RECENT STEPS TOWARD INTERNATIONAL HARMONIZATION OF THE LOW-BEAM HEADLAMP PATTERN

Inherent in the design of a low-beam (passing-beam) headlamp pattern i s a trade-off between providing sufficient seeing for the driver using the headlamp and protecting oncoming drivers from glare. There are di fferences between the US and European approaches to this trade-off, st emming from a greater emphasis in Europe on protecting oncoming driver s from glare and on the ease of aiming the headlamp beam visually. Bec ause neither approach appears to be superior overall in terms of visua l performance, there is a strong economic impetus to develop a harmoni zed (common) beam pattern. This article summarizes two recent studies related to the issue of harmonization of beam patterns, and describes the current state of the harmonization efforts. The first of the two s tudies evaluated several current and proposed standards for low-beam h eadlamp patterns. The second study generated a proposal for partial ha rmonization, by recommending a small number (four) of the most importa nt test points and their accompanying photometric limits. A slightly m odified version of these four test points is currently being considere d by international regulatory agencies for incorporation into existing standards.