| 摘要 |
<P>PROBLEM TO BE SOLVED: To eliminate the influence of a low frequency optical noise to prevent the mutual interference with an adjacent crossing and additionally to make a detector small to reduce the restriction in installation. <P>SOLUTION: The crossing obstruction detector includes: light emitters 1a to 1e modulating carrier waves, driving light emitting elements, and emitting modulated waves with an intermittent period; and light receivers 2a to 2e receiving lights from the light emitters 1a to 1e, converting it to voltages, and taking out modulated wave components, converting them to direct currents, and outputting them. The detector raises the frequencies of the carrier waves and the modulated waves of the light emitters 1a to 1e, and prevents erroneous detection due to the low frequency optical noise such as HID lamps to surely detect the crossing obstruction such as vehicles. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
