ULTRASONIC RECEIVER AND OBSTACLE DETECTOR

摘要

PURPOSE:To enable the operation of an air bag beforehand by detecting obstacles by an ultrasonic wave in all directions around an automobile to predict collision on the side thereof in particular. CONSTITUTION:An ultrasonic transmitter 20 is provided on an automobile to transmit an ultrasonic wave 4 and a rubber-like elastic body 11 in which electroconductive particles are dispersed is mounted on the entire circumference of the automobile in such a manner as to serve as molding concurrently. A voltage is applied to the rubber-like elastic body 11 with a conversion circuit 15 and an ultrasonic vibration is received to detect the reflected wave 5 from an obstacle by converting a changing electric resistance into a voltage signal. A distance is determined with a distance calculator 24 from a difference in time between the transmitting and receiving of the ultrasonic wave and a relative speed is obtained with a relative speed calculator 26 from a difference in frequency between transmitting and receiving thereof. Time is determined previously up to a collision with a collision time calculator 27 from the results. When the time is below a specified value, an air bag 32 is opened by a command of an air bag operation commanding device 28.