New Luxeon: Rebel

[Kinnza]

Hi Kinnza:

This is the first I've heard of a conversion factor for WHITE LED's (blue with yellow phosphor) that exceeds the ballpark of 240 lm/W(emitted). Likewise, the numbers I've heard for RGB tend to be around 270 lm/W(emitted). I can see where the RGB number could be tweaked if you stretch your definition of white and let CRI drop, but 400 lm/W seems like a mighty stretch. I'd like to learn more... got any references?

Yes, blue with yellow phosphor white LEDs have their maximum LER (Luminous Efficacy of Radiation=lm per emited watt) at about 240lm/w, with current phosphor technologies. Although perhaps its possible to increase it a bit by improving phosphors efficiency, or selecting emission spectra with low color rendering. The 240lm/w figure is achieved by reducing the theoretical good rendering white spectra (~330lm/w) by 25% of losses at phosphors. Either reducing this losses or selecting spectra about 400lm/w (greenish white for applications without color renderings constrains) potentially could achieve white sources over 240lm/w (at 100% wall plug efficiency).

But RGB solutions with 3 or 4 chips was theorized long ago as capable to offer higher efficiencies, due to both no phosphor losses and emission spectra exceding 330lm/w. In fact, while seeking for some article showing it, i realized that the 400lm/w figure comes from a high CRI (>80) white spectra, and that 435lm/w spectra (CRI=40) is possible.

Read the article called "Symulation analysis of white LED spectra and color rendering" at the "CIE Expert Symposium on LED light sources" (Pdf).

There is a ilustrated presentation about same topic from Everfine.

In the page 20 of the 2001 OIDA roadmap
there is a example of a 399lm/w RGB spectra with CRI=80.

More generally, at "WWW.LIGHTEMITTINGDIODES.ORG" you can found more info. Specially, this two pics:

To finish coming back to topic, anybody has wired the Rebel from top?

 

[evan9162]

The entire top of the device is covered in the same silicone that the optic dome is made from - this prevents soldering to the top contact.

See page 12 of this document (Luxeon Rebel assembly and handling):

http://www.luxeon.com/pdfs/AB32.pdf

 

[niemidc]

I'd have to say that the Rebel may be totally not what flashlight modders are looking for, yet be an enormous success. For every bin "Q2" CREE sold to you guys, there may be 10,000 55 lumen/watt Rebels sold for use in things that look nothing like a flashlight. Try to keep this in perspective.

I'd also say that while 240 lumens/watt (let alone 300) is pretty far away, long before we reach that point most of the lighting industry will have been totally revolutionized. Think not just about how much light you can get from a given amount of power, but also how much light you can get with a certain amount of heat dissipation. As you approach 50% overall energy efficiency you start to get the ability to pack a lot of light in a very small space. That opens up applications that have never existed before.

Picture this for starters: replace every one of the dozens of incandescent light bulbs in your car with LEDs you never have to replace. It's doable now, and very close to economical when you consider you can dispense with the sockets too.

Next picture a few Rebels (or similarly small surface mount LEDs) in series covered by a diffuser on a tiny circuit board that emerges from a standard light bulb base, maybe twice the cost of a compact fluorescent but no mercury, unbreakable, 5x the life, higher efficiency, better color rendering, and smaller than a halogen, fitting anywhere you like. Then, get rid of the silly old-fashioned base and design this into the lamp, as there's no need to ever replace the bulb. Looks nothing like a flashlight, and totally uninteresting to many of you, but it would change the world in a very big way. And this is happening right now before your eyes.

Think outside the flashlight.

 

[PhantomPhoton]

Think outside the flashlight.

Never!

:lolsign:

It's hard to say right now how well these rebels will do, in flashlights or otherwise. But I think it is safe to say this particular LED isn't the part "we" have been waiting for. But I wouldn't put it past some crazy people here to make decent use of them in portable lighting anyway.

 

[TorchBoy]

Not strictly accurate - the Q2 bin has only just been released to consumers. Romour is the Q bins have been out for a while - probably since November when they were originally scheduled - it's just that somebody big has been gobbling them all up.

Ooh, is that a sniff of a conspiracy? Who could it be?

Briefly restated, in order to achieve anything above ~240 lm/W of white light you're going to need the equivalent of a perpetual motion machine. Using your tongue-in-cheek number of 300 lm/W, it means an efficiency of 125% - getting OUT fully 25% more power than you put IN. If you understand the laws of physics and thermodynamics, you know that you can never, and I stress never, get more out than you put in.

