| 摘要 |
PROBLEM TO BE SOLVED: To provide a distance measurement method that is suited for measuring, especially the distance between vehicles, and to provide a start/stop control device that has a simple structure and can be manufactured inexpensively by using the distance measurement method. SOLUTION: A laser beam is emitted from a light projection part 2 and at the same time, a scanner part 3 for reflecting the laser beam is rotated according to a signal from a control part, and a laser beam is projected for scanning in a specific light projection range. At this time, the control part detects the rotary angle of the scanner part 3 and outputs an angle signal. When a reflector (recursive reflector) exists in the light projection range, a reflection laser beam that is reflected from the reflector enters a light reception part 4 and a light reception signal is outputted from a signal-processing part 5. A CPU 6 detects the arrival direction of the reflection laser beam according to the angle signal from the control part at this time. Then, the CPU 6 judges the angle of the two reflection laser beams for the reflection laser beam from the two different directions and outputs a control signal for starting or stopping its own vehicle based on the angle.
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