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Determining the effects of sharp cut-off lines vs. smooth cut-off lines on glare rating

Löffler, Wendi and Kobbert, Jonas and Kosmas, Kyriakos and Khanh, Tran Quoc :
Determining the effects of sharp cut-off lines vs. smooth cut-off lines on glare rating.
In: IFAL – International Forum on Automotive Lighting, 07-08.03.2017, Shanghai, China. Proceedings of the 5th International Forum on Automotive Lighting (IFAL)
[Conference or Workshop Item] , (2017)

Abstract

In recent years new headlamp developments have made improvements for driver’s safety. Starting from halogen headlamps, the next major step in increasing night time drives, is made by the introduction of HID headlamps. Due to its new design, it is possible to achieve more light for the driver, and by sharpening the cutoff line, it is possible to get more light closer to the horizon without changing the headlamp aiming. In combination with the increased luminous flux this enables detection distances much higher than those achieved with halogen headlamps with smooth cutoff. With the current development of new high resolution LED systems, it is possible to create nearly homogeneous light distributions, thus theoretically creating a perfectly sharp cutoff. While this might result in higher detection distances compared to traditional systems like halogen, HID or even simple LED, road unevenness might also cause much higher glare. This is due to the fact that small changes in vehicle inclination could cause the light beam and by this the cutoff line to be lifted up to and over the eyes of a potentially oncoming driver. At the Technische UniversitätDarmstadt a laboratory study is performed to determine the effect of different gradients in the cutoff of headlamps. For this purpose, a group of test subjects is shown different light pulses that are being varied in duration, peak intensity and shape. Peak intensity is varied from 0.04 lx to 11.28 lx to simulate different headlamp intensities. Durations are chosen from 0,3 to 40 s to simulate different types of road unevenness. All light pulses are selected to form sets with equal exposure rates and to be able to compare between the selected pulse shapes. Two shapes are selected: a triangle and a square, to simulate as explained above, the two extreme possibilities of cutoff lines, smooth and hard.

Item Type: Conference or Workshop Item
Erschienen: 2017
Creators: Löffler, Wendi and Kobbert, Jonas and Kosmas, Kyriakos and Khanh, Tran Quoc
Title: Determining the effects of sharp cut-off lines vs. smooth cut-off lines on glare rating
Language: English
Abstract:

In recent years new headlamp developments have made improvements for driver’s safety. Starting from halogen headlamps, the next major step in increasing night time drives, is made by the introduction of HID headlamps. Due to its new design, it is possible to achieve more light for the driver, and by sharpening the cutoff line, it is possible to get more light closer to the horizon without changing the headlamp aiming. In combination with the increased luminous flux this enables detection distances much higher than those achieved with halogen headlamps with smooth cutoff. With the current development of new high resolution LED systems, it is possible to create nearly homogeneous light distributions, thus theoretically creating a perfectly sharp cutoff. While this might result in higher detection distances compared to traditional systems like halogen, HID or even simple LED, road unevenness might also cause much higher glare. This is due to the fact that small changes in vehicle inclination could cause the light beam and by this the cutoff line to be lifted up to and over the eyes of a potentially oncoming driver. At the Technische UniversitätDarmstadt a laboratory study is performed to determine the effect of different gradients in the cutoff of headlamps. For this purpose, a group of test subjects is shown different light pulses that are being varied in duration, peak intensity and shape. Peak intensity is varied from 0.04 lx to 11.28 lx to simulate different headlamp intensities. Durations are chosen from 0,3 to 40 s to simulate different types of road unevenness. All light pulses are selected to form sets with equal exposure rates and to be able to compare between the selected pulse shapes. Two shapes are selected: a triangle and a square, to simulate as explained above, the two extreme possibilities of cutoff lines, smooth and hard.

Title of Book: Proceedings of the 5th International Forum on Automotive Lighting (IFAL)
Uncontrolled Keywords: glare, de Boer, illuminance, exposure
Divisions: 18 Department of Electrical Engineering and Information Technology
18 Department of Electrical Engineering and Information Technology > Institute for Electromechanical Design
18 Department of Electrical Engineering and Information Technology > Institute for Electromechanical Design > Light Technology
Event Title: IFAL – International Forum on Automotive Lighting
Event Location: Shanghai, China
Event Dates: 07-08.03.2017
Date Deposited: 12 Feb 2018 11:43
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