Current developments and challenges in LED based vehicle lighting applications

February 21, 2017 // By Andreas Schimmelpfennig, Everlight Electronics Europe
Dashboard and ambient lighting
In addition to the US, Europe remains the most important automotive market in the world. Besides the well-known industry leaders, also new players would like to participate in this market, but often don’t show the necessary corresponding commitment. In the automotive sector, however, investment goes before market penetration. The following article addresses current challenges in the areas of indoor and outdoor lighting as well as qualification and test from the point of view of a manufacturer of optoelectronic components, especially light-emitting diodes.

Interior lighting – dashboard and ambient lighting

In the vehicle interior, a consolidation of the use of LED packages in favor of individual multifunctional diodes can be observed. The decreasing demand results from the increased use of TFT technology in the cluster / cockpit area, but also by RGB LEDs in the ambient lighting, which can be used to display all colors according to the customer's requirements instead of a single LED. The main focus here is on the footwell, but also the side parts of vehicles are equipped accordingly.

For most vehicles fitted with ambient lighting, about 10 RGB LEDs per vehicle are used. Ambient lighting applications were first used in the upper-class vehicles. But now it has also become increasingly popular in medium-class vehicles.

However, in terms of the LED characteristics of ambient lighting with RGB LEDs are concerned, opinions [tend to] differ sharply. In general, the preferred/most wanted wavelength range of red is 620-633nm, green is 520-535nm, blue is 447-471nm. As far as the basic colors are concerned, the desired range is often limited to a maximum of +/- 4 nanometers. But for blue, there are differences: the shorter the blue wavelength, the lower the brightness. Some car manufacturers therefore value a blue over 456nm, some others request a significantly higher figure. For this reason, Everlight has launched four customer-specific RGB versions for different vehicle manufacturers which are available now.

Examples of automotive interior lighting

Especially in the interior, also the requirements regarding white with its respective color grades rise sharply. Many suppliers are confronted with the problem that their plastic light conductors cause a shift in the white point, whereas the overall appearance in the vehicle interior is supposed to further ensure the highest possible uniformity.

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