High-resolution vehicle headlamps are the technological way to intelligently illuminate the traffic area to increase safety and comfort. For the technical realization of these headlamps, different technologies come into question, which are the subject of intensive research at universities and among the manufacturers. We present an overview of the possible technologies and analyze their potential for use in high-resolution headlamps. Furthermore, we explain how the design of the optical system for the different technologies can be made. Another part of this paper is the comparison of published prototypes of high-resolution headlamps and the compilation of key properties.

High-resolution vehicle headlamps represent a future-oriented technology that can be used to increase traffic safety and driving comfort. Typically, selective absorbing of light using a spatial modulator like DMD, LCD or LCoS creates the light distribution of such headlamp systems. A similar effect can be generated by using LED arrays. Its additive principle generates light only in specific segments if necessary. In general, these arrays can be distinguished between conventional LEDs arranged in an array and micro pixel LEDs. Conventional LED arrays characterize by the design (THT or SMD) with typically a few millimeters edge length. In contrast, a micro-pixel LED uses COB technology, in which individual LED dies are packed in a single housing directly next to each other at a distance of a few microns. By increasing the array resolution, the challenges in designing an optical system for high-resolution headlamps rise. High efficiencies and contrasts call for small, accurate lens geometries and negligibly scattered light effects. Due to limited installation space and manufacturing tolerances, compromises have to be made. Ideally, the optics have to be accurate enough to image each pixel of the micro LED with high contrasts and high efficiency and still be too blurry to project the gaps between each pixel. This results in small distances between LED and optics and therefore in difficult to manufacture radii of curvature. In this paper we specify the challenges to implement micro pixel LEDs in headlamp systems, as well as present the controllability of scattered light effects of these systems.

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High-resolution vehicle headlamps represent a future-oriented technology that can be used to increase traffic safety and driving comfort. As a further development to the current Matrix Beam headlamps, LED-based pixel light systems enable ideal lighting functions (e.g. projection of navigation information onto the road) to be activated in any given driving scenario. Moreover, compared to other light-modulating elements such as DMDs and LCDs, instantaneous LED on-off toggling provides a decisive advantage in efficiency.To generate highly individualized light distributions for automotive applications, a number of approaches using an LED array may be pursued. One approach is to vary the LED density in the array so as to output the desired light distribution. Another notable approach makes use of an equidistant arrangement of the individual LEDs together with distortion optics to formulate the desired light distribution. The optical system adjusts the light distribution in a manner that improves resolution and increases luminous intensity of the desired area.An efficient setup for pixel generation calls for one lens per LED. Taking into consideration the limited space requirements of the system, this implies that the luminous flux, efficiency and resolution image parameters are primarily controlled by the lens dimensions.In this paper a concept for an equidistant LED array arrangement utilizing distortion optics is presented. The paper is divided into two parts. The first part discusses the influence of lens geometry on the system efficiency whereas the second part investigates the correlation between resolution and luminous flux based on the lens dimensions.

Highly adaptive light sources such as LED arrays have been surpassing conventional light sources (halogen, xenon) for automotive applications. Individual LED arrangements within the array, high durability and low energy consumption of the LEDs are some of the reasons. With the introduction of Audi's Matrix beam system, efforts to increase the quantity of pixels were already underway and the stage was practically set for pixel light systems. Current efforts are focused towards the exploration of an optimal LED array density and the use of spatial light modulators. In both cases, one question remains-What arrangement of LEDs is the most suitable in terms of light output efficiency for a given lens geometry? The radiation characteristics of an LED usually shows a Lambertian pattern. Following from the definition of luminous efficacy, this characteristic property of LEDs has a decisive impact on the lens geometry in a given array. Due to the proportional correlation between the lens diameter and the distance of LEDs emission surface to the lens surface. Assuming a constant viewing angle an increase of the distance leads to an increase of the lens diameter In this paper, two different approaches for an optimized LED array with regards to the LED arrangement will be presented. The introduced designs result from one imaging and one non-imaging optical system, which will be investigated. The paper is concluded with a comparative analysis of the LED array design as a function of the LED pitch and the luminous efficacy.