Online ISSN : 1349-838X
Print ISSN : 0019-2341
ISSN-L : 0019-2341
Volume 91 , Issue 5
Showing 1-3 articles out of 3 articles from the selected issue
  • Miyoshi Ayama, Yudai Fujita, Jun Suzuki, Yoshifumi Kawaguchi, Shinichi ...
    2007 Volume 91 Issue 5 Pages 251-257
    Published: 2007
    Released: July 10, 2007
    To assist night-time driving, night vision systems (NVSs) present the image of forward visual field taken with an infrared/near-infrared camera to a driver. We investigated whether such systems detect a visual target (i.e., a pedestrian, a road sign, or obstacles) faster than conventional low-beam forward lighting does. Our results showed the NVS is significantly faster. We also examined various sizes and positions of the HUD presenting the NVS image and determined the appropriate image size and position of the HUD for the NVS. An image, 6(H) × 4.7(V) degrees in visual angle, presented in the lower front of the driver showed the best scores in subjective evaluations.
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  • Yoshio Watanabe, Hideto Kurimoto, Takayuki Nitta
    2007 Volume 91 Issue 5 Pages 258-265
    Published: 2007
    Released: July 10, 2007
    One-dimensional model for a barrier discharge lamp is investigated. The plasma coefficients employed in the model were determined by the trial-and-error method. Using this model, fairly good agreements are obtained between the calculated discharge current waveforms and the measured those for several applied voltage waveforms. The distributions of electron density, ion density, and the electric field at each phase of the discharge cycle are obtained by this model. Then the mechanism of current-waveform formation is discussed. In the case of the applied voltage of sinusoidal, triangular, and trapezoid waveforms, the model shows that abrupt ionization in the space charge layer on the wall takes place during the current increasing phase. However, such ionization would not take place during the current decreasing phase. These results agree with the experimental results.
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  • Hideki Yamaguchi, Hiroyuki Shinoda
    2007 Volume 91 Issue 5 Pages 266-271
    Published: 2007
    Released: July 10, 2007
    In previous study, we defined the border luminance as space brightness and investigated what determines border luminance in a real environment. We undertook a second study to confirm that perceived brightness of a room is determined solely by border luminance. We also examined the correlation between change in the magnitude of space brightness and change in the border luminance. To investigate these two points, we measured space brightness using three methods: magnitude estimation, space-brightness matching, and border-luminance adjustment. We found that, the border luminance is the same even though the illuminance of the room or the configuration of interior surface reflectance is different, the matched illuminance is the same. The brightness value obtained using the magnitude estimation method was proportional to the 0.56-th power of the border luminance. Our results clearly show that space brightness can be evaluated quantitatively using border luminance adjustment even if the brightness cannot be measured using the horizontal illuminance. Therefore, measuring the border luminance is an effective way to supplement existing photometric systems.
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