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Proceedings Paper

Performance characteristics of high-power light-emitting diodes
Author(s): Nadarajah Narendran; Lei Deng; Richard M. Pysar; Yimin Gu; Hua Yu
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Paper Abstract

A laboratory experiment was conducted to investigate the performance characteristics of the currently available high-power LEDs under various drive conditions and ambient temperatures. Light output degradation and color shift properties as a function of time were measured for five types of commercial high-flux LEDs, namely, red, green, blue, and white from one manufacturer, and a different high-flux white LED package from a second manufacturer. The major difference between the two manufacturers’ products is that the first uses a single LED die per package, and the second uses multiple dies within its package. LED arrays were tested under normal drive current and ambient temperature, normal drive current and higher ambient temperature, and higher drive current and normal ambient temperature. Because each LED type has to operate at a particular ambient temperature, all were tested in specially designed individual life-test chambers. These test chambers had two functions: one, to keep the ambient temperature constant, and two, to act as light-integrating boxes for measuring light output parameters. Overall, the single-die green and white LED arrays showed very little light loss after 2,000 hours, even though the current and the ambient temperature were increased. However, the red LED array seemed to have a high degradation rate. The white LEDs had a significant color variation (of the order of a 12-step MacAdam ellipse) between them. However, the color shift over time was very small during the initial 2,000-hour period. For white LEDs to be accepted broadly for general illumination applications, the color variation between similar products must become much smaller, of the order of a 2-step MacAdam ellipse.

Paper Details

Date Published: 26 January 2004
PDF: 9 pages
Proc. SPIE 5187, Third International Conference on Solid State Lighting, (26 January 2004); doi: 10.1117/12.515647
Show Author Affiliations
Nadarajah Narendran, Rensselaer Polytechnic Institute (United States)
Lei Deng, Rensselaer Polytechnic Institute (United States)
Richard M. Pysar, Rensselaer Polytechnic Institute (United States)
Yimin Gu, Rensselaer Polytechnic Institute (United States)
Hua Yu, Rensselaer Polytechnic Institute (United States)


Published in SPIE Proceedings Vol. 5187:
Third International Conference on Solid State Lighting
Ian T. Ferguson; Nadarajah Narendran; Steven P. DenBaars; John C. Carrano, Editor(s)

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