| 摘要 |
PURPOSE:To alarm and display the existence of a rear object when a car is driven in reverse gear by providing a detection sensor of the rear object, alarm display of the existence of the object, damping status detection means and so on. CONSTITUTION:When transmission is selected in a rear position and the power switch of a control circuit 4 is closed, initialization is performed and ports P1 and P4 are set to logic 0. A flip-flop is reset and the timer of a microcomputer 41 is zero-cleared and time is set to t=0. Then the port P1 between t=0 and t= T1 is set to logic 1 and a transmitter 1a sends and issues ultrasonic waves 5a is excited by the oscillation frequency of an oscillator circuit 42 and then wits for time when the time T2 corresponding to the detection length against the preset rear object 6 is reached. Furthermore, if reflected waves 5b are received by the time t=T2 after the ultrasonic waves 5a are issued, the object is assumed to exist in this preset length and a preset alarm tone sounds from a speaker 2. |
