| 摘要 |
PURPOSE:To enable the measuring of the height of an object to be measured accurately from a reference measuring surface, by arranging a memory circuit for storing counts of a counting circuit and a subtracting circuit for subtracting counts of the counting circuit from a memory value of the memory circuit. CONSTITUTION:A signal wave formed with a first oscillation circuit 10 is modulated 12 using a carrier formed with a second oscillation circuit 11 and the modulation signal is converted into an ultrasonic wave 9 with an ultrasonic wave transmitter/ receiver 1. At the same time, a reference signal from a third oscillation circuit 18 is started to be counted 17. The ultrasonic wave 9 is reflected on a reference measuring surface 2 to be converted with the device 1 into an electrical signal and amplified and shaped 14 in the waveform delayed by a transmission time proportional to a distance 5 from the device 1 to the reference surface 2 to be compared 15 with a reference level. As the signal exceeds the reference level, the counting circuit 17 stops counting of the reference signal from the circuit 18 and the counts thereof are stored 21. Likewise, a distance (a) from the device 1 to the object being measured is measured when the object being measured exists under the device 1. Then, the distance (a) is subtracted 22 from the distance 5 and the height of the object being measured from the reference surface 2 is displayed 20.
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