New Investigation of the Subjective Glare Effect of Projection Type Headlamps

The goal of the investigations was to find out if there is a correlation between the luminance distribution on the lens surface of projection type headlamps (e.g. maximum luminance) and the average subjective glare rating (discomfort glare) of subjects under night time traffic conditions.

The luminance distributions of different projection type systems are measured with a luminance measurement system and compared concerning their characteristics.

For the validation a glare rating experiment has been carried out with a standard type glare source of different size and luminance peaks similar to projection lens luminances.

It was found out that for glare peaks up to a diameter of α = 2′ (observation angle) the candle power of the glare source is the proper parameter to calculate the subjective glare effect. For larger sizes of the glare sources there is a dependency to the diameter of the glare source for the glare effect. So it depends on the luminance distribution of the light emitting area if the candle power of the glare source is the right parameter to describe the glare effect.