Vorsprung in lighting technology:
Be they matrix laser headlamps or organic LEDs, the light innovations that Audi is bringing to market over the next few years combine aesthetics with amazing functionality.
Functions of matrix laser technology
Only the moon is reflected in the hood. Otherwise, all is completely dark. However, this night is an illusion. Outside the sun is shining and the “moon” is a ceiling lamp inside the light tunnel in the Audi Light Assistance Center. Stephan Berlitz steps toward the prototype. He knows it best, because he is the person responsible for developing light innovations at Audi. His work has long since ceased to concern itself with individual headlamps – the car in front of him is a complete artwork of light technology.
Berlitz pulls his smartphone from his pocket and uses an app to unlock the doors, at which point he is met by a personal greeting: The front headlamps project “hi there” and the crest of Bayern Munich, his favorite soccer team, onto the ground. The distinctive signature of the daytime running light appears, framing the next step in automotive illumination – matrix laser technology.
At the heart of the new front headlamps is a high-power laser which illuminates a matrix of almost half a million micromirrors. Their edges are only a few hundredths of a millimeter in length and each one can be individually tilted up to 5,000 times per second. “In future, we won’t have any more LEDs in the headlamps, unlike the current matrix-LED in the Audi A8, but several hundred thousand individual pixels,” says Berlitz. “The development leap is like the difference between the TV table tennis we had in the 1970s and the Playstation 4 we have today. These are worlds apart.” So-called DMD technology (Digital Micromirror Device) is already in use today in many video and cinema beamers.
The matrix laser technology obviously also offers far more than just personal greeting gimmicks. While the headlamps provide perfect road illumination in all situations, they also precisely mask out other road users so that no-one is dazzled by the permanent high beam. Plus, objects such as traffic signs or pedestrians at the side of the road can be marked by light and thus individually highlighted. This raises driver awareness and, with it, safety. Alternatively, traffic signs can be specifically blocked to ensure the driver can see them clearly without being dazzled by the reflection from the bright high beam.
A wide variety of shapes and signals can also be projected onto the asphalt. So for example, on particularly narrow roads or lanes, two strips of light shine onto the road where the car is about to drive to show the exact driving line and the width of the vehicle. “We all know that uncomfortable feeling when the lane gets very narrow driving through a construction area,” says Berlitz, outlining the situation. “Am I going to get past that wide truck?” The light tracks give drivers a secure feeling and they are far more relaxed when they drive through the bottleneck.”
And the lighting expert goes one step further. When piloted driving has revolutionized the automotive sector a few years from now, matrix lighting will be able to make even more of its potential, as there will be a need for completely new forms of communication between road users. “The car will be able to communicate with pedestrians in a number of different ways,” explains Berlitz. This also applies to when the driver is momentarily distracted, by reading e-mails for instance – because, in future, the car will drive itself. There could be light signals to indicate the direction of travel, or carpets of light to assist decision-making at crosswalks.
Berlitz walks around a prototype and is followed by homogeneous illumination from OLEDs (Organic Light Emitting Diode) gracing the flanks of the OLED Lighting design study. “The light follows the driver around the car and indicates, for example, where the door handles are,” explains Berlitz, thinking about the future possibilities presented by this technology. “That obviously applies to the inside, too. The interior will merge more and more with the exterior.”
At the rear end, the two rear-light clusters shine with razor-sharp contours. Several small “light tiles” are arranged artistically inside them. Organic LEDs are in use here, too. An individual OLED can be the size of a smartphone display, but the material beneath it is less than one millimeter thick. This presents countless opportunities for design.
Each “light tile” consists of seven different layers stacked one on top of the other. Some are for the purpose of component efficiency, with the most prominent, however, being the emitter layer. In each OLED, two electrodes, at least one of which has to be transparent, encase multiple, thin layers of organic semi-conductor material. A low-voltage direct current – between three and four volts – cause the layers, each less than a thousandth of a millimeter thick, to light up. Like conventional LEDs, OLEDs are based on the phenomenon of electroluminescence.
In contrast to point light sources like LEDs made from semi-conductor crystals, OLEDs are flat light sources. The technology does not require reflectors, light guides or additional optics to achieve its homogeneous appearance. An OLED can be divided into as many light surfaces as required, each of which can be individually controlled. Audi development engineers and designers are thus able to clearly delineate different levels of brightness on a single “tile”.
Three-dimensional LEDs will soon be entering series production. “In flexible OLEDs, the substrate material is simply a film – instead of rigid glass,” says Berlitz. “We can use this to design totally new shapes and achieve completely new, three-dimensional effects. This combination of aesthetics and highly innovative technologies is something we will continue to push in future, because OLEDs offer us even more progressive design options,” says the lighting engineer with visible glee.
Alongside their low energy consumption and long life span, OLEDs have a further benefit in the wide angle of their beam. This makes the vehicle far more recognizable, leading to increased road safety.
It’s suddenly light again in the tunnel and the moon backdrop fades. But the prototype with the impressive innovations is still there. These innovations, which still look so very futuristic, will be driving on public roads just a few years from now. This also applies to matrix laser technology, as soon as the legislative authorities give it the green light.
Around one third of the legal requirements for cars are associated with lighting. “The signals, be it the indicators or the brake lights, have to be very clear and unmistakable,” explains Berlitz. There are also a great many regional differences: “We still can’t deliver our matrix LED headlamps in the USA, for instance, as there’s still no applicable legislation.”
"The combination of aesthetics and highly innovative technologies is something we will
continue to push in future, because OLED offer us even more progressive design options."
The shared origin of light
Matrix laser and OLED may seem like two completely different technologies, yet they share the same origin – the LED. “It has given rise to two different concepts,” says Stephan Berlitz, Head of Development Light Innovations/Functions at Audi. “On the one side, ongoing development is moving toward high performance, which is the laser light source.
The other direction is aimed at laminar illumination, where OLED is the solution. If I need more light, I take laser. If I would rather create design elements, I choose OLED. The shared basis, however, is a normal LED light source.”
The light assistance center
Beneath the earth of the Audi factory site in In golstadt is a tunnel more than 120 meters long, and it offers Audi all possible options when it comes to the development of new light technologies. The Light Assistance Center (LAZ) was connected to Audi’s old light tunnel in 2015. It encompasses a laser lab, a turntable, a weigh scale for cars, a media room and, not least, a floor similar to a road surface. Audi uses further spaces for the development of interior lighting. At the end of the tunnel is the so-called dome, which is 18 meters wide, nine meters high and 25 meters deep.
Audi’s new light tunnel has impressive dimensions: 120 meters long, twelve meters wide and five meters high. It offers development engineers all possible options for working in the dark, even during the day.
Development focus is currently on innovative solutions for high beam as well as camera- based light assistance system, which will likewise find their way into series production in future. The new LAZ makes many nighttime drives superfluous, as Audi can now work in the dark even by day – meaning the development can make it onto the road even faster.
Timo Pape (text), Ulrike Myrzik (photos)