| 摘要 |
PURPOSE:To remove influence of the viscosity of a fluid to be measured and radiation impedance by utilizing a signal pertaining to resonance frequency, sound velocity and gain of an amplifier composing a self-oscillator to obtain a density signal by a specified computation. CONSTITUTION:As an excitation means 61 vibrates, a wall 60 is vibrated to generate a vertical wave in a cylindrical vibrator 1. When the frequency of a drive signal applied to the means 61 is made to vary, there exists a frequency fSW which should generate a standing wave in the cylinder. A sound velocity measuring circuit 63 controls the frequency of a driving source 62 to follow the resonance point and hence, the frequency fSW at the resonance point corresponds to the sound velocity in a fluid. An arithmetic circuit 7 receives a sound velocity signal V from the circuit 63, a signal G pertaining to the gain of an amplifier from an excitation means 3 and a resonance frequency fS from a self- oscillation circuit to determine the density of the fluid to be measured cleared of influence of the viscosity of the fluid being measured and radiation impedance by performing a specified computation. |
