4 ms·

Yes, it has been tested. The industry standar LM-80 lifetime testing of the LED shows an L70 lifetime of ~300,000 hours. We are operating the LEDs at a lower te

Yes, it has been tested. The industry standar LM-80 lifetime testing of the LED shows an L70 lifetime of ~300,000 hours. We are operating the LEDs at a lower temperature meaning they should theoretically last even longer. This is how we specify the 96,000 hour operating time to 90% The Royal Blue LEDs we use have a ~55% EQE (external quantum efficiency). This gives a μmoles per joule a fair amount above 2.0. We lose a few photons during the conversion process and that drops us down to about 2.0. We have a ~30% efficiency improvement over standard white LEDs because the phosphor is remote. The gain is 100% due to to the recycling cavity and omnidirectional nature of phosphors.

ewang1 11y ago
The LM80 will show a much higher number, but in reality, it's usually the drivers that fail much sooner.
nkurz 11y ago
I'm still surprised at the level of efficiency, but glad to hear that you can back it up. I wasn't doubting that an underdriven LED would last that long, rather I was surprised that the remote phosphors would last that long without decrease in output. But reading more elsewhere, I now see that the lifespan of the remote phosphors can be excellent: http://www.digikey.com/en/articles/techzone/2014/apr/developing-a-standard-test-for-remote-phosphor-lifetime-and-color-maintenance http://www.digikey.com/en/articles/techzone/2014/apr/develop... For others who are interested, here's another interesting link on the remote phosphor approach: http://www.ledsmagazine.com/articles/print/volume-9/issue-7/features/fair-comparison-of-white-leds-and-remote-phosphor-guides-design-choice-magazine.html http://www.ledsmagazine.com/articles/print/volume-9/issue-7/... And a nice overview of the efficiencies of white LED's, and where the losses usually are: http://www.sandia.gov/~jytsao/SSL_Trajectories_Proc_IEEE.pdf http://www.sandia.gov/~jytsao/SSL_Trajectories_Proc_IEEE.pdf The exact figure in the last are already somewhat out of date, but if you plug in the specs for the newer LED's, presumably the underlying physics hasn't changed.

ewang1 11y ago

The LM80 will show a much higher number, but in reality, it's usually the drivers that fail much sooner.

nkurz 11y ago

I'm still surprised at the level of efficiency, but glad to hear that you can back it up. I wasn't doubting that an underdriven LED would last that long, rather I was surprised that the remote phosphors would last that long without decrease in output. But reading more elsewhere, I now see that the lifespan of the remote phosphors can be excellent: http://www.digikey.com/en/articles/techzone/2014/apr/developing-a-standard-test-for-remote-phosphor-lifetime-and-color-maintenance http://www.digikey.com/en/articles/techzone/2014/apr/develop... For others who are interested, here's another interesting link on the remote phosphor approach: http://www.ledsmagazine.com/articles/print/volume-9/issue-7/features/fair-comparison-of-white-leds-and-remote-phosphor-guides-design-choice-magazine.html http://www.ledsmagazine.com/articles/print/volume-9/issue-7/... And a nice overview of the efficiencies of white LED's, and where the losses usually are: http://www.sandia.gov/~jytsao/SSL_Trajectories_Proc_IEEE.pdf http://www.sandia.gov/~jytsao/SSL_Trajectories_Proc_IEEE.pdf The exact figure in the last are already somewhat out of date, but if you plug in the specs for the newer LED's, presumably the underlying physics hasn't changed.