The photometrical performance of automotive headlamps is usually estimated from measurements in photometrical labs. Usually two kinds of tests are made. The first kind checks the fulfillment of the corresponding legal requirements regarding minimum or maximum illuminances on a test screen or intensities in given directions. The second kind involves a measurement of the light distributions in an angular area and graphical evaluation of isolux diagrams on test screens or other illuminated areas. Even with modern methods of graphical visualizations, the estimation or classification of headlamps regarding their performance at night time driving is very difficult. In this paper a method is presented which uses the zonal flux distribution as a basic principle. With this method, the area into which the light is emitted can be divided into any number of zones limited by geometrical figures (straight lines, rectangles, polygons). The amount of light emitted into each zone is integrated to obtain the luminous flux emitted into this zone. Reference values and weight factors can be applied to each zone to state the importance of availability or absence of light. A mathematical procedure can be applied to derive a list of performance parameters or even one single value, which can be used for comparisons of different headlamps or as quality requirements for manufacturing. The presented method seems to be very sensitive for different mounting conditions and different lighting distributions and it is obviously capable of describing deviations in road lighting by different lighting installations. However, it is not an absolute method for the performance of lighting systems, as the sizes and locations of zones as well as the weighting factors have not been validated with visual comparisons or other means. Further improvements of this method via modification of individual quality parameters are possible.
Estimation of performance parameters for automotive headlamps
Abschätzung der Leistungsparameter von PKW-Scheinwerfern
2003
11 Seiten, 16 Bilder
Conference paper
English
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