Development of Liquid Crystal Day and Night Mirror for Automobiles

Aoki

et al. 1995

This study was part of a series of studies on variable-reflectance rearview mirrors. Previous work included laboratory studies of human visual performance, field collection of photometric data, and mathematical modeling of the visual benefits of variable-reflectance mirrors. We extended that work in this study by collecting photometric and human-performance data while subjects drove in actual traffic. Three mirror conditions were investigated: (1) fixed-reflectance mirrors in the center and driver-side positions, (2) a variable-reflectance mirror in the center with a fixed-reflectance mirror on the driver side, and (3) variable-reflectance mirrors in both positions. The fixed and variable reflectivities were produced by the same mirrors by overriding the circuitry that normally controlled reflectance in the variable mode. Results indicated that variable-reflectance mirrors provided a substantial reduction in discomfort glare without a measurable reduction in subjective ratings of rearward seeing ability. They did not cause major improvements in forward seeing (in agreement with previous laboratory and modeling results). The present study is inconclusive with respect to the benefits of a variable-reflectance driver-side mirror relative to a fixed-reflectance mirror with 50-percent reflectance. The reason for this is that the particular driver-side mirror used in this study became noticeably green in the lowreflectivity state, and thus low reflectivity was confounded with a color change. The effect of the driver-side mirror should be clarified by further research.

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Section: Introductionmentioning

confidence: 99%

On-the-Road Visual Performance with Electrochromic Rearview Mirrors

Aoki

et al. 1995

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“…In a recent survey, 33 percent of respondents reported reducing or forgoing the use of the antiglare setting because of inability to see to the rear (Flannagan & Sivak, 1990). Also, several studies, based on a variety of methods, have recommended reflectivity levels higher than 4 percent as compromises between visibility and glare protection (Mansour, 1971;Olson, Jorgeson, & Mortimer, 1974;Ueno & Otsuka, 1988).…”

Section: Introductionmentioning

confidence: 99%

Rearview Mirror Reflectivity and the Quality of Distance Information Available to Drivers

Battle

et al. 1993

UMTRI-92-46 la w a~ hit NO. ( m s ) 11. Cona Burl No. 13. T y p . o f~M d P r i o d C o m d S P M n g AOlcKy Co* 16. AbrtnclIn two experiments, we examined the possibility that rearview mirror reflectivity influences drivers' perceptions of the distance to following vehicles. In the first experiment, subjects made magnitude estimates of the distance to a vehicle seen in a variable-reflectance rearview mirror. Reflectivity had a significant effect on the central tendency of subjects' judgments: distance estimates were greater when reflectivity was lower. There was no effect of reflectivity on the variability of judgments. In the second experiment, subjects were required to decide, under time pressure, whether a car viewed in a variable-reflectance rearview mirror had been displaced toward them or away from them when they were shown two views of the car in quick succession. We measured the speed and accuracy of their responses. Mirror reflectivity did not affect speed or accuracy, but it did cause a bias in the type of erors that subjects made. With lower reflectivity, there was an increase in errors in which displacements that were actually nearer were judged to be farther, and an approximately compensating decrease in errors in which displacements that were actually farther were judged to be nearer. We interpret these results in terms of their implications for optimal reflectivity levels of rearview mirrors. The findings that reflectivity did not affect variability of magnitude estimates, reaction time for distance discrimination, or accuracy of distance discrimination suggest that the quality of distance information should not be considered a major factor in determining optimal reflectivity levels. However, these results should be interpreted within the limits of the methods of this study. Furthermore, the effect of reflectivity on the central tendency of magnitude estimates of distance should be explored further.

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Nighttime Effectiveness of Rearview Mirrors: Driver Attitudes and Behaviors

1990