Paper
21 June 2004 Highly efficient UV-based conversion LEDs for the generation of saturated colors with improved eye safety
Bert Braune, Herbert Brunner
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Abstract
Recently near UV conversion LEDs with an excitation wavelength of around 400nm have attracted increasing interest due to their high efficiency and output power. Favorably is also the great variety of efficient phosphors available for near UV excitation. For the generation of saturated colors this method is very efficient especially for dominant wavelengths from 480 nm to 570 nm. Direct light emission from InGaN chips show a strong temperature and current dependency increasing with the emission wavelength and may cause disturbing color shifts in applications. For the wavelength range between 530 nm to 570 nm the physical limitations of the InGaN system are reached and the efficiency of the InGaAlP system is not yet satisfying. Conversion LED's based on near UV-light emitting chips provide solutions for both problems. But up to now a disadvantage of these LEDs is the residual near UV-light emission which could lead to severe eye damages over time. OSRAM OS developed a eye safe solution by avoiding the near UV-peak while maintaining the high luminous efficiency. A luminous efficiency of 28 lm/W for λdom of approx. 560 nm was demonstrated, a value more than ten times higher than the efficiency of green emitting InGaAlP diodes. For these LEDs no more restrictions because of eye safety regulations are expected.
© (2004) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Bert Braune and Herbert Brunner "Highly efficient UV-based conversion LEDs for the generation of saturated colors with improved eye safety", Proc. SPIE 5366, Light-Emitting Diodes: Research, Manufacturing, and Applications VIII, (21 June 2004); https://doi.org/10.1117/12.530295
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KEYWORDS
Light emitting diodes

Near ultraviolet

Eye

Absorption

Transparency

Ultraviolet radiation

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