Sunday, October 5, 2008
LED Head-lamp - Study by HELLA
Development : Luminous flux equal to xenon
Hella is developing complete headlamps using LED technology as a study provides information about possible series application from 2008.
The light and electronics specialist Hella, in cooperation with Volkswagen, has developed an LED headlamp which achieves low beam, high beam, direction indicator and daytime running light functions using cutting-edge LED technology only. The LED headlamp is a study using the VW Golf 5 as an example. It is to provide information about the performance ability of such systems and also offers the possibility of experiencing technical challenges in operation in the vehicle. A series solution is expected for the year 2008.
For the lighting functions, Hella uses both standard LEDs and LED assemblies especially designed for automotive applications. The light is directed onto the road with the aid of different optical systems. The most striking part of the headlamp is formed by seven pentagonal plastic lenses arranged in a honeycomb pattern. There is a shovel-shaped free-form reflector positioned next to these which produces the low beam together with four segments of the honeycomb. For the high beam, the other three segments of the honeycomb are also used. During the day, all seven segments of the honeycomb form the daytime running light. There are six standard LEDs arranged in a row beneath the shovel-shaped free-form reflector for the direction indicator function.
Light emitting diodes as a light source open up completely new possibilities for headlamp shapes and arrangements. This is made possible by the modular design as well as the large selection of different optical elements.
From the styling point of view, headlamps for future vehicle generations can be given a completely new look. The development of white LEDs in particular is creating application possibilities that would have been inconceivable only a few years ago. Alongside design aspects, the main reason for the development of this new headlamp technology is the reduced need for maintenance . The aim is to develop a headlamp which functions perfectly for the life of the vehicle.
Already, the LED headlamp prototype achieves a level of around 1,000 lumens luminous flux in the low beam, and has thus reached the level of a xenon headlamp. The luminous flux necessary for good high beam light cannot yet be attained on account of the lower luminance of LEDs. Hella's lighting specialists are convinced, however, that this will soon be achieved in the course of the further development of LEDs. The technical challenges that need to be solved by then involve thermal management in particular, as well as the development of new production processes and optical elements to accompany the LED technology.
n the USA headlamps with LEDs for main lighting functions are already approved according to the SAE standards valid there. In Europe or rather within the area of validity of ECE regulations, approval can be expected by 2008. Signalling functions in headlamps (direction indicator, position light and daytime running light) using LEDs are already approved in both the ECE and SAE regulated regions.
As early as in 2003, Hella achieved the world's first series application of white LEDs as a combined position and daytime running light in the headlamp of the Audi A8 W12. In the rear signal lamp sector, the company has successfully been using LEDs as light sources for more than ten years now, in high-mounted stop lamps, for example, or for tail light, stop light and direction indicator functions in combination rear lamps, such as in the case of the Volkswagen Golf Plus.
Hella has also been using LEDs for single-function lamps and combination rear lamps in the aftermarket and commercial vehicle sectors for quite some time. Thanks to their long service life, low power consumption and compact design, LEDs have already become standard for position and side marker functions. These properties also make LEDs particularly suitable for the current trend towards daytime running light applications.