# Violet-based white LEDs



## jeffkrol (Jun 5, 2013)

Solcielo lawrencia said:


> I'm wondering if anyone knows more about violet-based LEDs that use three phosphors (blue, green, & red) to produce white light. Apparently, there aren't any spectral dips (cyan region) and violet spectrum absence that plagues royal blue-based white LEDs. As a result, light appears much more white and it obviously covers the violet spectrum. Soraa, the manufacturer of violet-based white LEDs, claims a CRI of at least 95 and, if I'm to believe their marketing, will probably replace blue-based LEDs in the future.
> 
> In terms of color preference, human subjects overwhelmingly prefered violet-based LED white light to blue-based LEDs
> 
> ...


Same concept, different company. I've posted this numerous times in the past..
http://www.yujiintl.com/high-cri-led-lighting










2700k.. a bit warm for my taste:
The 5000-ish's are always "out of stock".. 









5600k


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## gus6464 (Dec 19, 2011)

Take a look at luxeon cob. Its a white led with blue, red, violet emitters. CRI is in the 95 range.

Sent from my XT1060 using Tapatalk


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## Solcielo lawrencia (Dec 30, 2013)

Jeff, have you made any DIY lights using the violet-based LEDs?


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## jeffkrol (Jun 5, 2013)

Solcielo lawrencia said:


> Jeff, have you made any DIY lights using the violet-based LEDs?


No, I've got a small tank that I want to try the dimmable "pre-builts" on..
http://store.yujiintl.com/products/high-cri-led-spotlight-1
These w/ 60 degree optics..
Beam angle on the PAr lamps are too restrictive, and a bit pricy for a test:
http://store.yujiintl.com/products/high-cri-led-par38-lamp 
The loose chips are SMD's which I really don't want to deal w/ at this time.. I tried to get a "guinea pig" but to no avail.. (sorry people, can't buy everything)..

I find nothing that wouldn't make them superior for one color tanks though..


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## Solcielo lawrencia (Dec 30, 2013)

If I were to use the SMDs, how would I attach that to a board or heat sink? Just solder it?


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## FlyingHellFish (Nov 5, 2011)

Interesting, I'm sure we're see LED advance to a level where one white light will cover whatever spectrum you desire.
But, wouldn't the same goal be reach if you just add in the spectrum you're missing? Say, Violet led, or Blue or Deeper Blue and High Red?

It seem we're seeing the same level of interest in DIY Led, much like DIY Co2 builds. I'm just curious why you guys have such an desire to get a specific spectrum? 
Not why have the ability to adjust the spectrum with individual light source instead of grouping all of them in one white led?

**And no, I'm not being passive aggressive, I'm serious here. I'm interested in hearing your thoughts. Is there any particular tank you like that went this route?


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## jeffkrol (Jun 5, 2013)

FlyingHellFish said:


> Interesting, I'm sure we're see LED advance to a level where one white light will cover whatever spectrum you desire.
> But, wouldn't the same goal be reach if you just add in the spectrum you're missing? Say, Violet led, or Blue or Deeper Blue and High Red?
> 
> It seem we're seeing the same level of interest in DIY Led, much like DIY Co2 builds. I'm just curious why you guys have such an desire to get a specific spectrum?
> ...


My 2 cents:
I still like the channel control of  a RGBWh multi LED array..
but this is not for everyone.
It is about the only thing that doesn't make me jump cartwheels over this tech.

for those that subscribe to the philosophy "closer to daylight the better"
these violet/phosphor chips are darn close to perfect..

One tech worry is the longevity of the violet "base" diode.. They don't have a very good track record to date (I may be outdated a bit here though)

Secondly all one chip LED's (w/ the possible exception of the "no chart" Veros and of course apparently thes new ones) are deficient in the cyan area except w/ this (cyan) as a separate diode..
compounding the problem is "fake" cyans w/ blue and green diode pairs being sold as "cyan"..
Even w/ those( real cyan) there is a small "miss" section..

