| 摘要 |
PURPOSE: To preliminarily prevent an accident of colliding a guard rail or the like by expecting the radius of the curve of the road on which a vehicle travels from the arrangement of a subject to be measured, and judging the collision of the vehicle relative to the subject to be measured from the relationship between the expected radius of the curve of the road and the vehicle speed. CONSTITUTION: A subject to be measured is irradiated with the pulse-shaped near- infrared ray from a light irradiating part 1 according to the pulse signal to be generated in a pulse driving part 3. The reflected light from the subject to be measured is received by a light receiving part 5. The period of time from the irradiation to the reception is converted into the voltage by a time/voltage converting part 7, and this time/voltage signal is converted into the digital value by an A/D converting part 9. The vehicle speed to be detected by a vehicle speed detecting part 25 is converted into the digital value by an A/D converting part 9. The time between the irradiation of the near-infrared ray converted into the digital value from the light irradiating part 1 to the reception by the light receiving part 5 is operated as the distance to the subject to be measured by the light speed and the vehicle speed by an operation processing part 11, and the possibility of collision is judged and an alarm is given.
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