| 摘要 |
PURPOSE:To recognize the presence or absence of collision of a vehicle against an obstruction surely beforehand by transmitting ultrasonic waves toward the obstruction and detecting said presence or absence from the presence or absence of any alarm signal from an alarm device produced in accordance the reflected ultrasonic waves therefrom. CONSTITUTION:An ultrasonic wave transmitter and receiver 50 generates ultrasonic waves repeatedly by responding to the respective ultrasonic wave signals from a switching circuit 40 and transmits the same toward the front of a truck 10. When in such a state the ultrasonic waves from the receiver 50 are reflected by an obstruction 11, the circuit 40 receives the backward advancing ultrasonic waves and applied the same to a driving circuit 60 under annihilation of the trigger pulses from a trigger pulse generating circuit 20. The received signal thereof is amplified by an amplifier 64 and is detected with a detector 65, then the signal is applied to a comparator 67. On generation of the high level signals from the comparators 67 and a comparator 63, an alarm device 70 generates alarming sounds intermittently in response to the driving signal from the circuit 60. |