I still see the possibility of blending EVEN these doped violet chips.. say 2700k w/ th 5600k..for both plant growth and visual appeal..

Taken a different way.. we went from inefficient "black body" sources (incan. bulbs) to "punctuated spectrum" efficient lights which reveal their weaknesses by having poor "color fidelity" to the real world..
to efficient LED's that are broader in spectrum but have the same weaknesses , only (arguably) to a lesser degree..
Those that need "real" daylight i.e photography, stage lighting, product lighting spoke and "we" have been fudging ever since. Even to the point of realizing CRI measurements aren't even accurate enough.. you can have a high CRI LED w/ a poor color rendition of "some" color/tones.. 
so now "we" are trying to get the holy grail of lighting .. a "black body" source in an energy efficient "digital" package so to speak..


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## Solcielo lawrencia (Dec 30, 2013)

FHF,
It's primarily to have colors look good. Typical blue-based LEDs suck in terms of color rendition and it bothers me quite a bit that I'm noticing that colors are 'missing'. The second reason is simply to have plants grow well by providing the full spectrum available for them to do as they please with it. This makes it easier than having to use a bunch of multi-colored carnival lights. Also, using colored LEDs causes spectral spikes which exaggerates these colors. Ideally, there will be a light that provides a flat curve from 400-700nm.


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## jeffkrol (Jun 5, 2013)

Solcielo lawrencia said:


> If I were to use the SMDs, how would I attach that to a board or heat sink? Just solder it?


There are some good tutorials of SMD soldering using an electric fry pan. 
"good" soldering irons can be used as well as heat guns..

Requires a "board" of course and special solder.. ect.. ect.. 

I suppose an easy way would be to "unsolder" a strip of 5630's and reflow the new ones..

Or spend $200 for 5 meters..(300 LED's)


> High CRI LED Ribbon - 5630 SMD - 60 LED/M - Unit : 5M/REEL


w/ 3W quality emitters going for $3 each the pricing is not bad.. watt for watt (relatively speaking) $1.33/watt


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## Greystoke (Jul 24, 2010)

Solcielo lawrencia said:


> FHF,
> It's primarily to have colors look good. Typical blue-based LEDs suck in terms of color rendition and it bothers me quite a bit that I'm noticing that colors are 'missing'. The second reason is simply to have plants grow well by providing the full spectrum available for them to do as they please with it. This makes it easier than having to use a bunch of multi-colored carnival lights. Also, using colored LEDs causes spectral spikes which exaggerates these colors. Ideally, there will be a light that provides a flat curve from 400-700nm.


A very acceptable opinion, although colored LEDs can be useful as compensation in under supported regions of a spectrum.
Complicated LED technology drives-up the price.


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## Solcielo lawrencia (Dec 30, 2013)

Greystoke said:


> A very acceptable opinion, although colored LEDs can be useful as compensation in under supported regions of a spectrum.
> Complicated LED technology drives-up the price.


But the problem of the disco-effect comes into play if there isn't a diffuser to help blend the colors. Imagine being a fish and looking up and wondering "WTF is that green light? And that purple one? And the red one? And the orange one? Why isn't the light just white?"


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## Greystoke (Jul 24, 2010)

That may indeed be a problem if it actually stresses the fish.
Perhaps an opaque screen may help.

I like the simple things in life.


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## Solcielo lawrencia (Dec 30, 2013)

After looking through the Yuji product specs, the violet-based LEDs provide much less lumens than blue-based LEDs. E.g. violet is 800lm, while blue is 1200lm. I'm assuming this is primarily due to the spectrum in the violet and deep reds that our eyes can't perceive as brightly. But in effect, the violets would actually provide more useable light to plants, am I correct?


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## FlyingHellFish (Nov 5, 2011)

^ Yes, that is one way to look at it. A light can rated at 1000 lumens but if it is lacking in the spectrum plants need, it wouldn't as efficient as a bulb made for growing plants. So in reality, you can't judge a light based on how "bright" it looks.

