| 摘要 |
PURPOSE: To obtain a stable time difference signal from sine wave signals having a phase difference which are generated by a Coriolis force acting on a flow tube. CONSTITUTION: Sine wave signals being proportional to a Coriolis force and having a frequency and an amplitude fixed, which are outputted from a velocity sensor fitted to a flow tube, are inputted to input terminals 1 and 1'. The sine wave input signals are converted into position signals by integrators 7 and 7' having a low-pass filter negative feedback circuit and are made trapezoidal wave signals by amplifiers 8 and 8' and outputted. The amplifiers 8 and 8' are clamped by Zener diodes ZD1 , ZD2 , ZD1 , and ZD2 making them amplifiable in active voltage regions of operational amplifiers 4 and 4', trapezoidal wave signals B and B' of a rise and a fall being always stable are obtained and compared with reference voltages set in accordance with the trapezoidal wave signals B and B', rectangular waves C and C' wherefrom a time difference signal can be taken out are determined and a time differenceΔT proportional to a mass flow rate is determined by an operational output unit 6.
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