Factors affecting the dependence of the visible range of headlamps of different beam patterns are considered. Projection and reflection systems fitted with halogen bulbs were investigated in a light testing facility. Subjective impressions of visible range depended on the beam pattern and the level of illuminance. Vertical illuminance as a criterion for recognisability distance was investigated. The deviations of one third of all beam patterns examined indicated that the 2 lx line cannot be regarded as the generally valid threshold of recognition. Contrast as a criterion for visible range is discussed. Average edge contrast is considered a safe threshold criterion for the determination of visible range even for different beam patterns. For the covering abstract see ITRD E123380.
Samenvatting