| 摘要 |
<p>PURPOSE:To reduce the number of light projectors and light receivers and to make the maintenance easier, to improve the reliability, to reduce the cost of the title detector by including optical paths perpendicularly crossing a railroad crossing road and optical paths obliquely crossing rails in the optical path from a light projector to a photodetector through light reflectors. CONSTITUTION:A light projector 4, a photodetector 5, and light reflectors 61, 62, and 63 are arranged so that the optical path from the light projector 4 to the light receiver 5 through the light reflectors 61, 62, and 63 contain optical paths perpendicularly crossing a railroad crossing road outside the rails 1 and 2 and optical paths obliquely crossing the rails 1 and 2. Therefore, when the pair of a light projector 4 and light receiver 5 is provided, the optical paths necessary for detecting an obstacle in the railroad cross can be formed. Thus an obstacle in the railroad crossing can be detected with high reliability at a low cost with less numbers of the light projectors 4 and light receivers 5.</p> |
