LED L Prize bulbs show miniscule degradation after 25,000 hours
Washington, DC--The U.S. Department of Energy (DOE) reports that the light-emitting diode (LED) lamp from Philips Lighting North America that won the L Prize in the 60 W replacement category has shown no falloff in light output after 25,000 hours of continuous lumen maintenance testing (http://www.lightingprize.org/60watttest.stm).
When the prize was awarded in August 2011, DOE predicted the Philips lamp would achieve lumen maintenance (http://www.laserfocusworld.com/articles/2010/01/light-illumination-innovation-in-leds-has-plenty-of-runway-to-go.html) of 97.1% at 25,000 hours, based on the 7,000 hours of testing that 200 samples had already undergone in a specially constructed high-temperature (45° C) facility. Even though this far exceeded the competition’s 70% requirement, DOE’s intention was to continue testing the lamp for an extended period.
When 25,000 hours of operation was reached on April 29 of this year, none of the lamps had failed, and the average lumen maintenance of the samples was 100% of the initial output. What's more, the color was stable, with the chromaticity change on the International Commission on Illumination (CIE) 1976 color diagram found to be less than 0.002 after 25,000 hours—well within the competition's tolerance of 0.004 at 7,000 hours of operation. These results show that well-designed LED integral lamps (http://www.strategies-u.com/articles/reports/market-for-high-brightness-leds-in-lighting-applications-2013.html) can operate very reliably over long periods of time, with excellent lumen and chromaticity maintenance.
To learn more, download the updated report (http://www.lightingprize.org/pdfs/lprize_60w-lumen-maint-testing.pdf) on lumen maintenance testing of the Philips 60W L Prize entry.
SOURCE: U.S. Department of Energy; http://www1.eere.energy.gov/buildings/ssl/
Gail Overton | Senior Editor (2004-2020)
Gail has more than 30 years of engineering, marketing, product management, and editorial experience in the photonics and optical communications industry. Before joining the staff at Laser Focus World in 2004, she held many product management and product marketing roles in the fiber-optics industry, most notably at Hughes (El Segundo, CA), GTE Labs (Waltham, MA), Corning (Corning, NY), Photon Kinetics (Beaverton, OR), and Newport Corporation (Irvine, CA). During her marketing career, Gail published articles in WDM Solutions and Sensors magazine and traveled internationally to conduct product and sales training. Gail received her BS degree in physics, with an emphasis in optics, from San Diego State University in San Diego, CA in May 1986.