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Proceedings Paper

Spectral and luminous efficacy change of high-power LEDs under different dimming methods
Author(s): Yimin Gu; Nadarajah Narendran; Tianming Dong; Huiying Wu
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Paper Abstract

Dimming is an important and necessary feature for light sources used in general lighting applications. An experimental study was conducted to quantify the spectral and luminous efficacy change of high-power colored and pc-white LEDs under continuous current reduction (CCR) and pulse-width modulation (PWM) dimming schemes. For InGaN-based blue, green, and pc-white LEDs, the peak wavelength shifts were in opposite directions for the two dimming schemes. The peak wavelength showed a blue shift with increased current, most likely due to band filling and QCSE dominated effects. InGaN LEDs exhibited red shifts with increased duty cycle, which is dominated by junction heat. AlInGaP red LEDs show mainly thermal-induced red shift with increased current or duty cycle. In addition, the luminous efficacy was always higher for the CCR dimming scheme at dimmed levels, irrespective of the LED type. Keywords: Light-emitting diodes (LEDs), white LEDs, mixed-color white LEDs, pulse-width modulation (PWM), continuous current reduction (CCR), peak wavelength shift, luminous efficacy

Paper Details

Date Published: 12 September 2006
PDF: 7 pages
Proc. SPIE 6337, Sixth International Conference on Solid State Lighting, 63370J (12 September 2006); doi: 10.1117/12.680531
Show Author Affiliations
Yimin Gu, Rensselaer Polytechnic Institute (United States)
Nadarajah Narendran, Rensselaer Polytechnic Institute (United States)
Tianming Dong, Rensselaer Polytechnic Institute (United States)
Huiying Wu, Rensselaer Polytechnic Institute (United States)

Published in SPIE Proceedings Vol. 6337:
Sixth International Conference on Solid State Lighting
Ian T. Ferguson; Nadarajah Narendran; Tsunemasa Taguchi; Ian E. Ashdown, Editor(s)

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