rendering is not essential, we'll mix white and amber LEDs to get close to warm white."
http://www.ddimagazine.com/displaya...article_display.jsp?vnu_content_id=1000578526


U.S. Pat. No. 5,752,766 to Bailey et al., is incorporated by reference herein and specifies a system of additive color mixing. The multiple light sources may also contain additional wavelength LEDs such as amber or yellow LEDs. Also broad-spectrum visible white light emitting diodes such as those manufactured by Nichia Chemical Corporation of Japan may be included. A broad spectrum white light source may be added to the plurality of light sources to aid in the overall output of white light or to be mixed into variations of the colored light sources to produce further variations of pastel colors that would not be achievable by using a conventional additive Red, Green and Blue color mixing system.
http://www.freepatentsonline.com/6357893.html


There is even an interior/exterior light that mixes white and amber LEDs, making a more pleasant and balanced color spectrum than the usual bluish/white glow.
http://www.h2onotes.com/apps/newsletter_archive.asp?NGuid={8BFAD612-BC06-460C-9019-035A446651DA}



Both issues are being addressed by the design shown in Figure 20 below. A row of white and a row of amber LEDs are projecting their beams horizontally onto a mirror. As the reflected light reaches the diffuser (1/8" thick translucent Plexiglas), it has spread to about 2 inches.

The translucent Plexiglas serves to diffuse the narrow beams. In essence, Plexiglas sheet acts as the final light source. When one views the Plexiglas surface, one can still see that there are bluish white and amber lights somewhere up there. However, anything illuminated below on the counter receives an uniform warm white light.
More Amber + White


White and Amber LEDs with proprietary optics and control system.
Sealed light engine has no air intake and never needs internal cleaning.
http://intencitylighting.com/IntenCity_1_Street.htm


...but the same approach is used to control different LEDs, such as white and amber LEDs, white light embodiments.
White + Amber LEDs

I took one look at that picture of the LED street light lit up and my first reaction was "yuck, it looks as bad as sodium vapor!". Considering that 3500K to 5000K metal halide is being used more and more in parking lots these days I'm surprised those pushing LED streetlights haven't caught on. One point of using LEDs besides longer life span and the potential for 200 lm/W efficiency is to get away from that horrid yellow of sodium vapor. Another good reason to avoid lower color temperatures is the scotopic response. At typical street lighting levels you can actually get by with about 40% fewer photopic lumens yet still have the same perceived light levels if you go with something like 5500K instead of 3000K. That's also the reason why streets actually look much dimmer lit with sodium vapor that they did with mercury vapor, despite the supposedly higher lumens and efficiency. And aesthetically they just ruin the whole ambiance of the night since they clash with starlight and moonlight.

I think they are currently zeroing in on 3200K, which is still a bit cool in color for many applications.

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First time I've ever heard 3200K described as too cool, and here again interesting especially in light of the fact that they're discussing retail applications. I would think in a clothing store especially you would want the light to be close to sunlight and with high color rendering so you can see how the clothing appears when you wear it in the street. I've noticed also that I rarely see stores using anything less than 3500K. One exception was a local grocery store which was using 3000K. They recently changed out all of their lighting to either 4100K or 5000K. I couldn't really tell which. Either way the store looks way brighter and more inviting now. I used to get bug-eyed when I went in there under those crappy yellow lights. Apparently the employees didn't care for them either.

It seems lighting engineers are still fixated on incandescent as "ideal". I tend to think the work with RGB LEDs is a lot more promising. That paper NewBie linked to in another thread on some studies done was very revealing in that incandescent (both standard and halogen) were the least preferred light source, fairing worse than even regular 5000K phosphor-based LEDs. RGB of 4100K or so seemed to be preferred by a large margin. Maybe the lighting designers should take note here.

why would someone use amber with white led anyway?
Isnt the whole purpose of using led is to get rid of the yellowish-ness of incandescent bulb? why would they go back to incan color by adding amber to the nice white?

I am perfectly happy myself with blue + phospor white. Heck, if the RGB die can give me a more white light, i am all for it. I dont want to go back to that sickly yellow !!!


