Abstract
A white light source using direct phosphor-conversion excited by a blue laser diode is presented. In this preliminary study we have investigated the influence of phosphor’s thickness and operating current of the laser diode over the (x, y) chromaticity coordinates, Correlated Color Temperature (CCT) and Color Rendering Index (CRI). The best values found were 4000 K and 94. A 40 lm/W luminous efficacy was achieved together with a CRI close to 90 for an operating current of 0.8 A. Those values, to the best of our knowledge, were not previously reported in the literature.
Highlights
Creating a more efficient white light source is a challenge since several years
In this preliminary study we have investigated the influence of phosphor’s thickness and operating current of the laser diode over the (x, y) chromaticity coordinates, Correlated Color Temperature (CCT) and Color Rendering Index (CRI)
Liu et al.[2] have focused on improving the luminous flux emitted by a light emitting diodes (LED); Yang et al.[3] used a blue LED with two phosphors: the mixing of the LED direct emission with the two luminous band converted by the phosphors resulted in a white light with a CRI of 90, a CCT of 5200 K and a luminous efficiency of 30 lm/W
Summary
Creating a more efficient white light source is a challenge since several years. Solid-state lighting (SSL) gained wide interest since the development of white light emitting diodes (LED) by Nakamura et al.[1]. Liu et al.[2] have focused on improving the luminous flux emitted by a LED; Yang et al.[3] used a blue LED with two phosphors (green and red): the mixing of the LED direct emission with the two luminous band converted by the phosphors resulted in a white light with a CRI of 90, a CCT of 5200 K and a luminous efficiency of 30 lm/W. This was achieved at a 20 mA DC current level for the LED. This counteract the production of more photons per unit area of the LED chip, making therefor SSL less affordable
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