Design and analysis of reflectors for non-lambertian light-emitting diodes

Abstract

A general reflector design method for light-emitting diodes (LEDs) with non-lambertian luminous intensity distributions is developed in this study. Curve fitting method was employed to get the mathematical expressions of the luminous intensity distributions of non-lambertian LED light sources and the optimal apertures of the reflectors for both uniform lighting and general lighting were obtained by energy conservation law and numerical method. Three types of LEDs manufactured by Cree®, which have different viewing angles, were employed to validate the method developed in this work. The simulation results show that the LED with a larger viewing angle can achieve a more compact reflector size and a larger optimal aperture than the LED with a smaller viewing angle for both uniform lighting and general lighting; furthermore, it can provide a wider lighting area. The uniformities of the three LED reflectors are better than 80% for the case of uniform lighting and better than 70% for general lighting.