Patent ID: 6041642
Filing Date: 2000-03-28
Classification: G01G,G01H,G01N

Abstract:
A method for measuring a natural resonant frequency of movement of a spring element, the method comprising:causing vibratory movement of the spring element;applying an electrical input signal of adjustable frequency and variable phase from a voltage controlled oscillator to a transducer coupled to the spring element;converting movement of the spring element to an electrical output signal;detecting a phase difference between the electrical input signal and the electrical output signal, wherein said phase difference represents an oscillation frequency of the spring element due to accumulation of chemical substances on a surface thereof;integrating the phase difference to provide an input to the voltage controlled oscillator; andwherein the voltage controlled oscillator adjusts the frequency of the electrical input signal until the phase difference which is obtained corresponds to the natural resonant frequency of vibratory movement of the spring element.