Lumen Efficiency of 1 W2level High Power White LED

LI Bing2qian
(Dept.of Physics,Foshan University, Foshan 528000,CHN)
Abstract : 　The relationship of lumen efficiency with input power of high power white light2 emitting diodes (LEDs) is studied. The result shows that the lumen efficiency increases with input power in the range of 0～0.11W.At theinputpowerof0.11Wlumenefficiencyis15.6lm/
W. Then the lumen efficiency decreases with the increcse of input power over 0. 11 W ,and the decrease rate is more and more faster followed by the increase of the input power. At the rating power of 1 W , the lumen efficiency is close to 13 lm/ W. The main reasons which induced inefficiency of high power white light2emittingdiodesathighinputpowerare: (1) theincreaseof input power results in higher temperature of LED chip; (2) the increase of the current causes more leakage current.
Key words : 　high power white L ED ; semiconductor lighting source ; luminous flux ; lumen efficiency  www.bgocled.com