ADB Rating Systems, from entry version up to high resolution
• E.O. Rosenhahn, Marelli Automotive Lighting
The evaluation of performance of traditional headlamps was defined in the past by the group CIE-TC 4-45 particularly by the measure of the range in three zones with the isolux 1, 3, and 5 lux.
But ADB systems have specific beam patterns and no internationally agreed system is currently existing. E.O. Rosenhahn is proposing a system inspired by the procedure defined by CIE-TC 4-45 but adapted to ADB. Some could consider the maximum intensity or the resolution or the gradient of the vertical cutoff as important for the evaluation of performance. But finally, the most important for safety is the range down the road, proposed as the main criteria for the rating.
One of the main interests of ADB is the good perception of pedestrians. The average height being 1.77 m for male and 1.64 m for female, the height of 1.5m is chosen for measurements of the beam. The different situations considered by the regulation ECE 123 for instance 200 m preceding car or on-coming car at 50 m, 100 m, and 200 m are used and the points with 1, 3, and 5 lux from the left side and the right side of the road are measured.
The average of these distances is the base of the rating. The graph on the right is showing examples of measures of entry, typical and high end ADB.
The complete headlamp rating with LB, HB, ADB weighted respectively 30%,30% and 40% can be done with the different levels Standard, Good, Advanced, Premium, Premium+.
To be retained: The target of this proposal is to introduce a reproducible assessment method for ADB systems with acceptable efforts providing a representative and easy to read result. Formulated with Darmstadt University, it will be available in 2021.
Stress Reduction with Monolithic
• Hiroyasu Onuki, Ichikoh
H.Onuki proposed an original method for the evaluation of the interest of ADB systems through a medical approach with the measurement of drivers’ stress.
Three specialized parameters, SD1/SD2 (Activity balance of sympathetic and parasympathetic nerves), APEN (index of heart regularity), RMSSD (short term direct stress) were monitored with ten drivers using three types of beams: Low beam, Matrix beam 11 segments and the new High definition Valeo-Ichikoh system called “Monolithic”.
It appears that Matrix beam is giving 36% less stress than simple Low beam, and “Monolithic” is giving a complementary 36% reduction of stress. The “Monolithic” ADB system will include 2,5K, 4K or 20K pixels.
This improvement for stress is supposed due to the high precision, high homogeneity, and high fluidity of the “Monolithic” beam.
This stress reduction could improve time reaction and so safety as established by previous studies.
To be retained: This study is so consolidating the interest in safety and comfort of good beams particularly ADB HD.
Possibilities of next generation high-definition modules
• Gerald Boehm, ZKW
The target of the presentation is to analyse the possibilities of improvement of µLEDs systems.
First systems under development with µLEDs could have 15000 pixels, to be compared to 1,3 Mio pixels of DLP.
This resolution is enough for a good ADB, but not so good for projection. In fact, with 15K, we can have a 20° horizontal FOV and 6° V FOV. Vertically that means 60 lines, including 20 above the horizon, and so 40 lines on the road, not enough for projection.
An improvement could be to have 130 000 pixels with the same FOV. In that case, the foreground projection with 120 lines is giving a good precision to projected symbols.
But for a good projection, it not enough to have a µLED source with 130 000 pixels, the optical system must be also improved. A multi-lens system is so necessary giving precise imaging and good contrast, but at the price of complexity, cost and lower efficiency and intensity.
Another direction for improvement is the increase of the field of view. Today with 24° H FOV and 6° V FOV, the installed power is already at 150W while the average used power is at 50W, so with a system using “efficiency” of 30%.
With the same pixel density than the previous 15K system with the increase of H FOV to 100° and the V FOV to 20°, the chip size would be 200 000 pixels and the installed power 2000W while the real used power would be 65W. So, with a system using efficiency of 3%.
A full digital headlamp with levelling aiming would even need 115° H FOV and 35° V FOV with 400 000 pixels. The installed power should be 4000W while the real power used would be 65W, so with a system using efficiency of only 1,6%.
To be retained: a resolution of 100 000 pixels will be a reasonable compromise for precise projection and cost, but the increase of FOV will need especially important decrease of cost of LEDs before implementation.
Evolution of ADB – Stanley never end the evolution of headlamps
• Yasushi Yatsuda, Stanley
Stanley presented an LCD version of ADB, that would be a step before in the future Laser Scan ADB and later RGB ADB.
A specific technology was developed called PBT as Pure Black Technology.
First Stanley has defined the definition necessary to ensure a good safety. As 95% of accidents are on straight roads, this situation was consequently considered. The LCD pitch was after defined in relation to the horizontal field of view as shown on the right.
The LCD system is giving sharp cut-off and more than 100 luminance gradations. The global efficiency is 30%.
Stanley has chosen LCD for the following advantages compared to LED array: independence of segments (no superposition), segments can be thinner without extra cost with high contrast and possibility to control brightness, the shape of segments is flexible authorizing curve segments. Road projection for instance side lines can also be realized with LCD.
Stanley is considering that this system could be especially useful for motorcycles in curves. In that case, there would be no camera, a simple sensor directly giving the inclination to allow the horizontal stability of the beam.
A complementary argument for LCD is style freedom as these systems can be adapted to different shapes of headlamps.
To be retained : LCD is so representing another interesting solution in parallel to DLP and µLED in the HD ADB race