| 摘要 |
PURPOSE:To achieve a reduction in the cost with the saving of the number of ultrasonic sensors used, by arranging a plurality of reflecting plates in the course of an ultrasonic beam in such a manner as to project freely. CONSTITUTION:A plurality of reflecting plates 3a, 3b... which bend an ultrasonic beam at the right angle are arranged side by side along the course C of an ultrasonic beam to project into or retract freely from the course C with reflecting plate drivers 4a, 4b... at almost 45 deg.. A transmitting/receiving circuit 2 and the reflecting plate drivers 4a, 4b... are controlled with a control circuit 5 and the reflecting plates 3a, 3b... refract from the course C starting from the one closer to an ultrasonic sensor 1 or project into the course C sequentially from the one farther therefrom. With each action, an ultrasonic beam is outputted from the ultrasonic sensor 1 to measure the distance to an object 6 via the reflecting plates 3 from the ultrasonic sensor 1. Further, distances to the reflecting plates 3a, 3b... from the ultrasonic sensor 1 are subtracted from measured values to calculate distances to the object 6 from the reflecting plates 3a, 3b....
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