This paper presents a new method to describe headlamp light distributions by taking into account visible performance, measurable lighting parameters and physiological comfort aspects. Up to now, headlamp light distributions have been evaluated by looking to photometric measurements, which are displayed as isolux or isocandela values. Based on investigations intended to examine the driver's basic requirements for a good light distribution, the resulting measurement tools are split into two sections to describe the performance: safety and comfort. For both sections, the tools are described and demonstrated with two light distributions that show different behaviour. The safety evaluation tools are defined and presented. For the comfort of driving, the light distribution generated on the street concerning luminance, contrast sensitivity and homogeneity are further parameters. A new possibility of defining a single quality parameter for the homogeneity is given. Two different headlamp light distributions are compared and evaluated by means of the developed tools. (A)
Abstract