ULTRASONIC DETECTOR FOR OBJECT

摘要

PURPOSE:To obtain an accurately operating ultrasonic detector for an object by arranging a signal discrimination circuit so as to made a decision that a sample does not exist within a specific range only when a receiving section does not detect an ultrasonic signal in the ultrasonic wave sensible time range. CONSTITUTION:An ultrasonic wave oscillation circuit 1 generates a series of ultrasonic pulse trains a1 and a2 with a fixed time range at a certain cycle. An output gate circuit 2 repeats opening or closing synchronizing the ultrasonic pulse trains in such a manner as to open only at a time interval necessary for passage of pulses a1, a2... unless it receives a special gate closing command signal from a detection circuit 9. On the other hand, the gate closing command signal from the detection circuit 9 is received to check the opening of the gate which will take place immediately after the reception thereof. An input gate circuit 8 repeats the opening or closing at the same cycle as the output gate 2 with the gate opening time so determined to allow the passage of reflected ultrasonic pulses delayed by time required for return thereof to a receiver 6 after the pulses emitted from a transmitter 4 are reflected on a smalple at the specific position.