UV of white LEDs/MR16 LED bulb

Darell

Flashaholic
Joined
Nov 14, 2001
Messages
18,644
Location
LOCO is more like it.
I'm considering lighting some artwork with a large array of 5mm white LEDs. Is there any concern about the UV component of a white LED? Is there any significant UV component to white LEDs? I know fluorescents are the worst in that regard, but I haven't a clue about the various colors of LED. I'll stay away from the "purple" though
smile.gif
 
Well, I held off bumping this for as long as I could. I need to make a decision on buying one or two of these $80 lights, and the UV component will be critical (sure I'd ask the mfg, but our English communications is only getting us so far already).

Craig? You must have some insight on this...

Thanks!
 
Th actual UV output of white LEDs should be pretty darn minimal.

Its got to escape through the phosphor and the relatively thick epoxy capping.

Its only really a problem right beside the die itself as the energy density is pretty high. By the time the light has escapes and filtered through vurtually no UV is going to escape.

As a matter of interest what $80 lamps are you considering, is this still pursuing a white LED MR16?

Adam
 
Darell, have ya looked at Lumidrives 3-Luxeon MR16 fixture? Bet it's cheaper than 48-white LEDs. I *know* the LEDtronics 48-LED MR16 white has got pricetag that'll send ya to the moon....
 
Please point me at the Lumidrive Luxeon MR-16! I'm open to anything, but have never seen that light.

I can't find the Lumidrive when I search for it. Can you throw me a bone?
 
Wow, hold on there. Don't forget white LEDs have a poor colour rendition index (CRI).

You may want to try out those very high CRI (98+) MR16s designed for illuminating art work. I think they have high colour temperatures (4100K) and have very low UV output.

found the link:
http://www.healthylight.com/mr16.htm

Oh yeah, Lumileds have a PSD chart of their white Luxeons on their webpage. Since they use the same semiconductor technology as Nichia, I'm guessing the PSD for Nichia whites would be similar.
 
Well, I've got all kinds of perfectly balanced MR-16 Halogens (Solex). But they're too frigging bright. 50 watts is all they come in, and I need the equivalent of about 10W of light. The art work that I'm illuminating does not need perfect color, either. No worries there.
 
Great info, and great memory!

Yes, this is the MR-16 quest. Lagotroncis has built an improved version of their MR-16 unit, and I'm attempting to buy one (they only read their email about once a week, and I swear they have boilerplate that starts every email with "sorry it has taken so long to repond...")

Here's the guy I'm after: http://www.lagotronics.nl/lagoled.com/english1024768/products/003.htm

They are 60 EUR plus shipping. They still are not mass-producing them, so they're only willing to sell them one at a time. Anybody live near there who'd do me the favor of buying one for me? I'm sure I can get two if I want, but it'll be almost $20USD to ship each one. Gets a bit spendy.
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by darell:
Please point me at the Lumidrive Luxeon MR-16! I'm open to anything, but have never seen that light.

I can't find the Lumidrive when I search for it. Can you throw me a bone?
<HR></BLOCKQUOTE>

Led-Fx is right - it's called the Haloled. He posted their homepage URL, but here is the actual Haloled URL to make your search a little shorter
smile.gif

http://www.lumidrives.com/content/products/integrated/haloled.htm

And don't forget to look at their LED drivers too in case you need an off-the-shelf power supply.
 
Guys, you're doing me proud. Thanks for all the help. I figured Craig would have the straight poop for me. So there's ONE thing I don't have to worry about. Now, onto the more practical aspects of actually getting something I can use.

1. The best price I've ever seen on Solex lights is here: http://eclecticlighting.homestead.com/soluxfullspectrum.html $5.75 for any flavor. BUT, as I've said before, I already have plenty of those, and I don't need to go down that avenue any longer.

2. Those same guys make a really cool MR16 adapter that screws right into a standard socket and includes the transformer. See it here.

3. My local guys at LEDeffects haven't yet impressed me too much with their communications (about every other email goes unanswered - I'm made to feel that they have far more important "big" projects to think about, instead of screwing around with my little one or two piece order. And of course, they're right). One thing is for sure - they only want to sell me a 12VDC (needs to be regulated 12VDC) product. That means it won't be plug-and-play as I'd hoped. For substantial extra cost they'll make me what I want as a "custom" unit. The Lagotronics guys say their product is specifically made for plug-and-play into a 12VAC appliance. THAT's what I'm looking for.

