Modelling of multichip LED packages for illumination

Abstract

Modelling of the spatial uniformity of the light output from multicolour light emitting diode (LED)-based lamps can be used to evaluate and optimize LED and reflector configurations. The percentage of the output beam that meets or exceeds a user-selected colour accuracy threshold is used as a figure of merit to compare lamp configurations. Results are presented for various distributions of red, green and blue (RGB) or red, amber, green and blue (RAGB) LEDs in a 4 × 4 square matrix. In general, the distributions with highest (4-fold rotational) symmetry have the most uniform output beams. However, those with least uniformity also have 4- fold symmetry, which indicates the importance of choosing the chip layout carefully. The colour uniformity for RAGB configurations is, in general, higher than the colour uniformity for RGB configurations. The colour uniformity at a correlated colour temperature (CCT) of 7000 K is generally higher than the colour uniformity at 3500 K for the LED spectral characteristics investigated.