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| | Cree reports R&D result of 231 lm/W efficacy for white LED | | 10 May 2011 | | Cree has extended the efficacy record for a white LED tested at room temperature and 350 mA current.
| | LED manufacturer Cree, Inc. has claimed a new R&D record for power-LED efficacy of 231 lm/W. The value was measured for a single-die component at a correlated color temperature of 4500 K.
Standard room-temperature testing at 350 mA – i.e. pulsed testing rather than steady-state or “hot” testing – was used to achieve the results.
Cree described the result as “a significant advance beyond [our] previous industry record” of 208 lm/W efficacy for an R&D LED, which was reported in February 2010. The company also said the result “further demonstrates how Cree’s relentless innovation continues to push the boundaries of what is possible with LED lighting.”
“It wasn’t long ago when 200 lumens per watt was considered the theoretical maximum efficiency for a lighting-class LED. We broke that barrier in 2010, and have now achieved 231 lumens per watt,” said John Edmond, Cree co-founder and director of advanced optoelectronics.
“The innovation from our labs is the foundation for our industry-leading XLamp LED family and an invention that continues our leadership of the LED lighting revolution.”
Cree says that the results came from an R&D component that features advanced aspects of the same technology used in the company’s XLamp white LEDs. The same level of performance is not yet available in Cree’s production LEDs.
Cree says it believes higher-performance LEDs can enable new LED-based applications and drive down the solution cost of current LED-based designs.
| | About the Author | | Tim Whitaker is the Editor of LEDs Magazine. | | COMMENTS | | Name: rsailor Posted: Wed, 11 May 2011 20:05 |
| Ok, now what is the power conversion efficiency at this "efficacy"? | | Name: tonyyan Posted: Thu, 12 May 2011 08:05 |
| It is meaningless, as the efficiency is related about the color temperature, the color rendering index. Without this claim, the results are no sense to any lighting application.
| | Name: skynet Posted: Thu, 12 May 2011 15:05 |
| Cree's achivement of 231Lm/W for 4500K color temperatue is terific. If you are in lighting business, you would know that the current definition and measurement for color redition is CRI or Ra. Use value of CRI to belive how good the color rendering of the LED light is meaningness. A new approch to measure CRI is on going. I think this is why that Cree don't specify the CRI at this moment. We can use red, green, and blue LEDs combine togather to come out a perfect color rendering light, but when you measure it by current sphere-spectrodadiometer system, the reading could be 25 only.
Belive your eye, don't belive the value of CRI when you choose LED as a lighing source. | | Name: alzie Posted: Fri, 13 May 2011 04:05 |
I used to think that 240 lm/W would be 100% efficiency for pure white.
Maybe thats a little bit low, but hey: 231 lm/W is stupendous!
Imagine that, this LED is making more light than heat.
Maybe we can finally nail the coffin of vacuum / mercury technology.
And, the conservatives still want to keep their incandescents!
Now, if we can get PV technology up there too.
| | Name: morelite Posted: Thu, 19 May 2011 10:05 |
| We're getting there with the PV. An Austrian lighting company has a cylindrical solar module made of monocrystaline PV cells with a whopping 22% yield. Anything more than that and you're talking satellite grade PV. The best thing is that the panel is gone. LED and PV in a combination that is actually quite elegant. Administrators Reply Yield? Or conversion efficiency? | | Name: undertheradar Posted: Thu, 11 Aug 2011 18:08 |
| A green light at 555 nm has a maximum possible luminous efficacy of 683.002 lm/W to be 100% efficient. So these posts that indicate LED's are anywhere close to even producing more light than heat are incorrect. Even a "white" LED that is 300lm/W is still at 43.9% efficiency. The percentages dont add up since the photometric scale uses values that are weighted to reflect how the human eye sees light... most sensitive to green, then red, then less than 12% to blue. A radiometric value is a pure photon count and would reflect a higher efficiency for these higher Kelvin LED's, even though the human eye does not pick up blue light as well as red or green.
Anyways, I just wanted to add some clarity to what this efficiency in lumens per watt means as far as conversion of electricity to heat. |
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