This is how LED headlights for new cars are developed

This article was published by Telex and Car magazine It can be read in the context of its collaboration.

You might think that developing car headlights can only be done at night, so lighting engineers rest during the day. However, in reality, this work has been carried out in light channels and simulators for a long time.

The Volkswagen Light Channel is at the center of brand development. According to the head of the department, Mathias Thamm, they also deal with light sources in Germany, Mexico, Brazil and China, taking into account local needs and opportunities in each place, including design and cooperation with suppliers. In addition to the above, they also deal with surface optimization and testing when developing headlight functions.

Developing a vehicle is a complex task, so headlight experts must consider how to introduce new technology into a vehicle, and how to make it suitable for mass production.

In recent decades, technical solutions have changed at a rapid pace between halogen, which was dominant for decades, and xenon, which was temporarily used, then LED, and later Matrix LED, and then HD technology, which also necessitated new types of solutions in this area.

From idea to technical description

Developers have to comply not only with European, Chinese or even American regulations when designing their products for these markets, but also with the Volkswagen Group's own regulations. The fact that it is 170 pages long says a lot about the latter. During this process, cooperation with suppliers is also an important and sensitive issue, because care must be taken to maintain brand awareness of, among other things, the non-public parts of the control software.

Today's car headlights offer a lot of functions, from city, corner or intersection lighting to automatic dimming and brightness control to glare-free main beam. They must be coordinated not only with each other, but also with the operation of other systems and sensors in the vehicle.

Following the Volkswagen light channel measuring 100 meters long, 15 meters wide and 5 meters high, we went on a comparative test drive. We started the test with a Polo equipped with halogen headlights, although the brand no longer has one in its range, as LED light sources have also been installed in the small car.

In addition to the uniform light distribution of the conventional solution, the typical yellow color of the light beam, its lower brightness compared to the comparable LED system, and the fact that it emits a much shorter light beam, were eye-catching.

It is worth judging these parameters carefully, because although the measured luminous flux often does not differ, due to the blue color, the LED is perceived as noticeably stronger and brighter. The advantage of modern solutions is even more pronounced in the case of the matrix LED headlights also installed in the Polo, which consist of several light-emitting units that can be controlled independently.

This is the simplest matrix system in the entire Volkswagen range, as there are only eight LEDs per side in the headlights, but it nonetheless illuminates efficiently and pleasantly. The more expensive Tiguan's solution is better and more refined, but the real sensation will be the new HD LED that will debut in the crumpled Touareg, providing maximum illumination with amazingly even light distribution. VW introduced its first LED matrix system years ago, and now up to 19,200 small, individually controllable LEDs light up on both sides in the latest headlights.

Mercedes chose a different path. In the brand's digital headlight, high-performance LED light is directed by 1.3 million moving micro-mirrors with the desired brightness to the desired area. A complex solution has already been added to the A-Class, which has undergone a model update. A new multi-beam LED system evaluates environmental factors every ten thousandths of a second and controls light-emitting diodes at 255 intensity levels.

Today's Mercedes headlight development also begins with design, followed by digital testing in a high-resolution simulator, and then testing on real cars with a specially modified chassis. After all this, serial production is approved, and so the new light source is finally included in the cars available for purchase.

The Mercedes light simulator is inspired by airplanes and other simulators. Development of the system began in 2014-2015, and the goal was to be able to evaluate the operation of each light source under development and the software used to control it, regardless of the time of day or weather, even before the prototype. to make.

Thanks to this solution, they were able to reduce emissions, the process became faster, and the results can be accessed from anywhere. Functional and simulation tests required for certification can also be performed in the virtual environment.

Mercedes' light simulator is built using an E-Class cut in half. From the driver's seat of the car you can see a semicircular screen illuminated by special projectors. Zeiss Velvet projectors typically conjure a starry sky above the heads of audiences in planetariums, and are suitable for projecting delicate light graphics against a deep black background with maximum contrast and accurate color reproduction.

Educational: drawing with light

Built-in simulation software with virtual lighting controllers creates a realistic impression. Even under variable conditions, it demonstrates the capabilities and limitations of individual lighting systems, and can also display light streams in false colors to enhance subjective impressions. Developers can use it to draw graphical representations that show exactly how the light flux is organized, where the light is focused, where and what the electronics cover – or exactly what the measured values ​​are based on which the system calculates it.

Thus, it becomes clear how quickly and precisely everything from sensors to computers and multiple LEDs or headlights with small mirrors must work so that the required amount of light always reaches the desired place. If we could, we wouldn't even get out of the simulator. This higher level of information is very exciting, showing how intensely the background lighting systems work.

The effort pays off in practice, as evidenced by the A-Class and EQS HD multi-beam headlights when driving at night. For an additional fee, Mercedes offers a high-quality headlight for the base model, which provides uniform illumination and a large range thanks to additional bright LEDs. High-precision light provides more consistent illumination, but also supports the driver with special displays if necessary. For example, it warns of danger or draws guide lines on the road. The performance of the simpler Multibeam system is also excellent, proving the importance of development work carried out in the laboratory and in real conditions.