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Cause of LED Efficiency Droop Finally Revealed
An anonymous reader writes "Researchers from the University of California, Santa Barbara, in collaboration with colleagues at the École Polytechnique in France, have been able to prove the theory behind LED 'droop.' LED droop is the term for how LEDs emit less light when the amount of current being pushed through them goes above a certain level. 'The cost per lumen of LEDs has held the technology back as a viable replacement for incandescent bulbs for all-purpose commercial and residential lighting.' Now that we understand what causes this, we should start to see research go into technology to circumvent LED Droop. 'LEDs have enormous potential for providing long-lived high quality efficient sources of lighting for residential and commercial applications. The U.S. Department of Energy recently estimated that the widespread replacement of incandescent and fluorescent lights by LEDs in the U.S. could save electricity equal to the total output of fifty 1 GW power plants.'"
A pre-print of the team's paper is available at the arXiv.
Or toxins, or radio waves, or autism that LEDs cause?
>the total output of fifty 1 GW power plants
Soooo... 50 GW?
Climate Progress - Hell and High Water
Well, at least after I replace them the first time.
Brain wandering time: If these are the kinds of lights we'll be putting in long duration spacecraft, it would make sense that they last at least a few decades, since it's cost prohibitive to bring supplies and, if we're talking about Mars, that's potentially a permanent installation (precluding "lunar module" style landers meant to take off later).
If computers were people, I'd be a misanthrope.
Over here in sweden it's hard to find a good old light bulb that will dim. But I guess I can live with the non dimming led bulbs for now
Anveto
Yo, genius, you misread the resistor markings when you wired up your Arduino circuit.
It's because of Auger recombination. Basically, you stick in too many electrons, and they all mill around talking with each other instead of getting any work done. This is also known as the 'Water Cooler Effect'.
Of course we would. We all have time machines.
It links to an .edu, ieee, and arxiv. It is not an advertisement, troll
Climate Progress - Hell and High Water
The ability of marketers to convince people to overpay for absolute garbage, is eclipsed only by people willing to work for peanuts in the middle of the night when they should be sleeping.
Leave to our government to have a Department of Energy Energy Frontier Research Center. This just in from the Department of Redundancy Department we can reduce half the E from the DOE EFRC using LED's to become LEED certified says the CEEM.
The little blue LEDs help me when I start to droop. Call your doctor if you don't stop drooping for more than two hours.
Is it me, or is the output color of household LED bulbs disgusting.
I've seen many different ones, and for some reason or another, to me they seem harsh on my eyes.
The incandescent ones seem warmer and friendlier to me.
Don't get me wrong, I'm no luddite. I'm all for saving energy, the environment, and stopping the flow of money to a55h0le muslim countries.
Does anyone else feel this way?
-HasHie @ irc.trypnet.net
Pay very close attention to LEDs. Now that we've identified the root cause of one of our biggest problems, in a few years, we'll find ways to work around those problems and extend the lifespan of an LED (and output at higher drive currents) with a minimal loss of light.
This is EXCITING news, as the uses for this across the entire electronics industry are MASSIVE. Higher-efficiency, longer-lasting LEDs means better optical devices and such, as this same tech can be applied down into solid-state laser diodes.
I'm literally about to piss myself from this news. The sheer implications of this knowledge are astounding.
I hope thermal pad and PCB makers are paying attention and prepare, because very soon we'll be pushing a LOT more power through these tiny LEDs, and we'll need the local cooling to compensate.
I only wonder just how far they can defeat or mitigate this effect, and how. Thicker well walls might be an idea, or perhaps a nano-wire-like growth pattern, like we've seen with the recent development of microwires on graphite sheets, can increase the surface area and reduce the available recombination area, thus forcing electron transport.
Something to either attract, guide, or force more electrons across the gap seems to be what is needed.
Still waiting on Serviscope_minor to wake up to fucking reality and realize that Jessica Price isn't going to fuck him.
Basically, past a threshold current, it starts to emit electrons instead of more photons (look up "auger effect").
Thanks again to "editors", illiterate both in English and science.
Fuck systemd. Fuck Redhat. Fuck Soylent, too. Wait, scratch the last one.
I'm literally about to piss myself from this news.
That's great, this is why I come here. What other site can you visit where people are more excited about a group of electrons than cute cats?
I'll bet right now you'd rather experiment with electrons than with sex.
"First they came for the slanderers and i said nothing."
I got to play with some on the market now ceramic heatsinks that went though a reflow oven (~260c) and was able to be handled no problem the second it comes out (something you usually want to wear gloves for)
It's ok, you don't need to brag about it.
"First they came for the slanderers and i said nothing."
It might include a crate.........
"First they came for the slanderers and i said nothing."
That 'ceramic' is still aluminum. Aluminum nitride and alumina mix, to be more precise
Still waiting on Serviscope_minor to wake up to fucking reality and realize that Jessica Price isn't going to fuck him.
