Abstract
This investigation demonstrates a novel light-emitting
system with an array of blue light-emitting diodes (LEDs).
Unlike a conventional lighting system that is constructed from
white LEDs, the proposed planar lighting system uses blue LEDs
to excite a YAG : Ce<sup>3+</sup> yellow phosphor film remotely, yielding
a high lumen efficiency with uniform and planar light-emission.
The phosphor film herein acts as a wavelength converter and a
light diffuser simultaneously. The optical properties of the proposed
lighting system, angular color deviation and light-emitting
uniformity, are studied. Eventually, a high lumen efficiency (73.0
lm/W) and thin lighting module (7.5 mm-thick) was demonstrated
without the use of any conventional diffuser plate or light guiding
plate (LGP). A low color deviation (Δ<i>u'</i><i>v'</i>=0.025) and a high
light-emitting uniformity (U<sub>niformity</sub>=82% were achieved.
Hence, the proposed lighting system exhibited superior optical
performance using a compact module.
Index Terms—Angular color deviation, indium gallium
nitride (InGaN), light-emitting diodes (LEDs), phosphor, remote
phosphor, yttrium aluminum garnet (YAG).
© 2011 IEEE
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