For several investigations a concept of a LED headlamp, dedicated to efficiency, was build up at Volkswagen. Whereas the efficiency of the LED source at a certain T,U,I=const is given by the supplier and the SOP of the product, the optical system can be chosen and optimized especially regarding efficiency. Hence, the concept is based on a free form reflection system. Its typical disadvantages in combination with LED sources, the homogeneity and the precision of the cut off line, were prioritized target of the optimization. Because of choosing the light performance of a good halogen system as benchmark, the number of required parts and design space as well as the cooling system and finally the energy consumption can be reduced significantly. The prototype obtains an optical efficiency of 65% including the losses of a complete headlamp. In order to improve the ratio of near field brightness, width, homogeneity and the range of the system two half-sphere reflectors where chosen. This allows a height of the system of 50 mm only. The emitted luminous flux is limited to a minimum of 1000 lumens, set by legal requirement. Hence, the system can be compared to the previously introduced systems. A straight optimization regarding optical efficiency is adverse to an optimal light distribution. In order to improve its quality, the VW benchmark method was used.
New methods of development process of automotive lighting systems
2009
13 Seiten, 15 Bilder, 1 Tabelle, 26 Quellen
Aufsatz (Konferenz)
Englisch
Automotive lighting -- Design and development process
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