Personally, I think the confusion arises because people don't grasp that a lumen is simply a measurement of power. It's called "photopic" power because it is weighted for the response of the human eye. If, on the other hand, (as EngineeringGuy also said) we threw away the word lumen and used "radiometric" power instead, the radiometric units of light are watts. Now you can look at electrical power input in watts, and light output in watts, and immediately see that the ratio cannot exceed 100%.

Yes, there is a bit of confusion here. I don't put any electrical energy into a candle when I light it or when it's burning. So by your definition its efficiency is, um, infinite. Hey, that's more than 100%!

It's obvious we can have more than 100% for the ratio of output light energy to input electrical energy, so I have to side with CM (even though he thinks he was mistaken) and say it's not inconceivable that we could have 300 lumens per watt of input electrical energy in a future roughly-LED-like device. I know very well that it wouldn't exceed 242.5 lm/W total input energy if you stayed with an ideal white wide-band spectrum.

:touche:

Either way, it's not going to be a Rebel. Like niemidc said, things will have changed big time by then.

Cheers.

 

[soffiler]

...Yes, there is a bit of confusion here. I don't put any electrical energy into a candle when I light it or when it's burning. So by your definition its efficiency is, um, infinite. Hey, that's more than 100%!

It's obvious we can have more than 100% for the ratio of output light energy to input electrical energy, so I have to side with CM (even though he thinks he was mistaken) and say it's not inconceivable that we could have 300 lumens per watt of input electrical energy in a future roughly-LED-like device. I know very well that it wouldn't exceed 242.5 lm/W total input energy if you stayed with an ideal white wide-band spectrum...

Come on, Torchboy... the word "electrical" creeps in because we are talking about devices that run purely on electrical power, obviously. A candle doesn't run on electricity. Please don't twist my words around. A candle's energy source is stored in its chemical composition, just like (for example) gasoline. Nobody's running around saying their car's efficiency is infinite, are they?

Hey, Kinnza - superb post! I am off to do my homework...

 

[TORCH_BOY]

Just when I got my Cree, its time to mod my lights again

 

[snakebite]

think about a panel full of these covered with a difuser installed behind your new 50" lcd tv display.

 

[Doug S]

Kinnza: A big thanks for the links to some excellent references. I may not have time to plow through all 101 pages of the one you have linked below but I am thinking that perhaps you meant to direct our attention to page 24 vs the 20 that you reference below.

In the page 20 of the 2001 OIDA roadmap
there is a example of a 399lm/w RGB spectra with CRI=80.

 

[SemiMan]

Would it be asked too much to get this thread back to discussing the REBEL and not lumens per watt and theoretical limits which I am sure has been discussed a hundred times on this board? Where is a moderator when you need one.... ;-)

 

[EngineeringGuy]

Just an FYI... the 80 lumen parts are "out there". Though they may not be abvailable unless you have enough clout with Future to get them. Plus you have to buy them by the reel (1000 pcs). I don't have them yet, but soon I will. Before anyone asks, no I can't sell any. My company is using them for R&D purposes. I will post any output figures I measure in our calibrated 1m integrating sphere though.

 

[metalhed]

Would it be asked too much to get this thread back to discussing the REBEL and not lumens per watt and theoretical limits which I am sure has been discussed a hundred times on this board? Where is a moderator when you need one.... ;-)

I'll try...

I received and posted this press release today. Not much real info, but apparently Quantum Lighting of Malaysia thinks that the new Rebel is suitable for portable lighting applications like flashlights.

Quantum Lighting to Introduce Lumileds Rebel-Powered Flashlights and Headlights

I don't have any product photos yet, but I'll try to follow up with Quantum and see if I can get an image or three to share...may have to wait until after the debut at the trade show first, tho'.

 

[TorchBoy]

Come on, Torchboy... the word "electrical" creeps in because we are talking about devices that run purely on electrical power, obviously. A candle doesn't run on electricity. Please don't twist my words around. A candle's energy source is stored in its chemical composition, just like (for example) gasoline. Nobody's running around saying their car's efficiency is infinite, are they?

Would it be asked too much to get this thread back to discussing the REBEL and not lumens per watt and theoretical limits which I am sure has been discussed a hundred times on this board? Where is a moderator when you need one.... ;-)

Yes, I acknowledge the Rebel, like all present-day production LEDs, produces its light entirely from electrical energy. But I also acknowledge that electricity is not the only way to produce light, or drive around. :lolsign:

 

[Brlux]

I have been playing with some Luxeon Rebels and thought I would share my thoughts and observations.



I was initially thinking of waiting till mid summer for the neutral white's to come out as I don't much care for bluish LED's. But curiosity got to me and I decided to go ahead and order some cool whites to play around with. I am very impressed with the tint of the cool whites. They are not the nasty blue that I was expecting but instead the tint is actually about what I was expecting the neutral whites to be. I am now even more curious to see how the neutral whites come out. The LED dome is not a hard epoxy like the other Luxeon products but it is not as soft as the SSC P4's and it doesn't seem to attract dust and lint like the SSC P4's do.