Please be specific.
Do both - The Polecats - Make a circuit with me http://www.youtube.com/watch?v=YEfNjozD1BQ
"We were just stepping out to grab a bite to eat," said one LED, who asked that he remain anonymous. "We didn't realize anybody could see a difference. Terribly sorry."
William of Ockham had no beard. The most likely explanation is that it was chewed off by squirrels every morning.
The cost per lumen of LEDs has held the technology back as a viable replacement for incandescent bulbs for all-purpose commercial and residential lighting.
Really? CREE started distributing LED bulbs a month or two ago through Home Depot for less than $10 each. I own two of them.
450 lumens for $9.97 is 0.0222 per lumen. It's rated to last 22.8 years. That's $0.0010 per lumen per year of use.
Let's compare that to an "equivalent" (the cree is a 40-watt equivalent bulb) incandescent bulb. $8.77 for a pack of 6 is $1.46 per bulb.
300 lumens for $1.46 is $0.0049 per lumen. But it's only rated to last 0.9 years. That's $0.0544 per lumen per year of use. It's more than 54 times more expensive than the CREE. That's before you look at the electricity you'll be saving (6 watts to get more light than you would out of a 40 watt incandescent).
Home Depot is also selling CREE's 60-watt equivalent:
800 lumens for $12.97 is 0.0162 per lumen.It's rated to last 22.8 years. That's $0.0007 per lumen per year of use. The incandescent is 77 times more expensive.
As much as I love CREE LEDs in general, I prefer Philips 10.5-watt bulb. The bulb itself it more aesthetically pleasing (in my opinion) and it diffuses the light better (the CREE focuses all the bulbs in one area and its very apparent from the very bright spot in the middle). I own six of them. Home Depot sells them for $27.97 for a two pack.
800 lumens for $13.99 is $0.0175 per lumen. Rated to last 18.3 years. That's $0.0010 per lumen per year of use. If I'm going to spent the next two decades with a bulb, I'll spend the extra three hundredths of a cent per lumen on something I really like. Still less than one fiftieth the cost of an incandescent per lumen.
The only things I see holding back LED bulbs are misinformation and lack of availability (Home Depot is the only major brick and mortar store I've found that carries them). That, and some freaky designs that don't look like light bulbs... I bought one of these out of curiosity, and its appearance, on or off, just irritates me for some reason... if I was redesigning my living room to look like Quark's, I'd go with these all the way, but since I'm not "that guy" it's in a lamp that I almost never use. Which means it will probably outlive me. It may even survive to the 24th century and end up in Quark's.
For some a lot of fun can be had in combined experiments with electrons and sex, but that falls in the category SM.
Well, I might have a way, but it only works on a semi spherical planet in a vacuum.
...that we won't.
/rant off
From the summary: "The U.S. Department of Energy recently estimated that the widespread replacement of incandescent and fluorescent lights by LEDs in the U.S. could save electricity equal to the total output of fifty 1 GW power plants."
Now, raise your hands, everybody who thinks we'll save energy. Nobody? OK, now raise your hands if you think what we'll actually do is use this as an excuse to leave the lights on 24/7, thereby expending the same or greater amount of energy, AND increasing light pollution as a handy bonus. Great, thanks. You can all put your hands down now.
Ever paid attention to how many businesses around you leave much or all of their outdoor lighting and signage on, all night? Multiply that nationally or globally, and you've almost certainly located a lot more energy waste than 50 measly power plants. And as a double win, you can get rid of all that waste without creating even more landfill-fodder in the process. Just persuade everybody to switch their lights off when their business is closed, by removing incentives for leaving them on (insurance), and adding incentives for turning them off (fines for closed businesses with the lights on, perhaps.)
The whole "criminals avoid your business when the lights are on" thing might hold true when only a few businesses leave their lights on, but when we all do... that's a theory that no longer holds true. It's just a waste of resources, and a major source of light pollution.
I'll bet right now you'd rather experiment with electrons than with sex.
I think that field has been thoroughly explored, with each discovery being meticulously documented and repeated and sold on DVD to other scientists for careful study.
Despite the poor prospects for making an original contribution I hear it is still a popular undergraduate course though.
const int one = 65536; (Silvermoon, Texture.cs)
SJW, n: "Someone I don't like, and by the way I'm a fuckwit" - AC
very soon we'll be pushing a LOT more power through these tiny LEDs, and we'll need the local cooling to compensate.
Are you sure? Better efficiency also means that you need less cooling, as more power is emitted via visible light rather than heat.
Yeah. Looks like my summary is crap, too.
TFS is a typical empty PR gibberish, but I went overboard dumping on soulskill. My bad, soulskill.
Fuck systemd. Fuck Redhat. Fuck Soylent, too. Wait, scratch the last one.
Have gnu, will travel.
