| 摘要 |
PURPOSE:To make it possible to detect the presence of an obstacle even at the time when the distance between a following car and the obstacle exceeds the measuring range, by making it possible for a wave-receiving unit to receive an ultrasonic wave which is transmitted from a wave- transmitting unit of a preceding car and reflected by the obstacle and also to drive a projector. CONSTITUTION:The signal of a pulse width 2T transmitted from the wave-transmitting unit 8 of the following car 2 is received by the wave-receiving unit 5 of the preceding car 1 and the ultrasonic wave of a pulse width 1T is transmitted from the wave-transmitting unit 3, and this wave is received by the wave-receiving unit 10 and measured by an operation processing circuit 30 to determine the distance between these two cars. In case if the distance between the following car 2 and the obstacle 11 exceeds 25 meters, the signal from the wave-transmitting unit 3 is reflected by the obstacle 11 and received by the wave-transmitting unit 5, to operate the projector 12. The modulated lights signal is received by a light receiver 15 to make interruption to the operation processing device 30 for determination of the distance between the following car and the obstacle 11. And therefore, it is possible to detect the distance between the car and the obstacle irrespectively of the distance between the following car and the obstacle. |