For example, a typical grow-op would want to lower their power usage and maximize their yield. Since it's not a fish tank or an art gallery, they forgo the CRI, lumens and focus on giving the plants what they need. 

Light A - 1000 lumens , yet lacks high red and low blue
Light B - 900 lumens, spiking in blue and high red < - Better choice.

I'm a bit surprise at the maturity of this thread, thought it would be another flame war. 

Forgot to add: I don't quite see where the need for this comes from? The hobby is doing very well with the LEDs on the market right now and I still see amazing scapes using only fluorescent (T5HO, CFL, HQI).


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## Greystoke (Jul 24, 2010)

Solcielo lawrencia said:


> After looking through the Yuji product specs, the violet-based LEDs provide much less lumens than blue-based LEDs. E.g. violet is 800lm, while blue is 1200lm. I'm assuming this is primarily due to the spectrum in the violet and deep reds that our eyes can't perceive as brightly. But in effect, the violets would actually provide more useable light to plants, am I correct?


Yes you are correct. 
Indeed, the "Blues" emit more light in the visible region than the "Violets". Consequently they generate more "Lumen" for the same effort.


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## Greystoke (Jul 24, 2010)

FlyingHellFish said:


> Forgot to add: I don't quite see where the need for this comes from? The hobby is doing very well with the LEDs on the market right now and I still see amazing scapes using only fluorescent (T5HO, CFL, HQI).


I had to make that choice a few years ago when I built my new tank (see: "http://www.plantedtank.net/forums/showthread.php?t=496961&highlight"]. I realized that if I were to have a champion tank under T5HO's, I would probably never change to LEDs for fear of destroying what I just built.
So, I decided on LEDs come Hell or High Water (which both came to visit, BTW :frown.


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## Solcielo lawrencia (Dec 30, 2013)

FlyingHellFish said:


> Forgot to add: I don't quite see where the need for this comes from? The hobby is doing very well with the LEDs on the market right now and I still see amazing scapes using only fluorescent (T5HO, CFL, HQI).


It's not about having nice scapes or fish tanks but having nice scapes and fish tanks that look natural and calm to the eye. Most people don't notice these differences in quality because they have nothing better to compare to, side by side.

For example, daylight fluorescent bulbs have a notable green spike which makes green excessively bright relative to the other colors. It's also a very narrow green band with no gradation. It's not initially obvious, but over time, it becomes noticeable. In editing photos, I have to turn down the green band to make it balanced with the other colors. Similar issues with sodium vapor or MH lights.

Our eyes prefer to see an even spectrum from violet to far red. It's simply the most relaxing. Thus, I want light that is as natural as possible because it allows our eyes to be calm and relaxing, which makes us calm and relaxed.


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## Greystoke (Jul 24, 2010)

Solcielo lawrencia said:


> . . . Our eyes prefer to see an even spectrum from violet to far red. It's simply the most relaxing . . .


Are you sure about that? Our eye sensitivity tests do not seem to support that. To us, a particular mixture of red, green and blue - not forming a continuous even spectrum - generally comes across as "white", while being unable to detect either the red, the green or the blue.

It's a difficult subject to support/defend by an amateur like me.


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## Solcielo lawrencia (Dec 30, 2013)

Greystoke said:


> Are you sure about that? Our eye sensitivity tests do not seem to support that. To us, a particular mixture of red, green and blue - not forming a continuous even spectrum - generally comes across as "white", while being unable to detect either the red, the green or the blue.
> 
> It's a difficult subject to support/defend by an amateur like me.


I can tell but I'm also much more sensitive than the average population. I can even see fluorescent flicker that no one else seems bothered by. Further, in lab tests, people prefer more natural light and make less mistakes (they don't overshoot as much) when reading.

