DocumentCode :
1079980
Title :
Studies of Phosphor Concentration and Thickness for Phosphor-Based White Light-Emitting-Diodes
Author :
Tran, Nguyen T. ; Shi, Frank G.
Author_Institution :
Henry Samueli Sch. of Eng., Univ. of California, Irvine, CA
Volume :
26
Issue :
21
fYear :
2008
Firstpage :
3556
Lastpage :
3559
Abstract :
The dependence of luminous efficacy on phosphor concentration and thickness for high-power white light-emitting-diode (WLED) lamps is investigated by employing three-dimensional ray-tracing simulations. The simulations show that the brightness or luminous efficacy of WLED lamps highly depends on the combination of phosphor concentration and phosphor thickness (or phosphor-matrix composite volume). The package with lower concentration and higher phosphor thickness has higher luminous efficacy because the light trapping efficiency is lower with the low phosphor concentration. At the correlated color temperature (CCT) value of around 4000 K, ray-tracing simulation and experimental results show 20% and 23% improvement in lumen, respectively, with a 1.8-mm-phosphor package over a 0.8-mm-phosphor package. A package with convex lens can improve the lumen output over flat lens, but this improvement is small, and it requires higher amount of phosphor, up to 25%, to achieve same CCT value.
Keywords :
LED lamps; brightness; lenses; optical materials; phosphors; ray tracing; brightness; convex lens; correlated color temperature; light trapping efficiency; lumen output; luminous efficacy; phosphor concentration; phosphor thickness-based WLED lamps; phosphor-matrix composite volume; size 0.8 mm; size 1.8 mm; temperature 4000 K; three-dimensional ray-tracing simulation; white light-emitting-diodes; Geometry; Humans; Lenses; Light emitting diodes; Light scattering; Packaging; Particle scattering; Phosphors; Ray tracing; Temperature; LED; WLED; light emitting diodes; phosphor;
fLanguage :
English
Journal_Title :
Lightwave Technology, Journal of
Publisher :
ieee
ISSN :
0733-8724
Type :
jour
DOI :
10.1109/JLT.2008.917087
Filename :
4758641
Link To Document :
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