Design of a high-efficiency system with combined reflectors for a light-emitting diode front fog lamp

Abstract

This paper provides a design method for a light-emitting diode front fog lamp system based on a freeform surface and an improved quadric surface. First, a light-receiving reflector is used to converge the light-emitting diode beam to form an equivalent lighting point. Then, the relationship between the point and the light pattern on the work surface is calculated, and the freeform surface is constructed based on Snell’s law and non-imaging optical theory. Finally, two compensated reflectors are added at both ends of the freeform surface to reflect the unutilized light to achieve the compensation effect. By application of combined reflectors, the light pattern at the work surface 25 m away can satisfy the requirement of ECE R19 Revision 7. Also, this system has the advantages of small size and high efficiency because lens or prism groups are avoided. And the utilization of a compensated surface also increases light efficiency. Finally, a prototype model is tested, which also meets the regulatory requirements.