In the rapid introduction of LED-technology in automotive headlamps, the realization of a day time running light which is fed by only one LED (a socalled ONE-LED-DRL) has been a dream for a long time. In this context, the recent achievement of efficiencies of about 100 lm/W for white 1-W-LEDs is a critical milestone. Therewith, the luminous flux out of one single LED can be sufficient to - adequate driving current and a highly efficient optical system supposed - realize a ONE-LED-DRL. These ONE-LED-DRLs are a revolutionary future trend as far as power consumption, simplicity of mechanical and electrical design, weight and costs are concerned. However, the use of only one light source and the necessity of a highly efficient optical system suppose stringent restrictions to the design. The following question seems justified: Which design freedom remains with a ONE-LED-DRL? Nevertheless, a restricted toolbox for creating both efficient and beautiful ONE-LED-DRLs remains: First, different light sources with different ray characteristics allow the variation of the night appearance. Second, due to further improvements in the luminous flux of the LEDs, optical concepts and geometries which allow spending some luminous flux to the design and which therewith are not purely efficiency-driven may be realized. These different aspects will be discussed and illustrated by optical simulations for different light sources and different designs. The evolution for LED-DRLs goes on and significant design potential exist for ONE-LED-DRL due to further developments in the LEDs. The design potential may consist at least in the following parameters: optical systems, geometries and ray characteristics. As design freedom is always inversely proportional to optical efficiency and therewith directly related to power consumption, of course, highly designed ONE-LED-DRLs will not be the most efficient ONE-LED- DRLs. However, the power consumption will always range in a few Watts and therewith at the lower limit of all existing DRLs. As a consequence, ONELED- DRLs are not determined by "efficiency versus design", but by "efficiency and design".
The ONE-LED-DRL: Efficiency versus Design?
Der Ein-LED-Frontscheinwerfer - Wirkungsgrad im Verhältnis zu Design
2011
9 Seiten, 4 Bilder, 1 Tabelle, 1 Quelle
Conference paper
English
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