For years, automotive lights were only used to illuminate the road or provide visibility to the following traffic and indicate any actions such as backing up or turning.
In the last 10-15 years automotive lights became more and more a styling effect of the car where designer put a lot of effort in to make the car attractive and give it its individual and distinctive look. At the moment there are numerous light sources being applied in the automotive lighting industry, ranging from traditional incandescent bulbs and HIDs to LEDs, laser diodes, and soon OLEDs. Although the design and the influence of the light source on the design has changed drastically over the years, one thing is a constant: the thermal management of the headlamp.
With halogen, the high temperature of the bulb caused issues by radiation and high temperatures in the convection plume were critical factors for the surrounding plastic components. Now, LEDs and laser diodes are far less hot but the critical temperature is a problem for the light source itself rather than other components.
With various diodes from different vendors the thermal properties as well as optical properties are also varying a lot. New problems which were not considered before are coming into focus. With the new light sources, the automotive industry wants to leverage the long lifetime, to give advantages to the designers and also to increase efficiency. As these needs have to be validated for the application in the high demands of the automotive industries, measurement techniques such as the thermal and radiometric characterisation are key.
It doesn’t take an expert in automotive lighting to see how much the design of the lights have changed and how much more complicated the design has become. The exterior look does not show what is actually behind the bezels with all the new technologies for adaptive beams and LED matrix beam, etc. Often each LED gets its own lens held by a fixture and light guides are used more and more in the design, with small saw-tooth structures to direct the light to the road and the external viewer. All these new structural changes and components cause the overall complexity of the headlights to skyrocket. Read this week’s in-depth report for an update on the issues and state-of-the-art solutions.
DVN Editor in Chief