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.

Color distribution from multicolor LED arrays

“…Other possible applications of this analytic technique include computation of: color rendering index distribution; and angular color distribution of multichip LEDs, which requires knowing the intensity distribution of each single chip [22].…”

“…where Δuv(x,y)] max or by the fraction of points where Δuv(x,y) value is below a specified threshold [22]. However, these merit functions present some limitations as a metric if the color pattern has a profile that contains large color deviations.…”

Differential evolution for the optimisation of multi-band white LED light sources

“…32 A further practical matter is the uniformity (or otherwise) of the colour in the mixed-LED light beam. 6 Thus, employing four (rather than more) LEDs is adopted for pragmatic reasons: i.e. simplifying the mixing process and the control of the white point, without sacrificing the beneficial characteristics of the white-light source.…”

“…1 With LEDs, white light can be produced either using blue light to irradiate a yellow-emitting phosphor, 2,3 or by combining the outputs of multiple narrowband LEDs. 1,[4][5][6][7] The latter approach may result in a white-light spectrum with higher radiant luminous efficiency than the former since there is no loss of energy due to downconversion. 5,8 Both approaches aim to design LED-based white-light sources characterised by high colour rendering and high luminous efficacy.…”