PURPOSE: To detect the brightness of the visual field in front of an automobile in an excellent state by providing an opening part to a dashboard, fitting a polarizing prism thereto, and arranging the illuminance sensor at its rear side.
CONSTITUTION: The opening part 12 is formed in a surface of the dash board 11 which faces the windshield, a step part 12A is formed at the upper end part of the opening part 12 as a prism storage part and the polarizing prism 13 having a plane front surface and a prism cut rear surface is fitted thereto, and the illuminance sensor 14 is arranged at its rear side. Then, the prism 13 is so formed that light from before the automobile when incident on the prism surface 13A at an angle θx is deflected and strikes the photodetection surface of the sensor 14 at right angles. Then, incident light having an angle θin to an axial line l1, on the other hand, is refracted by the top surface and refracting prism surface and polarized at right angles to the top surface of the dashboard 11, and incident on the sensor 14 as vertical light. Consequently, the directivity of the sensor 14 is improved and the front visual field of the automobile and the detection direction of the sensor are made coincident with each other.
TSUCHIYA RYOICHI
KIKUCHI AKIRA
OKAZAKI KUNIO
OBARA HIFUMI
TANABE TORU
YAMASHITA SATOSHI
STANLEY ELECTRIC CO LTD
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