4. The page for the HaloLED states: "HaloLED™ is as easy to use as a conventional light source. All electrical, thermal and optical issues have been considered in the design resulting in a light source that is simply plug and play." And then goes on to contradict that statement with this: "Units cannot be directly retro fitted to existing power supplies / transformers, Lumidrives constant current driver must be installed." I don't consider the need to add a proprietary current driver a "plug and play" device. Still, I really like the thing. Haven't had time to search around and see if I can find a price though. My guess is that they won't be giving them away.
 
The spectrum of the Nichia seems to match the Luxeon.

About the Solux, I remember seeing that there was also 35 watt version.

You might also want to play around (just for fun!) with those new high-efficiency 20 or 30 watt HIR MR16s from Osram or Philips. They're much more energy efficient than any LED MR16 setup.

If you're going with LED MR16s, the best price I've found (I was thinking of getting one as well) is at Lagotronics. A lot of places don't list prices and the ones who do (like Ledtronics) are a lot more expensive.
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by darell:
Well, I held off bumping this for as long as I could

Craig? You must have some insight on this...

Thanks!
<HR></BLOCKQUOTE>

The UV output of commonly available white LEDs (specifically, the type based on GaN/Al2O3) is negligible.

A stranger with a $17,325.00 transspectral imager was kind enough to run a white Nichia and several other LEDs through it and allow me to use his results.

whiteled.gif


As you can see, there is negligible output (probably 1/100th of 1%) below 420nm, and pretty much none below 395nm.
 
Wow, CRI of 85 is great!

The offering from Lagotronics will run me about $75 with shipping, depending on exchange rate. It does sound like a great product. I just have to figure out how to order it at this point.
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by darell:
Wow, CRI of 85 is great!
<HR></BLOCKQUOTE>

They run low only on violet, cyan, and red.

Many fluoro tubes are missing everything except narrow bands of red-orange, green, and blue; and a few weak ion lines peppered elsewhere throughout the spectrum. That's why their CRI is lower - their spectrum isn't continuous.
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>White LEDs don't have a poor color rendering!! The CRI is 85+, a normal cool white fluorescent only has a CRI of 56! <HR></BLOCKQUOTE>

Take a look at the spectrum of the white LED. How even does that look to you?

I don't know where you got that number from but according to Lumileds, their white LEDs have a CRI of 70. Nichia 5mm should hover around that number as well.

Fluorescents use to have appalling CRIs (hence the initial slow take-up) but things have drastically improved. Most CFLs sold now have CRIs of around 80-85. There's even fluorescent tubes with a CRI of 94.5.

And Solux.. well I think the magic number is 98.
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Someguy:
Take a look at the spectrum of the white LED. How even does that look to you?

I don't know where you got that number from but according to Lumileds, their white LEDs have a CRI of 70. Nichia 5mm should hover around that number as well.
<HR></BLOCKQUOTE>

The published CRI of Nichia's white LEDs from last year is 85. If that number is lower now, then they've gone downhill.

A type of non-phosphor white LED I found on the web a couple of years ago has a CRI <45, because it's missing even more spectrum than most fluoro tubes. I haven't seen this lamp with my own eyes though, so I don't know how nasty or nice it really is. Apparently, these are being used on the interior rearview mirror of some mid- and high-end cars as map lights.

I don't at all doubt they have fluorescents with really high CRIs; it's all in the phosphor.
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>The published CRI of Nichia's white LEDs from last year is 85. If that number is lower now, then they've gone downhill.<HR></BLOCKQUOTE>

Thats very odd. The published spectrum of the Luxeon and the measurements you took off the Nichia are almost identical (except for a peak at 610nm for the Luxeon). Also a CRI of 85 usually means a reasonably even spectrum spread and the spectrum of white LEDs are anything but even.

I think the only way to get high CRI LEDs is to improve the phosphor. The broadband yellow is OK but theres a huge chunk missing in the middle. I hope that Nichia will try some sort of RGB phosphor with their new high power UV chips.
 
Top