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Liquid Crystal Display

Integrated into headlights

Published 2017-08-01

Hella has developed LCD headlamps. In one approach, the pixel light distribution is calculated in an IC in the headlamp, which is connected optionally to CAN.

(Photo: Hella)

In the context of the research project funded by the German Federal Ministry of Education and Research (BMBF) regarding the fully adaptive light distribution for intelligent, efficient and safe vehicle lighting (VoLiFa2020), Hella has developed and constructed a headlamp on the basis of a Liquid Crystal Display (LCD). Project partners include Merck, IGM institute of the University Stuttgart, Porsche, Elmos Semiconductor, Schweizer Electronic, and the University of Paderborn. This technology is for example already known in the home entertainment field. "For the first time, we have integrated Liquid Crystal HD technology in a vehicle. Thanks to its great resolution and sharpness of detail, it opens up very new paths in automotive lighting technology", said Dr. Michael Kleinkes from Hella.

Overall, the LCD headlamp projects 30 000 pixels onto the road. This allows adjusting the light pattern in a smart and continuous manner to various driving situations in real time. "The use of an LC display is a further step towards digitalizing lighting", said Christian Schmidt from Hella. This means: The adaptation of the light pattern is increasingly be determined by software. The driver obtains the best possible view of the road. Individual segments with e.g. other traffic participants or strongly reflecting street signs can be omitted or dimmed in a targeted manner. Highly complex functions are also conceivable. Navigation arrows or lines showing the ideal lane can be projected onto the road. "LCD technology enables functions that will also be relevant to autonomous driving", said Christian Schmidt. "We will therefore make the technology fit for serial production."

LCD headlamps adjust light distribution to different traffic situations in real time (Photo: Hella)

The LCD is the headlamp's key component. It is situated between the LED light source and the projection lens. The display generates a matrix with 100 x 300 pixels that can be individually controlled and dimmed. A camera installed in the vehicle as well as a sensor optically reading distances and speeds (lidar sensor), forwards the ambient information to the headlamp control unit via a processor. This then directs the individual display pixels up to 60 times per second. 25 high-power LED's arranged in three rows will serve as light source. Each LED's light intensity is adjusted to the respective lighting situation.

Hella developed the concept for the LCD headlamp's optical system during the research project. The system requirements of automobile manufacturer Porsche and the Research Institute for Lighting Technology and Mechatronics of the University of Paderborn (L-LAB) served as foundation. Ensuring high system efficiency and a thermal concept guaranteeing the automotive suitability of the module were among the various Hella tasks. A special liquid crystal was required here, which Merck developed for this purpose. Using this chemical component, the IGM developed and built prototype displays. Elmos Semiconductor designed and built innovative electronic semiconductor components, which Schweizer Electronic embedded into the PCB (printed circuit board). This technology allowed the experts realizing a reliable, efficient and space-efficient control of the LED lighting unit. Hella provided the integration of the various components into the overall system and developed an interface between lighting control and headlamp. A prototype resulted, which – integrated into a Porsche Panamera – is currently being tested under realistic driving conditions by test drivers at the University of Paderborn.

Due to increasing traffic volumes and safety requirements, smart lighting systems are of increasing importance. LCD technology enables completely new functionalities and opportunities here. And the use is not limited to passenger cars. Other vehicle categories, such as commercial vehicles or buses also provide meaningful application areas.

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