I'm literally about to piss myself from this news.
I would have been more comfortable if that sentence was at the end of your post, rather than at the start.. it now leads to two possible conclusions:
1. You don't know what literal means, or
2. You now smell funny.
"" How about taking the safety labels off everything, and let the stupidity-problem solve itself? """
Good post, but I thought the main problem with getting decent LED light bulbs (for example) popular was the cost and that increasing the light produced too much heat. I for one would rather not see a fan-assisted bulb because of noise pollution. Do you think this discovery will help reduce heat to any degree for a given amount of lumens?
Why OpalCalc is the best Windows calc
I think you're on to something there. An improved Cathode might help the flow of electrons to the n-side. We just need a more attractive Cat.
I don't think phantomfive was being facetious or in any way sarcastic with his comment. Just us guys love technology/science so much that these things can *sometimes* become more exciting than some of our more carnal desires.
Why OpalCalc is the best Windows calc
If you believe that LED bulbs will really last 22.8 years, then there is a bridge I'd like to sell to you. The LED bulbs are only as good as the capacitors inside of them, and current electrolytics will not last 22.8 years at the 140 degF and higher temperatures LED bulbs run at. I seriously doubt that most LEDs would make it to the 7 year mark with regular use.
Where's your cost comparison with 75 watt or 100 watt equivalent replacements? You conveniently left those out as those are typically twice as expensive as 60 watt equivalent replacements. These higher wattage lamps are also pushing the thermal limits even more, so lifespan will be even shorter.
Only pay extra for LEDs if you want increased light quality, but a 22.8 year investment it is not As it stands now, I'd expect a lifespan only slightly higher than that of a CFL.
.edu's put out press releases all the time as a form of advertisement.
Public relations and marketing isn't just about selling the product, it's about creating the demand.
So they may not be trying to sell you something, but they're definitely trying to drum up prestige
and, if they're lucky, they'll get funding for more research or good press for licenseable technology.
The world of academics is money driven, just like any other industry.
[Fuck Beta]
o0t!
This has little to do with efficiency. This has to deal with output versus input, and a barrier that's present whenever current gets too high, causing drastic loss of light and lifespan of the LED.
This might push higher efficiency but the issue we're solving RIGHT NOW is why we suddenly lose a ton of light output once we hit a certain threshold.
That still doesn't change the fact these LEDs get very hot locally (and in high-power packages, like the MK-R or XP-G) without that thermal consideration, your diodes are dead in a couple of days. The thermal cooling required will increase as power levels increase.
Still waiting on Serviscope_minor to wake up to fucking reality and realize that Jessica Price isn't going to fuck him.
Spoken like a true ignorant AC.
Best CCFL is ~80 lumens per watt, 6500K CCT.
Best LED is 200+ lumens per watt, and it cost me NOTHING to get several of them, with mounting boards, in my hands.
Or, I just buy them from China, where a 4w GU-10 using Epistar 130+ lumen per watt LEDs costs me 4 bucks and has lasted me several years already.
Go home with your ignorant tripe.
Still waiting on Serviscope_minor to wake up to fucking reality and realize that Jessica Price isn't going to fuck him.
"I thought the main problem with getting decent LED light bulbs (for example) popular was the cost and that increasing the light produced too much heat."
The only issue with cost comes from name-brand companies that foolishly spent a lot of money patenting something OBVIOUS. In the meanwhile, China pumps out obvious, unpatentable designs, and sells them for cheap. And they're quality. Out of thousands of bought and used LED panels, light bulbs, laser diodes, only a couple total have failed on me, and the ones that did fail were EASILY repairable by the end-user. Increasing power always means increasing heat, that's just thermodynamics.
"I for one would rather not see a fan-assisted bulb because of noise pollution"
Given the requirement to fit certain form factors, we're not left with much of a choice. 12w passive LED has a heat sink roughly the size of a PAR30 floodlight. With a fan actively cooling, you can fit it inside a standard ceiling fan socket. I prefer active cooling anyways, as if you have bad airflow in your house, you're going to likely kill the LEDs with heat since the passive radiator isn't getting proper airflow.
"Do you think this discovery will help reduce heat to any degree for a given amount of lumens?"
At higher drive currents, yes. At our typical lower drive currents, likely not, as the efficiency there lies mostly in the composition and physical structure of the wafer/substrate.
Still waiting on Serviscope_minor to wake up to fucking reality and realize that Jessica Price isn't going to fuck him.
I'll bet right now you'd rather experiment with electrons than with sex.
Why not both?
Better efficiency at higher current means that the tradeoffs involved in LED fixture design are optimized with a smaller number of LEDs. Price will go down, waste heat might go down.
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Cree's profit margin is below 5% and its officers are not extravagantly paid. I've seen no evidence that they're not an honorable company.
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So THAT'S why colleges have such a left wing bias.
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