| 摘要 |
PROBLEM TO BE SOLVED: To obtain a vehicle detector using near infrared light for accurately performing the number measurement and speed measurement of traveling vehicles. SOLUTION: This vehicle detector is constituted of a light emission part 12 driven by a driver part 2 connected to a pulse modulation signal generation part 1, a first light reception part 13 - an (n)-th light reception part 15 for receiving the reflected waves of light radiated by the light emission part 12, a first difference detection part 19 - an (n)-th difference detection part 21 for extracting only pulse components from the output of the first - (n)-th light reception parts 13-15, an absolute level comparison part 37 for detecting the vehicle by A/D converting and level-comparing the output of the first - (n)-th difference detection parts 19-21, an absolute addition value comparison part 38 for A/D converting, adding and level-comparing the output of the difference detection parts 19-21 and a passing speed detection part 39 for detecting the speed of the vehicle from the time difference of reflected light from the vehicle detected in the first light reception part 13 and the reflected light from the vehicle detected in the (n)-th light reception part 15.
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