The automotive lighting technology is in considerable progress due to new components, e.g., High-Power-LEDs and
light guides, and new sophisticated production techniques. Furthermore, great importance is being attached to the
appearance of front and tail lamps. White High-Power-LEDs have reached a development stage that affords its
reasonable application to low beam headlamps. This challenging illumination function requires sophisticated design
techniques in order to preserve the advantages associated with this source type. Thus, high efficiency and stylish
appearance have to be reconciled, e.g., with the use of freeform surfaces. Beside the demands from manufacturers and
customers, car lamps have to meet several regulations (ECE, SAE, etc.). This contribution describes the illumination
design of a LED-based low beam headlamp using advanced mathematical methods, e.g., 3D-Tailoring, automatic
optimization, and Virtually Reflecting/Refracting Surfaces (VRS). We propose this new surface type with non
conventional reflection/refraction properties as an advantageous design tool for the first layout and for automatic
optimization, as well. For efficiency reasons, special attention will be paid to the creation of the cut-off line without
using additional stops.
Nowadays drivers have to get along with an increasing complex visual environment. More and more cars are on the road.
There are not only distractions available within the vehicle, like radio and navigation system, the environment outside
the car has also become more and more complex. Hoardings, advertising pillars, shop fronts and video screens are just a
few examples. For this reason the potential risk of driver distraction is rising. But in which way do the advertisements at
the roadside influence the driver's attention? The investigation which is described is devoted to this topic. Various kinds
of advertisements played an important role, like illuminated and non-illuminated posters as well as illuminated animated
Several test runs in an urban environment were performed. The gaze direction of the driver's eye was measured with an
eye tracking system. The latter consists of three cameras which logged the eye movements during the test run and a
small-sized scene camera recording the traffic scene. 16 subjects (six female and ten male) between 21 and 65 years of
age took part in this experiment. Thus the driver's fixation duration of the different advertisements could be determined.
There are some interfering elements, which are able to influence the signal functions of a car's rear light. One
of these elements is the sensitivity to external light sources, which is able to affect the intensity of the rear
lamps by the impact of direct sunrays in a flat angle. Recognition of the signals could be made more difficult
or impossible. This effect is called phantom light effect. Today the regulations of the ECE do not contain these
influences. To investigate the meaning of the effects to the traffic safety, there has been a test with a sun
simulator. The task of this test is to measure the luminance of signals from different actual taillights with and
without sunlight. Another part of the investigations are some psychophysical tests involving about 20 persons.
The dimension of phantom light effects at taillights will be quantified by the analysis of the luminance pictures.
With these cognitions some possibilities to reduce the phantom light effect with little changes in the optical
design of taillights will be performed. One example will be shown.
Increasingly, cars are fitted with interior ambient lighting which is switched on while driving. This special kind of
interior light emphasizes the interior design of the car, it makes a car look special and gives the buyers a new option to
personalize their automobiles. But how does ambient interior light influence the driver?
We conducted a series of over 50 tests to study the influence of interior ambient light on contrast perception under
different illumination levels, colors and positions of the illuminated areas.
Our tests show that in many cases the ambient lighting can improve the visual contrast for seeing objects in the headlamp
beam. But the test persons mentioned that the tested brightness looked too bright and that they felt glared. The measured
values instead proved that no disability glare exists. Therefore, provided that the drivers can adjust the intensity of the
ambient light to avoid glare, the ambient light has no negative effect on the drivers' contrast perception.
Actual studies show that 40 % of all accidents occur at night, but the part of the drives during the night represent only
20 % of all drives . So the risk potential to be involved in an accident at night is almost three times higher in
comparison to daytime.
A headlamp is primary used to illuminate the road. Secondary the signal aspect is an identifying feature for other road
users. As simple as these tasks seem to be, it is not easy to perform it in every situation because of environmental factors.
Especially the weather conditions, but also the type of road and the traffic density causes difficulties. The ambition of the
design of a headlamp is an adaptive system which is able to adjust on various factors to perform these tasks.
In many cases there are already technical possibilities to realise new adaptive concepts, but up to now only a few cars are
equipped with these technology. An example is the levelling system. Every modern car has a manually static or an
automatically static levelling system. But because of the vehicle dynamics and the vertical road geometry it would be
advisable to integrate an automatically dynamic levelling system. This System is currently used in the cars of the upper
class. It would increase the road safety if this technology would be integrated in every car.
This study describes the requirements for modern headlamps, discusses already existing systems and shows the technical
possibilities to realise new concepts.
The application of ultra bright monochromatic and white High-Power-LEDs in the range of automotive lighting systems
is now state of the art. These LEDs offer new possibilities in optical design and engineering within different fields of
automotive lighting, e.g., tail lamps, signal lamps, headlamps and interior lighting.
This contribution describes the process of the optical design of an automotive LED tail lamp based on a practical
example. We will elaborate the principal geometric approach, the radiometric conditions and the optical design by using
standard and advanced mathematical optimization methods. Special attention will be paid to the following topics:
efficient light coupling from the LED into the optical device, adaptation of the illuminance and optimization with respect
to the requirements from SAE/ECE regulations.
It will be shown that the development of LED-lamps requires the complex interaction of several factors. The challenge
for the optical designer is to fulfill the technical demands while also considering the appearance of the final product
desired by the customer. Further design specifications emerge from the electrical and thermal layout of the lamp.
The Light Technology Institute conducted an investigation among more than 300 car drivers, 60 truck drivers and 40 bus drivers. We found out that more than 60 percent feel that the greatest problem in driving at night is glare.
In theory, a car of today does not cause glare problems. However, in practice, most people feel glared. Consequently, technological improvements have to be made regarding the development of headlamps that will not glare. Another approach is to introduce more and better night vision systems to enhance drivers' sight with today's headlamps.
In the recent years LEDs became the standard light source for the dashboard, instrument panel and switches in automobiles. In the near future LEDs will bring ambient interior light functions into the vehicle. Advantages of the LEDs are a small installation space, low heat dissipation, the long lifetime and, with Multi-Color-LEDs, the possibility of color tunability. Ambient lighting of door surfaces, floor space and roof liner is beneficial, because it improves drivers orientation and thereby the driving safety.
However the optimal parameters of color and brightness are not known yet. An investigation of the Light Technology Institute follows this question and presents within this framework, how the choice of the ambient lightings color and brightness affect drivers contrast vision.
The rearward signal aspect consists of lights with different colors. With standard technics these signal lights are located at different places. With new technics it is possible to build signal lights with different colors together in one place. The signals overlap. In experiments at the University of Karlsruhe we studied the dependency between reaction time and overlap of signal lights. We can see, that the total overlap from a yellow turn signal and a red brake signal will increase the reaction time. The increase depends of the ratio between the luminance of the turn indicator signal and the luminance of the brake signal. With a ratio from one to one (best case with minimal increase) we found an increase of 300 milli seconds.