# Is it possible to have a 100 CRI LED?



## poiihy (May 24, 2015)

Is it possible to have a 100 CRI LED or is the technology not there yet?


----------



## mattheww50 (May 24, 2015)

I am not sure you can get quite to 100, but you can probably get very close. It is a question of how much time and money are you prepared to put into the phosphors, and how low an overall efficiency are you willing to live with. Since Energy saving (total cost of ownership) is what drives the LED lighting market, very expensive low efficiency LED's aren't likely to be very popular, so today the market for such a device is simply too limited for manufacturers to make such a product.

For example GE used to make 5000K F40 Fluorescent lamp with a CRI of 96 IIRC (Chroma 5000 series). It was fairly expensive, and had about half the lumens per watt of the 'best' F40's, in fact the performance was so poor that the lamp was discontinued because it could not meet the mandated efficiency standards. While your average Home Depot F40 cool white Fluorescent is about $1, the high performance, high CRI fluoros like the GE SPX line are more like $7-$8 each at wholesale by the case. the market for these lamps is fairly limited, while they provide excellent color rending (and are ideally suited for some 'high end' applications, they are too expensive for general use.


----------



## FRITZHID (May 24, 2015)

In one LED.... No.....
Not yet anyway.


----------



## SemiMan (May 24, 2015)

Ask not if ... but why.

Why would you want to bother.


----------



## poiihy (May 24, 2015)

FRITZHID said:


> In one LED.... No.....
> Not yet anyway.



Can you have it with multiple LEDs?
It would be nice to have a 100cri light fixture.


----------



## SemiMan (May 25, 2015)

Why? For what benefit?


----------



## RetroTechie (May 25, 2015)

I don't see any _fundamental_ difference between mixing LEDs that use different phosphors to combine into some 'ideal' color spectrum, or building a single LED that uses some optimal mix of phosphors to do the same. So there's no reason why one couldn't build a 100 CRI LED *in theory*.

For _practical_ LEDs, it's a balance between efficiency and how close you get to a nice color spectrum. Wikipedia article on CRI had a link to this manufacturer:

http://www.yujiintl.com/high-cri-led-lighting

Scroll towards the bottom of that page, and look at the product figures for 93/95 vs. 97 typical CRI. The lm/W difference is considerable. But could you tell the difference in color? Probably not. Could you tell the difference in photographs made under such light sources? I doubt it.


----------



## poiihy (May 26, 2015)

SemiMan said:


> Why? For what benefit?



Better light quality... duh?


----------



## SemiMan (May 26, 2015)

Duh! ... Would be that response as CRI is not about light quality but about replicating a black body or the sun. 

Better subjective quality is at less than 100 CRI and a wide gamut lower CRI light would usually be viewed more favorably versus high CRI.


----------



## recDNA (May 26, 2015)

I doubt there will ever be a commercially available 100 CRI LED. Ever. If you need 100 CRI easier to get with an incandescent.


----------



## markr6 (May 26, 2015)

SemiMan said:


> Duh! ... Would be that response as CRI is not about light quality but about replicating a black body or the sun.



I'm interested in making the SUN replicate a Nichia 219


----------



## night.hoodie (May 26, 2015)

markr6 said:


> I'm interested in making the SUN replicate a Nichia 219



Perhaps you used the wrong smiley


----------



## knife99 (Jun 5, 2015)

oled technic is a good choice for high CRI


----------



## Anders Hoveland (Jun 5, 2015)

LEDengin makes a 3000K emitter with 97 CRI, but the lowest power it is available in is 10W, and it is fairly expensive (you will need their special substrate board to mount the LED on too). These LEDs are being incorporated into commercial lamps for use in museums and institutional art galleries.
http://www.sssplc.com/pr/industrys-most-compact-led-emitter-for-70

This seems to be about the upper limit of what is possible from blue emitter LEDs combined with phosphor. It is important to point out here that these LEDs are 3000K, it would be harder to get this high of a CRI value at higher color temperatures.

I also suspect that in the distant future there is going to be more research and development into creating very high CRI lamps that are more efficient. While TrueWhite and Brilliant Mix technology, that use a separate emitter to generate the red wavelengths in the spectrum, already exist and have already begun appearing in some commercial spaces, these fixtures still are not considered _really high_ CRI. I mean, I have one and the color rendering (90-92) is fine for an office space, but it is a little difficult to imagine it being used to illuminate paintings in an art museum.

