Being the measuring method which detects mass from change of oscillation frequency of the driving circuit of mass

摘要

Try to be able to do the measurement of mass securely. Mass measurement equipment 10 has the driving circuit 14 which you force drive piezoelectric vibrating reed 12. The driving circuit 14 has the PLL circuit 20. As for the PLL circuit 20, the variable voltage control oscillating circuit 24 outputs the driving signal. The driving signal, through distributer 22, in piezoelectric vibrating reed is given 12 and phase comparator 26. Phase comparator 26 outputs the signal which responds to the phase difference of the output signal and the driving signal of piezoelectric vibrating reed 12. This signal, passing loop filter 28, flows directly straight to voltage, is given to voltaged controlled oscillator 24 as control voltage. As for voltaged controlled oscillator 24, oscillation frequency changes according to control voltage, outputs the output signal of piezoelectric oscillator, 12 and the driving signal which does not cause phase difference resonates piezoelectric vibrating reed 12. Signal processing unit 16, calculation doing the output frequency of voltaged controlled oscillator 24, calculates the resonance frequency of piezoelectric vibrating reed 12.