| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a critical hindrance annunciator capable of securely receiving data, even in the case where the dispersion of data due to the variation in temperature is caused. SOLUTION: When any of optical fibers 131 to 13n is cut, each of the optical sensor parts 21 to 2n outputs a hindrance detecting signal. The respective optical sensor parts 21 to 2n are arranged on the side of a railway track 5, 6 along its length at intervals. Both ends of each optical fiber 131 to 13n are connected between a pulse light outgoing route 11 and a pulse light return route 12. An optical signal sending part 3 sends a pulse light P1 to the light sending end O of the pulse light outgoing route 11. An optical signal detecting part 4 has a light receivable time window W for receiving the pulse light P21 to P2n being supplied through the pulse light return route 12. The time length T of the light receivable time window W corresponds to the geographical distance of the optical sensor parts 21 to 2n.</p> |
