| 摘要 |
PURPOSE:To surely detect even a container car or the like as one vehicle by providing an output correcting means which outputs a signal indicating the presence of a vehicle within a set time after reception of the wave reflected from the vehicle in response to the auxiliary reflected wave received by an auxiliary transmission/reception part. CONSTITUTION:A main ultrasonic transmission and reception part 4 which transmits an ultrasonic to an about center on the road surface and receives the ultrasonic reflected from the road surface, an output means 29 which outputs the signal indicating the presence of a vehicle in response to the wave reflected from the vehicle, an auxiliary ultrasonic transmission and reception part 5 which receives the ultrasonic reflected from the road surface, and an output correcting means 29 which causes the output means to output the signal indicating the presence of the vehicle with the set time after reception of the wave reflected from the vehicle in response to the auxiliary reflected wave in case of absence of the wave reflected from the vehicle are provided. Consequently, the output correcting means outputs the signal indicating the presence of the vehicle to the output means even if the pole part of a pole trailer passes a detection zone and the wave reflected from the vehicle is not received, and the pole trailer is detected as one vehicle without breaking the signals indicating the presence of the vehicle by the pole part. Thus, all vehicles are surely detected.
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