Optical design for a cost-effective low-beam headlamp with a white light LED

Abstract

We present a design for a cost-effective low-beam automotive headlamp with a single light-emitting diode (LED) light source. The proposed design consists of a white LED, an elliptical reflector, a parabolic reflector, a toric lens, a filter, and a prism array. The white LED had a luminous flux of 146 lm. Non-sequential rays were used to improve the efficiency and a toric lens was employed to optimize the light pattern on a 25 m screen which appeared as rectangular with a high degree of uniformity. In addition, the filter and the prism array were modified to correct the measured light pattern results to meet the requirements of ECE R112. We set the reflectivity of the elliptical and parabolic reflectors for the compound reflectors to be 95%. The transmittance of each surface of the toric lens is 98%. The total received lumens was 80.62 lm, and the overall efficiency was 55.22%.