EE Times: LEDs poised to replace light bulbs

davidefromitaly

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wow!!!!!!!!!!

this meaning that a 5W led will output about 200 lumens without become hot?

our led flashlight will become obsolete in a few... /ubbthreads/images/graemlins/cool.gif
 

Reptilezs

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[ QUOTE ]
davidefromitaly said:
wow!!!!!!!!!!

this meaning that a 5W led will output about 200 lumens without become hot?

our led flashlight will become obsolete in a few... /ubbthreads/images/graemlins/cool.gif

[/ QUOTE ]
no it talks about a reflector being 99 percent efficient not the led being 99 percent efficient
 

PhotonWrangler

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[ QUOTE ]
idleprocess said:
RADIOS MAY BE PORTABLE BY 1950

[/ QUOTE ]

I'm still waiting for the moving sidewalks that they promised.
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NewBie

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the omni-directional mirror has been seen before, in several variations, here is one from Epistar Corporation, Hsinchu, Taiwan.

http://www.compoundsemiconductor.net/articles/magazine/9/12/4/1

What makes his different, is his 99% reflection. There are several folks already employing the technique, but not up at the 99% level.

Oriol is an example, who utilized several layers of reflecting metal in their Gigabright line. Not sure if they got their patent yet or not.

Someone even did a Bragg reflector based design:

The design, fabrication, and performance characteristics of a back-surface distributed Bragg reflector (DBR) enhanced InGaN/GaN light-emitting diode (LED) are described. A wide reflectance bandwidth in the blue and green wavelength regions is obtained using a double quarter-wave stack design composed of TiO2 and SiO2 layers. More than 65% enhancement in extracted light intensity is demonstrated for a blue LED measured at the chip level. Similar improvement in green LED performance is discussed and achieved through simulation. Possible applications of back-surface DBR-enhanced LEDs include surface-mount packages with significantly reduced vertical profiles, resonant cavity LEDs, and superluminescent diodes.
—Department of Electrical and Computer Engineering, University of California, Irvine, CA 92697.
—AXT Optoelectronics, Monterey Park, CA 91754.


Dec 8, 2002
A more compact, low profile solution that promises even higher extraction efficiency is to use a mirror deposited directly on the back surface of the chip. Additionally, this Dielectric multilayer mirrors can be designed to provide >99% reflectance over a relatively broad wavelength range, have negligible adsorption in the blue-green wavelength region, and exhibit good adhesion to sapphire.
 

jtr1962

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[ QUOTE ]
davidefromitaly said:
wow!!!!!!!!!!

this meaning that a 5W led will output about 200 lumens without become hot?


[/ QUOTE ]
Actually, if your 5W LED didn't become hot (meaning it was close to 100% efficient), it would output anywhere from 1000 to 2000 lumens, depending upon the spectrum, not 200 lumens.

If this concept can increase light extraction (and hence efficiency) by 65%, then it is certainly a breakthrough. Nichia's new LEDs get around 40 lm/W. Employing the new mirrors would bring that to ~65 lm/W even without any other process improvements. Cree demonstrated white LEDs with 74 lm/W efficiency. A 65% improvement here (to ~120 lm/W) would make them even more efficient than metal halide. If this can be applied easily and cheaply to current LED production, then I think this is just what the industry needs right now.
 

NikolaTesla

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How about the new q-dots at Los Alamos labs? They claim higher efficiency than LED's.

NikolaTesla /ubbthreads/images/graemlins/smile.gif

An Arc lamp is the Spark that takes away the Dark--HID Forever!

My Lights LightWar /ubbthreads/images/graemlins/xyxgun.gif
 

paulr

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I think a typical 100 watt household lightbulb is 1710 lumens and costs about $1. LED's may beat them on technical measures but have a long way to go before they catch up in cost per lumen, even if you count electricity costs.
 
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