| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve the reliability for detecting an obstacle in railroad crossing. SOLUTION: Two sets of light transmitter 41 and light receiver 42 are maple to corresponding each other constitute a bi-directional light path. Therefore, even if either one of the light transmitter 41 and light receiver 42 in the bi- directional light oath fails and one of the bi-directional paths becomes unable to detect it does not become immediately impossible to detect obstruct, and the reliability for improving the detection of the obstacle is improved, and at the same time, detection light is sunely transmitted to the light receiver 42 by transmitting the detection light from a pair of transmitters 41 from nearly the same position to one receiver 42, thus further improving the reliability for detecting the obstacle.</p> |
