| 摘要 |
PURPOSE:To provide only one ultrasonic vibrator to be used, by continuously transmitting an ultrasonic wave from an ultrasonic vibrator and detecting moving matter from the change in the amplitude of the current flowed to the ultrasonic vibrator. CONSTITUTION:When matter is moving, the magnitude and phase of the reflected wave R received by a vibrator 1 change and, as a result, the amplitudes of the signals generated at both terminals of a resistor 3 change corresponding to the movement of the matter. By this method, the detection signal corresponding to the change in the amplitudes of the signals generated at both terminals of the resistor 3 appears in the output of a detector 5 and amplified by a band amplifier 6 and, when the amplified output signal is compared with predetermined voltage by a comparator 7, the pulse line corresponding to the movement of the matter is outputted to an output terminal 8. By this method, the moving matter can be detected by using one ultrasonic vibrator.
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