WARNING DEVICE FOR APPROACH BY ULTRASONIC WAVE

摘要

PURPOSE:To give an alarm when an obstacle is located within a range of a prescribed distance by using an indication signal wave showing the time when an ultrasonic wave is reflected by a target and returns and an eliminating signal wave capable of eliminating it. CONSTITUTION:An ultrasonic wave generator S, controlled by the output of an oscillator OS, emits an ultrasonic wave to a target B at time O and its reflected wave is received by a receiver R with (t) time delay. The signal of an oscillator SG is gated with a signal obtained by rectifying the received signal to generate a signal between time O and time (t). Further, it is processed to generate an indication signal wave having a negative pulse at time (t). A delay stair step wave form generator DS, on the other hand, generates an eliminating signal wave delayed by prescribed time T and the indication signal wave is gated with the eliminating signal wave. If the eliminating signal wave arrives lagging the indication signal wave (Tt), the indication signal wave is passed to generate an alarm with its negative pulse. Thus, when an obstacle is located within a range of a prescribed distance, the alarm is generated.