5000 K - 6000 K Temperature is the best, IMHO

Mixing just a few amber LEDs with white isn't really noticeable as having any yellow tinge. The Philips streetlight may have over done the amber. It is more of a specification item, maybe users aren't ready for cool white on the street, it's too much like a car lot?

Here is a link to some color charts http://intencitylighting.com/IntenCity_photomet.htm#color the CRI is a printable pdf and you use that to compare between a known white source and a test specimen.

The color temp chart shows the yellow diminishes above 3,500K. It's surprising to see the yellow of our incandescent "standard" source.

Hmm doesn't look too bad to me... :shrug:


The pic could have been of a better quality though.

Humm, I wonder if those fellas in the picture of the LED streetlight are Dutch.

Still looks like sickly incandecent/sodium to me. I can't stand sodium vapor colored lights. I can't see detail very well with them. I'm opposite than most people because using a warmer light outside, it actually reduces contrast for me. Grasses/green/yellows tend to all muck together and become one "flat" looking picture that lacks depth. But using a white to even blueish tinted light and it's like it's day light to me. I can see depth and everything is sharp. I've noticed this even when the bluer/colder light puts out less lumens than the wamer/amber one, it seems brigther.

Perhaps my eyes don't pick up yellows as brightly as others. I don't have any color blindness, but perhaps "worn out" receptors of warm colors.. hehe

Same concept here as with LumiLeds Warm White leds. They added some orange/red phosphur or similar to the mix of yellow to warm it up. Does anyone know if any product is actually using them or did they kinda die away?

I personally would rather have RGB leds instead of add Amber to make up for the lack of red response. Of course there's more cost in tuning 3 leds to make white than just dialing in the extra amount of amber....

jtr1962 said:

At typical street lighting levels you can actually get by with about 40% fewer photopic lumens yet still have the same perceived light levels if you go with something like 5500K instead of 3000K. That's also the reason why streets actually look much dimmer lit with sodium vapor that they did with mercury vapor, despite the supposedly higher lumens and efficiency.

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That isn't my perception, having lived through the transition from incandescent to the blue mercury lights to the Halloween orange of the high-pressure sodium. The latter are quite blasting bright to me, and as they took over I noticed that low clouds on winter nights got so brightly lit with orange light reflected off fresh snow that I could read by it in an otherwise dark back yard.

If there is a difference other than color, I would say that perhaps the orange lights might appear more concentrated near the source, as orange is brighter to the photopic vision (which is active near the lights) but less so far away (where scotopic takes over). I've noticed a similar effect switching between colors on my Eternalight Rave'n in a dark room; red is sharply confined to its hotspot, while blue "fills" the room with light even though its hotspot is seemingly not as bright as the red.

There *are* a lot of lights I'm seeing around now that aren't orange at all, but seem much more "white".. what are those? Has someone "tuned" high-pressure sodium to give more blue?

Lastly, here's an odd story to relate: my GF and I went camping next to the ocean just east of Point Mugu (near Camarillo, CA) and the ranger booth had a big LED light using rows of white and *orange* LED's. Apparently someone wanted to simulate that Halloween orange of sodium vapor with LED's, and sold one to the state parks dept. :shrug:

The picture quality isn't too bad, but notice that it isn't a dark night at all. Areas that are well beyond that of the luminaire are already illuminated, and the sky is quite bright. A true night-sky picture would show no luminance from the sky.

Another problem if the light is too orange: when it's important to read things like a map, a bus schedule, a bus pass/ticket, or even a lottery ticket, it just isn't possible. Try this under any sodium light and report your results.

Canuke said:

There *are* a lot of lights I'm seeing around now that aren't orange at all, but seem much more "white".. what are those? Has someone "tuned" high-pressure sodium to give more blue?

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Probably metal halide although there are HPS with better color rendering but still an orange look. Metal halide of 3500K to 5000K are being used more and more in parking lots. Here where I live they've virtually displaced sodium for that use. Now if we could only get them in streetlights. The old mercury vapor were too blue and also too dim. The sodium vapor are too orange, and also too dim. The metal halide seem a perfect white, and they don't ruin the ambience of the night as a result. They also give 100 to 120 lm/W, depending upon size. HPS gives I think 120 lm/W but in actual use looks dimmer because of the very low color temperature.

