LED lighting The future of LEDs in automotive lighting

Autor / Redakteur: Peter Knittl * / Dipl.-Ing. (FH) Hendrik Härter

Nothing is as ubiquitous and at the same time as challenging and varied as the lighting for motor vehicles. This has led to a steady stream of developments and new products – from matrix lamps to laser light.

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Red Backlight: The striking design of this vehicle taillight is also known as a quasi-3D effect. It can be achieved with Power Sideleds from Osram Opto Semiconductors, for instance.
Red Backlight: The striking design of this vehicle taillight is also known as a quasi-3D effect. It can be achieved with Power Sideleds from Osram Opto Semiconductors, for instance.

Major differences in temperature, moisture and vibrations – automotive lighting is a real challenge. The situation is compounded by strict requirements imposed by vehicle and lamp manufacturers (both OEMs and setmakers). Strict statutory rules must also be observed, in addition to these operational requirements. These rules are laid down by the United Nations Economic Commission for Europe (UNECE).

It specifies the color of the light emitted from the various lighting units (headlamps, turn indicators and taillights) to ensure that all road users know exactly what to expect when they encounter light of different colors on the road. Maximum and minimum values are also specified for the intensity of high beam and daylight running lights as reliable illumination of all vehicles on the road is important when it comes to ensuring the safety of all road users.


LEDs are an outstanding light source

With the right light, the road itself and the surrounding area are ideally illuminated, and signs, pedestrians and obstacles can be identified more readily. At the same time, a limit on the maximum intensity will avoid glare which endangers other road users, potentially causing serious accidents. Due to their numerous advantages, LEDs (light-emitting diodes) are clearly on the ascendant. They instantly deliver the full luminous flux as soon as they are switched on, and even innumerable switching cycles cannot impair their performance.

Apart from their extreme energy efficiency, they also boast an exceedingly long life span and compact size. This latter property is currently in great demand among car makers, as it opens up a wide range of design options. More and more headlamps hence are using LEDs for accentuation or as the sole light source.

Leading car makers have for many years focused on cool designs with a high recognition factor. The small size of light-emitting diodes opens up virtually endless possibilities, particularly in headlamp design – and design engineers are keen to exploit this. In the early days, daytime running lights made up of individual LEDs were designed to resemble eyes complete with arched eyebrows.

Today, we are more likely to see lighting solutions with a three-dimensional effect, particularly when used in taillights. This striking option has become a favorite of designers, especially in the automotive premium segment. Light effects like these can be achieved with light-emitting diodes of a very high luminous intensity which radiate light laterally, such as the Power Sideled from Osram Opto Semiconductors.

Collaboration on light innovations

Considerable requirements are therefore imposed on light manufacturers in the automotive sector, for the light sources not only have to meet demanding operating conditions, but must also comply with statutory regulations and the requirements specified by OEMs. High product quality and a long operating life are therefore essential. And that is also why cutting-edge light sources are frequently used in automotive applications before gradually being introduced in other areas. An ongoing dialogue and close collaboration are hence invaluable, in order to satisfy both the car manufacturers and the setmakers. This is particularly true when advancing innovations.

Research projects are one example of how academia and industry work hand in hand, in a joint effort to develop innovative products. Osram Opto Semiconductors is currently involved in numerous projects in various sectors, either in a leading role or as a partner. The purpose of these projects is to collaborate on developing and advancing light applications which could trigger an upswing in individual areas or sectors, such as the automotive sector. The light source itself is only a small part of the larger whole.

What is important is that all partners work together closely, much like cogs in a well oiled mechanism. Each partner contributes its own specialist know-how to these research projects, be it in the field of beam patterns, design, temperature management or electrical control systems. Innovative new market applications can only be developed quickly by working together in funded projects. The µAFS project funded by the Federal Ministry of Education and Research as part of its focus on “Integrated Microphotonics”, aims, for instance, to develop the technical principle for a new class of energy-efficient LED headlamps which may then provide the basis for adaptive frongt lighting systems.

These systems produce the best illumination at all times because they adapt the distribution of the light according to the driving and traffic situation without dazzling other road users. In October 2014, almost one and a half years into the project, the partners presented the first milestone: an LED chip with 256 pixels. The prototype was developed jointly of experts at the project coordinator Osram Opto Semiconductors, Osram Specialty Lighting, Infineon Technologies and the Fraunhofer Institute for Reliability and Microintegration IZM. In previous adaptive frongt lighting systems (AFS) one pixel corresponded to one LED component or one chip, whereas in this prototype one chip contains 256 pixels which can be individually controlled.

Following this initial milestone, other partners (Hella and Daimler) will take over in the quest to achieve the ultimate objective of the project, namely the development of a prototype headlight. A single partner acting alone cannot tackle all these different tasks. They can only be accomplished through coordinated efforts and close cooperation between all the parties involved, and any progress made must be communicated and coordinated without delay.

Adaptive beam patterns such as those which the µAFS project aims to develop can only be achieved with LED technology and corresponding control systems. Dynamic adaptive forward lighting systems (AFS) with a high resolution enhance the safety of both drivers and passengers. Among other things, they include glare-free high-beam and low-beam lights whose beam pattern adapts to the speed of the vehicle: at higher speeds, the reach of the beams increases automatically. In urban traffic, on the other hand, safety is improved by an adaptive, wider beam pattern illuminating the sidewalk and peripheral areas, as well as the road itself. These functions are fully electronic, requiring no mechanical actuating motors – and the development process is nowhere near its conclusion.