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Technical Paper

Influence Parameters on Headlamp Performance in Rating Systems and Reality

Headlamp performance has changed in the last 20 years significantly. Sealed beam lamps were replaced by VHAD, VOR and VOL types, but still the optical input in terms of tungsten filament based luminous flux remained more stable. With Xenon discharge lamps and now LED the performance of a headlamp may vary strongly and thus the optical performance. Various rating systems have been developed to assess the quality of lamps and light distribution, some based on laboratory based data, some based on static or dynamic street test drives with online measurements and assessments. Basic interest is to understand the performance of the light for a real driver. This article will discuss the influence parameters on achieving a repeatable and precise rating as well as the outer influence that creates glare and varying seeing distance. Mostly mechanical headlamp and car conditioning will influence the result as well as human factors like aiming precision and aiming tolerances.
Technical Paper

Green Lighting: Analysing the Potential for Reduction of CO2-Emissions in Full LED Headlamps

The first All LED headlamps have arrived in the market, providing all lighting functions with semiconductor based light emitting devices, LED. That was a huge step: the first fully electronic headlamp of the world. Aside from photometry and lifetime advantages, LED offers opportunities in saving CO2-Emissions and thus reducing Energy consumption. 2008 was for the first time a headlamp available where all lighting functions including low and high beam were completely realized with Light Emitting Diodes (LED).
Technical Paper

The Continuous Emerging of LED in Headlamps: Challenges and Technical Solution for LED Fog Lamps

After the first series applications with LED in headlamp signal functions are on the road or close to production release, the next continuous steps are considered in the paper. Side markers and Position lamps, Daytime Running lamps and Turn Indicators are considered to be in a technology ready status. Despite the fact that fog lamps have low luminous flux and photometrical requirements, the challenges due to glare avoidance and aimability via cut off line have reached a new level. Technical concepts and performance will be discussed with measurement data evaluation. Due to the fact that different LED suppliers are on the market with different optical and mechanical solutions, a matrix evaluation will be driven for photometrical and efficiency potential. Another significant impact will be the styling influence of the exit apertures. Studies for LED fog lamps will be presented. Several LED sources require a dedicated electronic driving concept.
Technical Paper

Safety and Comfort: Advanced Methods to Analyze Headlamp Light Performance

This paper will present a new method to describe headlamp light distributions by taking into account visible performance, measurable lighting parameters and physiological comfort aspects. Up to now, headlamp light distributions have been evaluated by looking to photometric measurements, which are displayed as isolux or isocandela values. Based on investigations intended to examine the driver's basic requirements for a good light distribution, the resulting measurement tools are split into two sections to describe the performance: Safety and Comfort. For both sections, the tools are described and demonstrated with two light distributions that show different behaviour. The Safety evaluation tools are defined and presented. For the Comfort of driving, the light distribution generated on the street concerning luminance, contrast sensitivity and homogeneity are further parameters. A new possibility of defining a single quality parameter for the homogeneity is given.
Technical Paper

System Strategies and Technology for Improved Safety and Comfort with Adaptive Headlamps

The introduction of innovative new technologies is related to aspects of safety and to human factors as comfort level and visual appearance. The intelligent headlamp system that is currently being developed allows the combination of the different aspects of driving comfort and safety. The top performing headlamp generations of the future will be the successors of the today’s standard low beam. By using the sensor information available in the car, the light distribution will be adapted to different driving situations and generate an optimized light distribution. Relaxed and safe driving is the goal. Investigations concerning adaptive headlamps are presented. Highway, country road, curves and turning situations are examined by investigating detection distances of standard objects and by rating safety and comfort. Photometric measurements rating glare effects during curve road driving for different headlamp control algorithms are carried out.
Technical Paper

Measurements and Ratings of HID Headlamp Impact on Traffic Safety Aspects

High intensity discharge lights (HID) are the innovation step that is now beginning to penetrate in all car classes. Investigating drivers, all results show that the benefits are visible to them and positively accepted. The quantification of the improvements has yet been insufficiently examined. In this article some of the aspects will be highlighted.
Technical Paper

