New Automotive Lighting Revolutionizes Road Safety

A German research alliance with members from industry and research has developed the basis for smart, high resolution LED headlights, which takes adaptive forward lighting to a new dimension.
 
The demonstration model was developed by overall project manager Osram in collaboration with the project partners Daimler, Fraunhofer, Hella and Infineon. Both headlights contain three LED light sources, each with 1,024 individually controllable light points (pixels). This means that the headlight can be adapted very precisely to suit the respective traffic situation to ensure optimum light conditions at all times without dazzling other drivers.
 
The light can be adapted to take account of every conceivable bend in the road so that there are no dark peripheral areas. In addition, with the aid of sensors in the vehicle, the surroundings can be analyzed in order to illuminate oncoming traffic. This allows the driver to see these vehicles more clearly.
 
The project, which was funded by the German Federal Ministry of Education and Research (BMBF), has now been successfully completed after three and a half years with the production and field test of headlight demonstrators. For the implementation, Osram Opto Semiconductors, Infineon, and the Fraunhofer Institute for Reliability and Microintegration (IZM) developed an LED chip with 1,024 individually controllable pixels.
 
Electronic activation of the LED is integrated in the chip, resulting in a much higher resolution, while still meeting limited space requirements. For the innovative, high resolution, smart automotive lighting, in a second step, the Osram Specialty Lighting unit developed an LED module. It features an electrical and thermal interface that enables direct connection to the vehicle’s electronics.
 
The feasibility of the system has now been demonstrated successfully in the project; when a smart, high resolution headlight is used, driving and weather conditions are continuously analyzed: What is the course of the road, how fast is the car driving, is there oncoming traffic, and what is the distance between the car and other vehicles?
 
Based on these conditions, the variable, adaptive light distribution ensures tailor-made lighting in every situation. For example, at high speeds, the range of the light beam is increased automatically. In city traffic, on the other hand, wider light distribution improves safety as, in addition to the road, also the sidewalk and peripheral areas are illuminated better. These functions are implemented fully electronically with no mechanical actuators. With glare-free full beam the driver always has the best possible light at night – with no adverse effects for other drivers.
 
“We now want to develop this new type of high-resolution LED light sources so that it’s ready for serial production and we see enormous potential for its use in headlights,” said Stefan Kampmann, CTO at OSRAM Licht AG.
 
Infineon Technologies AG developed the intelligent driver circuitry in the innovative LED chip. This allows each of the 1,024 pixels to be controlled individually.
 
HELLA KGaA Hueck & Co specified the main technical requirements for the light source based on the functional requirements from Daimler. The light and electronics expert developed the entire optical system for the light modules and its cooling concept as well as the prototype headlights.
 
In the research project, Daimler AG specified the functional requirements and the future vehicle properties for the complete headlight system. As regards future electric vehicles, energy efficiency is an important requirement for the newly developed LEDs. A vehicle from Daimler with the smart LED headlights was used for the field trials under real traffic conditions. The current Mercedes-Benz E-Class contains MULTIBEAM LED headlights from Hella which each have 84 individually controllable Osram high performance LEDs.
 
Fraunhofer contributed to the project its competence in connection technology (LED and ICs) and materials as well as in the detection and isolation of defects. The very high resolution was achieved through even finer structuring with miniaturized connection technology. For this purpose, at the Fraunhofer Institute for Reliability and Microintegration (IZM) in Berlin, Germany, LED arrays from Osram with 1,024 pixels were assembled on an active driver circuit from Infineon that controls each pixel individually.
 
Two different assembly techniques were investigated: thermocompression bonding with porous gold nano-sponge and reflow soldering with highly reliable gold-tin. Both assembly techniques proved to be successful with a high yield and a robust interface for the subsequent LED processes.
 
One of the technological challenges of the high-resolution LED headlight is the comparatively large chip with 1,024 individually controllable pixels. This is because as the LED chip size increases, it raises the risk of failure or decreased luminosity of the individual pixels in the pixel matrix during the production process. To overcome this problem, the Fraunhofer Institute for Applied Solid State Physics IAF in Freiburg, Germany developed a new technology to repair defects. It is based on ultraviolet laser micromachining and enables defects in LED chips to be repaired during the production process.
 
The economic benefits of laser micromachining from the Fraunhofer IAF are not only in reducing defects during production and thus lowering production discard and costs for large LED chips: The process can also increase the average life of the LEDs, which is an important competitive advantage and raises customer satisfaction.
 
The μAFS project was supported by the German Federal Ministry of Education and Research under funding ID 13N12510. It ran from February 2013 to September 2016.