| 摘要 |
PURPOSE:To inform a driver of circumstances around a car immediately after entering a tunnel, by operating a detecting device detecting anything unusual around the car just before entering the tunnel, while giving warning to the driver through a detected signal out of the detecting device. CONSTITUTION:A driver switches on a tunnel switch 1 just before entering a tunnel. If so, a microcomputer 8 compares a light signal of a tail lamp of a preceding car and a distance signal from ultrasonic transmitting and receiving circuits 3 and 4 to a tunnel side face T to be inputted from a photosensor 2 with each threshold value. Then, the microcomputer 8 operates a speaker 7 if a car- to-car distance with the preceding car or a distance up to the tunnel side face T unusually becomes shortened. Operation in this microcomputer 8 takes place for the specified time lone till the driver's eyes grow accustomed to darkness after entering the tunnel. |