Software Controlled Homogeneity Analysis of Headlamp Light Distribution

This paper will describe the procedures that will enhance the possibilities of qualitative evaluation of headlamp light distributions. A basis will be the description of a light distribution coming only from reflector geometries, i.e. headlamps with clear outer lens design. Further steps of evaluation, as visualization and homogeneity analysis become more and more important for a headlamp evaluation. The recently developed tools can support both the headlamp manufacturer and the car manufacturer in finding a common understanding in headlamp performance of a projected car at a very early stage of development.
Technical Paper

HID Headlamp Development: Performance Benchmark, Market Penetration and Future Styling Development in World's Markets

After about one decade HID headlamps are available on all major market areas. Since the design and manufacturing possibilities have changed in that period, the current light performance will be reviewed in the paper. The market penetration in the three major markets shows obvious differences. The penetration related to car platforms and classes will be discussed. It will be shown that HID headlamps have different penetration level in US, Japan and Europe. Additionally, the future styling development will be evaluated by the technical possiblities given today using reflector/projector type and additional illuminated areas. A future styling trend will be estimated for the three different markets. The future application of HID headlamps in adaptive lighting systems will be analyzed.
Technical Paper

Innovations in Lighting with Adaptive Headlamp Technology

The development of headlamps was found to experience a dynamic process. For more than 50 years the tungsten double filament bulbs (Bilux) had been dominating the lighting technology, followed in the seventies by the H4 bulb. Since the middle of the eighties the modern filament bulbs as H7 (now H9, H11) have been available. The Xenon gas discharge (or HID-) technology reached the automotive market in the nineties. Now the development is heading towards the new technology step. Adaptive „intelligent“ headlamps will bring the headlamp from its isolation in the front module back into the world of electronics and car networking systems.
Technical Paper

Necessity of New Approaches for LED Headlamp Design

The characteristics of the semiconductor based Light Emitting Diodes (LEDs) is completely different to the characteristics of traditional light source used in automotive exterior front lighting systems. The characteristics include not only optical items, but also electrical, mechanical and temperature issues. These characteristics make new approaches in the field of automotive headlamp development necessary. Due to the designer's wishes, the LEDs must be mounted on a 3-dimensional surface with small tolerances to the associated optics. High power LEDs create a lot of heat, so that they have to be assembled with a cooling device. The generated heat should be used for defogging and deicing of the outer lens of the headlamp. Electrical drivers are needed to keep the current through the LED constant. All new technical challenges will lead to more stylistic freedom
Technical Paper

Luminance Measurement, Contrast Sensitivity, Homogeneity: New Approaches of Defining the Quality of Headlamps

The conventional measurements to describe the photometric quality of headlamps usually only comprise the luminous flux and the illuminance (resp. the luminous intensity) in several measuring points given by Type Approval Legislation. Practically, these photometric measurements do not describe the visual impression of a headlamp light distribution sufficiently, neither in lab nor in real street geometry. With the clear outer lens headlamps introduced recently, filament images are projected directly onto the screens or streets, thus giving new impulses to research. Starting from the established photometric practice, other types of measurements and physiological fundamentals will be discussed. The basic tools to make physical measurement and physiological impression comparable, e.g. in terms of homogeneity, are shown.
Technical Paper

Design Claims and Technical Solution Steps Generating the World First Full LED Headlamp

1 In 2008 the first full LED (LED = Light Emitting Diode) headlamp will arrive to the worlds markets, providing all lighting functions with semiconductor based light emitting devices, LED. The first Full LED headlamp differs in style and technology from other headlamps. Target was to find a face that fulfils the demands of the stylists and also gives the possibility to be assembled, to fulfill customer specs and legal requirements. Fulfilling this, the development showed various intermediate steps. As LED is still a evolving technology, mature and fixed technical solutions were and are not always existing. So technical solutions had to be developed under the constraints of new technology and regarding the existing mechanical and electrical environment in the car.