| 摘要 |
PURPOSE:To prevent collosion of a vehicle with an obstacle, by a method wherein, by detecting that a distance to the obstacle attains a set value, the result can be alarmed in a 2-step manner. CONSTITUTION:An ultrasonic wave transmitter for transmitting ultrasonic waves to an obstacle 4 and an ultrasonic wave receiver 2 for receiving reflecting waves therefrom are secured to the rear of a vehicle. A signal received by the ultrasonic wave receiver is amplified by an amplifying circuit 10 and the waveform is shaped by a circuit 7. Distance gate generating circuits 12, 13, and 14 set a distance according to a difference in a time between transmission and reception, and can be set to 0.0-0.5m, 0.5-1.0m, and 1.0-2.0m. Delay circuits 15, 16, and 17 are adapted to serve to increase a set distance. A circuit 18 decides a distance to the obstacle 4, and outputs a switching signal of a delay signal from a distance gate according to a distance to the obstacle 4. A distance to the obstacle is reported to a driver in a way to change the sounding mode of a buzzer according to a distance to the obstacle 4. |
