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Technical Paper

The Smart Headlamp System with Variable Low-Beam Pattern

2001-03-05
2001-01-0854
The present study was designed to investigate the advantage of a new headlamp system. This so-called smart headlamp system involves headlamps with variable beam patterns. We analytically investigated visibility for the driver and glare to other road users under several conditions including curves and straight roads. We conclude that the smart headlamp system provides overall benefits.
Technical Paper

Fog Lamps: Frequency of Installation and Nature of Use

1997-02-24
970657
The goal of this study was to provide information about the frequency of installation and use of fog lamps. Two surveys were performed. In the first one, installation of fog lamps was estimated by a survey of parked vehicles in two iarge shopping centers. The second survey studied the usage of fog lamps during daytime and nighttime, under clear, rainy, or foggy conditions. In this survey, an observer in a moving vehicle noted the types of lamps that were energized on the fronts of oncoming vehicles, and whether fog lamps were installed at all. The main findings are: (1) The best estimate of the current frequency of installation of fog lamps in southeast Michigan is about 13%. (2) During daytime, the usage of fog lamps increased with deterioration in atmospheric conditions, with the usage reaching 50% of all installed fog lamps during moderate-to-heavy fog.
Technical Paper

A Field Study of Distance Perception with Large-Radius Convex Rearview Mirrors

1998-02-23
980916
One of the primary reasons that FMVSS 111 currently requires flat rearview mirrors as original equipment on the driver's side of passenger cars is a concern that convex mirrors might reduce safety by causing drivers to overestimate the distances to following vehicles. Several previous studies of the effects of convex rearview mirrors have indicated that they do cause overestimations of distance, but of much lower magnitude than would be expected based on the mirrors' levels of image minification and the resulting visual angles experienced by drivers. Previous studies have investigated mirrors with radiuses of curvature up to 2000 mm. The present empirical study was designed to investigate the effects of mirrors with larger radiuses (up to 8900 mm). Such results are of interest because of the possible use of large radiuses in some aspheric mirror designs, and because of the information they provide about the basic mechanisms by which convex mirrors affect distance perception.
Technical Paper

A Market-Weighted Description of Low-Beam Headlighting Patterns in the U.S.

1998-02-23
980317
This study was designed to provide photometric information about current U.S. low-beam headlamps. The sample included 35 low-beam headlamps manufactured for use on the 23 best-selling passenger cars, light trucks, and vans for model year 1997. These 23 vehicles represent 45% of all vehicles sold in the U.S. The lamps were purchased directly from vehicle dealerships, and photometered in 0.5° steps from 45° left to 45° right, and from 5° down to 7° up. The photometric information for each lamp was weighted by 1997 sales figures for the corresponding vehicle. The results are presented both in tabular form for the 25th-percentile, the median (50th-percentile), and the 75th-percentile luminous intensities, as well as in graphical form (for the median luminous intensities, and median illuminance values reaching the road surface). The information is presented in aggregate form, as well as broken down by vehicle type and light source.
Technical Paper

Color Perception and Recognition under Automotive Headlight with LED

2007-04-16
2007-01-1036
In the near future, the LED headlamps will be available in the market by improvement of the technique. There are some methods that can produce white light using LEDs. Probably, we think most generally method is using blue LED and yellow phosphor. But, spectral power distribution (SPD) of this type of white LED is much different from traditional white light that is produced by halogen or HID. This type of the white LED has poor spectral power in long wavelength region and much spectral power in short wavelength region. So, the white light by LED might have color-rendering problem. On the assumption that automotive head lamps with white LED and halogen, the human color perception and recognition under wide range of illuminance conditions from photopic to mesopic was measured, using categorical color naming method and elemental color scaling method. As the result of this measurement, stability of categorical color naming was lower under lower illuminance level with both light sources.
Technical Paper

A Recommendation for the U.S. Lower-Beam Pattern for Visual/Optically Aimable Headlamp

2002-03-04
2002-01-0260
Headlamp aiming is one of the most important factors of lighting performance. In the U.S, visual/optically aimable headlamps must have a certain cut off vertical gradient for adjustment, and should conform to photometric requirements at its position. The manufacturer can choose a vertical cut off position either on the left side (VOL) or the right side (VOR) of the optical axis for particular headlamp system designs. However regulations aren't clearly written on headlamp aiming position on the vehicle. Even if the headlamp aiming is positioned correctly on the vehicle, the beam may cause discomforting glare to oncoming or ongoing road users, depending on the height of the lamp on the vehicle. This could also cause safety problems. The discomforting glare to oncoming drivers and the mirrors of ongoing traffic is compared between VOL and VOR of each headlamp height. This paper recommends optimum Lower-beam patterns at each headlamp height.
Technical Paper

The Low-Beam Design Guidelines for The U.S. Market

2001-03-05
2001-01-0459
The present study was designed to investigate the customer preferences related to headlights, as measured by J.D. Power and Associates 1998 Initial Quality Study (IQS) - (“Headlights not aimed properly” question). We investigated beam patterns that ranged from high to low customer preference. As a result of our investigation, we have developed guidelines for desirable beam patterns for the U.S. market in terms of the sharpness of the cutoff, the foreground brightness, and the total flux value.
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