| 摘要 |
PURPOSE:To have safe drive backward by allowing the indicating means to give a distance, which is a certain value smaller than the sensed actual distance to any obstacle behind, when the backward speed of the car exceeds the reference value. CONSTITUTION:When the shift lever is put in the ''back'' position in order to drive the car backward, the ''back'' switch 5 is turned on to set a transmitter circuit 3 under control with the aid of a micro-computor 8, and ultrasonic pulses are cast from an ultrasonic wave sender 1 backward the car. When these pulses are reflected by an obstacle and received by a receiver circuit 4 through a wave catcher 2, the micro-computor 8 will get the distance data instead of the timer data as fed earlier. At this time, the car speed based on the output from the car speed sensor 7 is placed on comparison with the reference value a, and if S>a, the above-mentioned distance data undergoes a subtraction treatment to be converted into a distance data which gives a certain value smaller than the actual distance to the obstacle. Either of the lamps 10a-10c is lighted on the basis of this data obtained. |
