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AssigneeNgk Spark Plug Co., Ltd.
InventorsKeigo Banno, Hideki Ishikawa, Yoshikuni Sato, Noboru Ishida, Takafumi Oshima
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An ultrasonic-wave propagation-time measuring method and gas concentration sensor are disclosed in which a reception wave which has been transmitted and received by an ultrasonic element 5 is subjected to full-wave rectification in order to obtain a full-wave-rectified wave, which is then integrated by an integration circuit 37 to obtain an integral value. A peak value of the integral value is held by a peak-hold circuit 39. As to detection of gas concentration, a threshold-level calculation section 21e sets a reference value on the basis of the peak value, and a point in time when the amplitude of a reception wave having undergone full-wave rectification is judged by a comparator 43 to have reached the reference value is regarded as an arrival time. Subsequently, a gas concentration is determined on the basis of a period between the emission time and the arrival time.
An ultrasonic-wave propagation-time measuring method in which an ultrasonic wave is transmitted by use of an ultrasonic element, a reflection wave of the transmission wave is received as a reception wave by use of the same ultrasonic element or a different ultrasonic element, and a period of time between transmission of the ultrasonic wave and reception of the reception wave is measured as a propagation time, the method comprising:
Dependencies are inferred from the claim text.