What is in this article?:
Smart lighting can be used to better illuminate roads, signal pedestrians in the path ahead and wake up drowsy drivers.
LED and sensor technology afford greatest variability in light-distribution patterns for city, country and highway driving with glare-free high beam light.
Sensors Make Light More Variable
With LED technology, control of the light-distribution pattern is almost infinitely variable, meaning it can be adapted to the driving situation, particularly on country roads. Adaptation depends not only on speed, but also on distance to the car ahead, the course of the road and any oncoming traffic.
If the system detects a highway or a highway-like road, it can select the right beam pattern even at low speed. For distance measurements, rapid-pulse laser diodes for LIDAR systems are available. To obtain more detailed information on the surroundings, a camera with a strong infrared light source (headlight) can be used to detect and classify objects in the vicinity of the vehicle without obstructing the vision of oncoming traffic.
At present, the absolute latest in adaptive front lighting development is glare-free high-beam light. With this technology, oncoming cars, vehicles ahead and – with the latest systems – even pedestrians are selectively shaded, or protected from glare. At the same time, drivers can exploit the advantages afforded by the long range of high-beam light: They can see farther, and that is a significant safety gain for all road users.
For example, the high-beam light reaches even beyond the vehicle ahead, enabling the driver to see pedestrians, cyclists and obstacles on the right-hand side of the road sooner. Cornering lights also fall into the category of using alternative light-distribution patterns. Under current regulations, headlamps are permitted to track the turn of the steering wheel up to 15 degrees.
These options already exist with classic light sources, such as xenon lamps. However, new LED light sources for headlamps offer a number of more extensive possibilities.
LED automotive headlamps always contain several LEDs. High-performance systems can have as many as 30 LEDs, each of which can be switched on and off separately. Together with the optical system that comes with every LED, alternative light-distribution patterns can be generated entirely without mechanical elements. One example is the matrix headlamp, such as that installed in the Audi A8.
With these headlamps, the high-beam light initially can be masked in two zones, meaning, for instance, separately for a vehicle in front and oncoming traffic or a pedestrian. This greatly enhances safety because the rest of the road, and thus also obstacles on it, are still fully illuminated.
In some situations, the driver ahead even has an advantage in that the glare-free high-beam light shines along the side of his vehicle, illuminating the road beyond. Furthermore, with matrix technology, the area directly in front of a vehicle can be illuminated brightly by additional LED light sources, with no deterioration in the light falling at a distance. Many drivers prefer good lighting directly in front of the car – although it is technically not necessary – because it is considered a pleasant effect. It promotes relaxed driving and therefore also enhances safety.
LEDs immediately deliver full luminous flux when switched on and they do not require numerous start-up cycles. No other automotive light source offers these advantages. Matrix light and its highly adaptive light-distribution patterns are possible only with LED technology. And developments still have a long way to go.
It already is possible today, for example, to briefly illuminate a pedestrian so there is no doubt the driver sees him. More extensive marking functions are conceivable in the future, such as signs along a planned route or the correct exit lane. The new technology also offers special advantages for responding to a frequent demand from many drivers for “bad-weather lighting.”
Until now, only the fog lights were available for this purpose, but their decades-old beam pattern is incapable of adequately handling the diverse visibility problems caused by the weather. Now, lighting engineers can develop optimum settings for rain, snow or fog.
Walter Rothmund is senior marketing manager-IR Components for Osram Opto Semiconductors.