| 摘要 |
PURPOSE:To enable output signals which are strong to noise, are highly accurate and stable to be obtained by digitally constituting time measuring circuits from transmission up to reception of ultrasonic waves. CONSTITUTION:The gauge is constituted by an ultrasonic wave transmission circuit A and its reception circuit B, a reference signal generating circuit C provided with a temperature compensating circuit, an arithmetic circuit D which counts the pulses transmitted from the circuit C within the time when the signals which the ultrasonic waves transmitted from the circuit A fall against the surface under measurement and reflected therefrom are received in the circuit B and a circuit E which converts the operated values as level valves and outputs the same. In addition, a counter 22 which renews counting at each incoming of the reflection signal to the circuit D, an up-down counter 27 for the level output under measurement which counts a fixed pulse at each incoming of the signal and a magnitude comparator 26 which compares the magnitudes of the counters 22 and 27 and gives an increase or decrease instruction to the counter 27 are provided to perform digital processing and make the output signals stable. |
