Headlamp beam-pattern shifts with thermoplastic complex reflectors: a comparison to shifts from other causes

Abstract

Traditional headlamps use functional lenses that focus or disperse the light. Thus, the optical control of traditional headlamps is achieved, to a large extent, by the lenses. In contrast, one of the new trends in automotive headlighting eliminates the need for functional lenses by incorporating the optics in the reflectors. However, thermal effects in headlamps with such reflectors have a greater influence on the location of the beam pattern than in headlamps with conventional reflectors, especially if the complex reflector is made of a thermoplastic material. A study by Serman et al. (1995) reported the vertical and horizontal beam-pattern shifts relative to shifts from other known causes. The analysis indicates that the shifts in the beam pattern associated with the use of thermoplastic complex reflectors of the magnitude reported by Serman et al (1995) will not appreciably change the current on-the-road misaim of low-beam headlamps in the United States.