Patent ID: 8776614

Claim:
A Coriolis mass flowmeter comprising: two sensors configured to measure deformation amounts of a measurement tube which generates when the measurement tube which is fixed at both ends is vibrated as a fluid flows through it; a first ΔΣ modulator and a second ΔΣ modulator configured to convert output signals of the two sensors into pulse density signals, respectively; a first LPF and a second LPF configured to convert the pulse density signals that are output from the first ΔΣ modulator and the second ΔΣ modulator into multi-bit signals, respectively; a signal computing module configured to calculate a mass flow rate on the basis of the two multi-bit signals; a resonance circuit configured to generate an excitation signal on the basis of at least one of the output signals of the two sensors; a drive output module configured to amplify the excitation signal; and an exciter configured to excite the measurement tube using an amplified excitation signal, wherein the resonance circuit comprises: a multiplier configured to amplify one of the pulse density signals that are output from the first ΔΣ modulator and the second ΔΣ modulator or a signal generated from the pulse density signals that are output from the first ΔΣ modulator and the second ΔΣ modulator to generate a multi-bit signal; an amplification factor controller configured to control an amplification factor of the multiplier on the basis of at least one of the multi-bit signals that are output from the first LPF and the second LPF so that vibration amplitude of the measurement tube is stabilized; a third ΔΣ modulator configured to convert an amplified, multi-bit signal into a pulse density signal; and a DAC configured to generate the excitation signal on the basis of the pulse density signal that is output from the third ΔΣ modulator.