The reason screen displays use RBG to produce light comes from the fact that our eyes only have three color photoreceptors. (A small minority have four color photoreceptors.) It was assumed, just like in audio perception, that we can only perceive what we are consciously aware of. However, this was a mistake as we perceive much more than that. This is the reason why some TV manufacturers introduced yellow LEDs in their display to provide a more vivid color reproduction. This was also the reason SACDs were invented, because we hear sounds in far greater a dynamic and tonal range than what our ears can perceive.


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## Greystoke (Jul 24, 2010)

Solcielo lawrencia said:


> I can tell but I'm also much more sensitive than the average population. I can even see fluorescent flicker that no one else seems bothered by. . .


Amazing.
Now I understand that's why you are so keen on this kind of development.




Solcielo lawrencia said:


> . . .Further, in lab tests, people prefer more natural light and make less mistakes (they don't overshoot as much) when reading.


 Didn't know, but I'll certainly keep that in mind.
Do you - perhaps - have any links on this?


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## jeffkrol (Jun 5, 2013)

FYI.. related to the 425nm "blue" based LED's..
http://www.supergrowled.com/products/#sgl6









not really seeing much of a 425nm spike though..


> The phosphor coat used on the very high power 425nm blue base LED is our own proprietary formula, used to give us the strong full spectrum coverage we employ in our luminaires


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## Solcielo lawrencia (Dec 30, 2013)

Greystoke said:


> Didn't know, but I'll certainly keep that in mind.
> Do you - perhaps - have any links on this?


Eye movements worse at slower light frequency (Hz):
http://hfs.sagepub.com/content/28/1/75.short

Imperceptible 100 Hz flicker impairs task performance...
http://www.sciencedirect.com/science/article/pii/S0272494408001011

... But compared to 20-60 Hz flicker, it's actually better.
http://lrt.sagepub.com/content/27/4/243.short

Fluorescent light causes headaches and eyestrain:
http://lrt.sagepub.com/content/21/1/11.short

If you hate your office, change your bulbs to 'warm-white'. 'Daylight' bulbs make you hate your work.
http://lrt.sagepub.com/content/25/2/71.short

Want to make up with someone? Do it under warm-white light. Avoid them under cool white.
http://link.springer.com/article/10.1007/BF00996485


The science of light as it affects human behavior is quite fascinating. Poor lighting makes you read slower, makes you hate your work, makes you want to avoid someone. That may be the reason people hate cars that have super bluish headlamps. But good lighting can improve concentration, makes you like your work, and makes you want to have make-up sex. Perhaps that's why candle-lit dinners are much more romantic than fluorescent-lit ones. 

Also, the issue of LED flicker has been of some concern for me.
http://ieeexplore.ieee.org/xpl/logi...re.ieee.org/xpls/abs_all.jsp?arnumber=5618050


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## jeffkrol (Jun 5, 2013)

Solcielo lawrencia said:


> Also, the issue of LED flicker has been of some concern for me.
> http://ieeexplore.ieee.org/xpl/logi...re.ieee.org/xpls/abs_all.jsp?arnumber=5618050


Interesting.. but..... 


> Classic data from Kelly for modulation of large (30 degree radius)visual fields at different light levels from 0.03cd
> m to 5000cdm
> showed that beyond 100Hz, even flicker with 100% mod-ulation was hardly ever directly visible, either
> centrally or peripherally.’Critical flicker
> ...


http://lrt.sagepub.com/content/45/1/124.full.pdf+html


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## Solcielo lawrencia (Dec 30, 2013)

jeffkrol said:


> Interesting.. but.....
> 
> http://lrt.sagepub.com/content/45/1/124.full.pdf+html


There is a difference between conscious perception and cognitive perception; you don't have to be consciously aware of something in order for it to affect your behavior. However, I don't see a point from the article, "Flicker can be perceived during saccades [eye movement] at frequencies in excess of 1kHz", you linked which is about perception of flicker.

Also, I am quite aware of those damn Audi's with LED tail lights that flicker. I want to rear-end those damn shiny German cars. :icon_twis


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