I also want to point out that "90 CRI" does not mean the light is 90% as good as a 100 CRI source. That type of simplistic understanding fails to truly grasp how the color rendering index is actually works. An alternate way to look at it is this way: 90 CRI is twice as good as 80 CRI, 95 CRI is twice as good as 90 CRI.


----------



## Anders Hoveland (Jun 5, 2015)

If the technology does ever get there, and 100 CRI LEDs do become widely commercially available, there is also the question whether we actually _really_ want 100 CRI, whether that is really optimal. I suspect for comfortable general indoor lighting purposes it may be more optimal to have LED light with a lower ratio of the shorter indigo <445nm wavelengths in its spectrum (and without violet). This may cut into the CRI a little, and make blue colors look somewhat less saturated, but it would still basically be a full spectrum light source with 97-98 CRI.

I remember reading an interview from one Philips executive, while explaining the technology behind Philips's new CrispWhite LED technology for clothing retail applications and why a 430nm emitter was chosen to supplement the spectrum, he commented that the shorter violet wavelengths were not really good for people to be under, that they were more for sterilization. I will try to find the specific article. In fact another company called Vital Vio is marketing violet-emitter white LED fixtures to hospitals, since the presence of violet wavelengths supposedly helps disinfect the environment (it's questionable whether it really does or not). These violet-emitter LED fixtures are not even high CRI either (a technical specification brochure from the company states 82 CRI).


----------



## Anders Hoveland (Jun 5, 2015)

poiihy said:


> Can you have it with multiple LEDs?


Yes, it is possible, but when you try to combine several types of different color emitters together it begins to create some design challenges. The light has to be diffused and mixed first. If the light is just coming straight out from the emitters the beam will not have a uniform color consistency. That is why it is generally much simpler to design an LED lamp that only uses a single type of emitter. If the light is not diffused, it is at least important that the different color emitters be as close together as possible, ideally on the same chip. When we are talking about using more than just 2 or 3 different wavelengths, that really makes things more challenging.




SemiMan said:


> Why? For what benefit?


I think he means he wants something that feels exactly like sunlight. Light quality, how the light "feels", and CRI are not quite the exact same thing.
I have a 95 CRI 3000K LED lamp and, although the color rendering in really good, the light still does not really feel _exactly_ like a halogen spotlight. But once you get to 100 CRI, you would be guaranteed it would be the same.
r


----------



## TEEJ (Jun 5, 2015)

After you say you want it "like the Sun"...you have to say "At what time and coordinates on earth?" What about on the moon?


The dawn and dusk, mid day and mid morning, arctic and equatorial light all have different effects.




And CRI is not the only way to characterize light.


----------



## Anders Hoveland (Jun 5, 2015)

TEEJ said:


> After you say you want it "like the Sun"...


I am not even sure the sunlight reaching the surface of the earth is really exactly 100 CRI either.
After being attenuated through the atmosphere, it is not really the spectral distribution of a blackbody curve.
When you go from 5900K (surface of the sun) down to 4000K (ray of sunlight), there is bound to be some spectral distortion.

True 4000K blackbody probably has a more magenta color tint than 4000K sunlight too.

For higher color temperatures, is the black body curve really the most ideal?


----------



## SemiMan (Jun 5, 2015)

By definition sunlight, under specific conditions, on earth, is 100 CRI.


100 CRI is a near meaningless goal based on a very short human history of hot wire lighting that never existed in nature.

4000k black body as a light source again is not "natural"


----------



## handyman85 (Jul 27, 2015)

Klauf lighting just rolled out a Kickstarter where they offer 94CRI undercounter lights. that's the closest to 100 that i've seen.


----------



## Anders Hoveland (Jul 27, 2015)

The Sylvania ULTRA HD Professional Series line of PAR lamps is 95CRI, the highest of any retrofit LED bulb I am aware of (they are a little overpriced though). These were designed for places like expensive hotel lobbies.

I have some Oslon SSL150 emitters, rated "96 CRI typical", and judging by the light quality and color rendering I believe it. I got them in 4000K. Some of the really high-end museum quality LED spotlights are 97CRI at 3000K, but they sacrifice some efficiency to get there.

Then there are violet-emitter LEDs, made by Soraa and Yuji. Using a violet wavelength emitting diode allows blue LED phosphors to be used, which makes the highest CRI possible. The light from these LEDs feel different than LEDs that use normal blue-emitter technology, and are rated 97-98 CRI.
(There are some reasons violet-emitter LEDs may not be as suitable for normal use though)


----------