I was able to do some basic hand soldering of them for my initial testing and playing around. I took a piece of copper sheet pre tined the spot on the sheet and the back of the Rebel and then using some tweezers I was able to place the Rebel after I had heated up the copper sheet with the soldering iron next to where I was placed the Rebel. I placed it so that it was half way hanging off the copper sheet and then I was able to solder small wires to the + - pads. I have also laid out some PC boards and had great success with the toaster oven method and solder paste.



While they may not fit very well into the segment of the CPF community that likes to mod and upgrade their existing flashlights, I think they will serve other very useful purposes like home/structural lighting and who knows maybe we will wet see a flashlight or two use this LED.

 

[moon lander]

I have been playing with some Luxeon Rebels and thought I would share my thoughts and observations.



I was initially thinking of waiting till mid summer for the neutral white's to come out as I don't much care for bluish LED's. But curiosity got to me and I decided to go ahead and order some cool whites to play around with. I am very impressed with the tint of the cool whites. They are not the nasty blue that I was expecting but instead the tint is actually about what I was expecting the neutral whites to be. I am now even more curious to see how the neutral whites come out. The LED dome is not a hard epoxy like the other Luxeon products but it is not as soft as the SSC P4's and it doesn't seem to attract dust and lint like the SSC P4's do.



I was able to do some basic hand soldering of them for my initial testing and playing around. I took a piece of copper sheet pre tined the spot on the sheet and the back of the Rebel and then using some tweezers I was able to place the Rebel after I had heated up the copper sheet with the soldering iron next to where I was placed the Rebel. I placed it so that it was half way hanging off the copper sheet and then I was able to solder small wires to the + - pads. I have also laid out some PC boards and had great success with the toaster oven method and solder paste.



While they may not fit very well into the segment of the CPF community that likes to mod and upgrade their existing flashlights, I think they will serve other very useful purposes like home/structural lighting and who knows maybe we will wet see a flashlight or two use this LED.

you were able to hand solder these? please tell us more! did it require special tools? did you destroy any in the process? i think reflow soldering is what is keeping most of us from buying a bunch of them. at $2 each for 95 lumens, this is a hell of a deal. the reason i like them isnt size, its lumens per dollar.

 

[Brlux]

The hand soldering was just as described I heated up a Copper sheet with the soldering iron, once it was hot enough to melt the solder in the pre tined location I placed the side of the LED with the heat pad (pre tined) on the copper sheet. It was not an ideal setup for using the led, a 1" square copper sheet with a very small led halfway hanging off. But it is easily doable with moderate soldering skills and equipment and alows you to be able to experiment with and try them out. I like them and think they are great for LED area lighting due to the incredable lumen per dollar value.

 

[Robocop]

After reading many searched threads on CPF it seems the general opinion of this Rebel design is not what we were hoping for. It appears that this is better for area lighting such as landscape or home lighting applications...is this the general opinion ??

If it is designed for other applications it makes me curious as to where Lumileds makes most of their profits from.....does anyone care to guess if they are more involved in handheld flashlights or do they actually cater more to area or landscape lighting?

For a very long time I was not even aware of any other players in the game and thought Lumileds made the only luxeons available.....It seems to me that they simply may have been caught by suprise and rushed to get something out to get them noticed again......having said that I am curious if they intended for this new Rebel to be used in flashlights. It seems like to me that maybe this new emitter was not even intended for the CPF crowd and if it was they seem to have failed to impress many of us with first impressions.

 

[yellow]

It seems to me that they simply may have been caught by suprise and rushed to get something out to get them noticed again

+1 on that.
Seems to me (I dislike the rebel and its before and after marketing claims), that already happened with the K2 and never stopped from then on.

I would really like to see a sheet with the "intended" application.
Something where placing, soldering and at the same time fixing the slug to a heatsink is shown.

 

[kanarie]

-1 on that :
The Rebel is meant for a total different market (LCD displays etc.)

 

[SemiMan]

+1 on that.
Seems to me (I dislike the rebel and its before and after marketing claims), that already happened with the K2 and never stopped from then on.

I would really like to see a sheet with the "intended" application.
Something where placing, soldering and at the same time fixing the slug to a heatsink is shown.

For modern high volume production, the REBEL is probably the easiest part on the market to use. Pain in the *** to hand prototype, but that does not drive the market. It would be very easy to mount these on a small metal core board.

The intended application is anywhere you need cheap LED lumens from what I can tell. The package is not a detriment to any one making anything in volume.