I think your experience with the sodium lights reflecting off clouds has more to do with the fact that long-wavelength light travels further in the atmosphere than with them being brighter. The mercury vapor didn't stand a chance of reaching the clouds. I notice this effect when it snows. The whole sky is lit up with an eerie orange glow. I remember when the mercury vapor were replaced in the early 1970s they put one 250 watt (~25,000 lumens) sodium light in place of a 400 watt mercury light (~20,000 lumens). Supposedly it was about 25% brighter while using 37.5% less power but almost to a person everyone complained that the streets were too dark. I don't think studies of photopic versus scotopic lumens existed at the time. Even if they did, I don't believe metal halide was a viable option as it is now.

BTW, in some places NYC has used metal halide street lighting to good effect. Here is a picture of 42nd street I took last year (sorry about the blurriness):

I have heard the natural colour shift with age as described as going from using D65 to illiminant A (daylight to incandescent), the eye loses the blue end (a bit like with cataracts)

I am surprised by the apparent like for 'warm' lights, I prefer mine stone cold, better colour as mentioned before.

Having said that, I much prefer low pressure sodium at night as astronomers (like me) can more easily filter them out, which you can't do so easily with other kinds of light. (Of course I would prefer that we didn;t have street lights.... EXCEPT for accident prevention where absolutely neccessary, we'd save a large amount of electricity too. Also be good for flashaholics too!)

Cheers

PEterW (who lives under the manmade light dome that calls itself London(UK)!)

I have an article right on topic http://patmullins.com/sodiumpollution.html and another on the streetlight matter http://patmullins.com/newlook.html

The conclusion is that sodium light is just for efficacy' sake, it's the wrong color light for the application, but using a whole bunch of it sort of gets to the target.

? Like aiming a fire hose beside the fire, hoping that some over-spray will hit the fire? Killing flies with a shotgun?

If we merely use the correct light, we can do with a lot less than outdated standards require.
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PS - I'm new here and couldn't figure out where to activate or link an avatar. Any help is appreciated.

Well, with LEDs, there are alot of spectral possibilities/options, so it should get really interesting in the future.

NewBie said:

Humm, I wonder if those fellas in the picture of the LED streetlight are Dutch.

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Hmm, could very well be, but I can't tell for sure because their clogs aren't in the pic... :nana:

The first time that I saw those ugly low-pressure sodium streetlights was when I moved out to California. I can't imagine the number of car accidents we would have in Michigan if we had to rely on that kind of light to drive in the snow or pouring rain.

I think in snow or fog the yellow/orange color causes less blinding, and help in seeing better than white light... :thinking:

B@rt said:

I think in snow or fog the yellow/orange color causes less blinding, and help in seeing better than white light... :thinking:

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I remember when they switched to the orange lights in front of the house, it certainly was alot easier to see further in the fog.

However, in the rain, the street markings (paint), were alot harder to see.

B@rt said:

I think in snow or fog the yellow/orange color causes less blinding, and help in seeing better than white light... :thinking:

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I've heard conflicting views on whether or not this is true. Anyway, these low-pressure sodium lights just aren't that bright. That's more of an issue for me than the color.

Originally Posted by B@rt
I think in snow or fog the yellow/orange color causes less blinding, and help in seeing better than white light...

asdalton said:

I've heard conflicting views on whether or not this is true. Anyway, these low-pressure sodium lights just aren't that bright. That's more of an issue for me than the color.

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The vapor molecules (in fog) reflect the spectrum of whiter light, that medium reflects less from the yellowish light. The lower brightness is because the amber light is not tuned to our spectrum, we have poor visual acuity with amber. But it does help prevent our bumping into large objects in the night.

Most residential area lighting is preferred as whiter or bluer because object recognition is far better with less lumens. There are no official studies indicating that light is a crime prevention, but at least observers can accurately recount for silver, red, blue and other car or clothing colors.

Well, the amber street light is less disturbing at night, when I'm trying to sleep, at least...