CONCENTRATION SENSOR AND CONCENTRATION DETECTION APPARATUS

摘要

PROBLEM TO BE SOLVED: To cope with fluids to be measured having different viscosities while suppressing oscillation energy consumption by interelectrode capacitance and to cope with a plurality of types of concentration sensors while using a common oscillation circuit in a concentration sensor using a piezoelectric piece such as a crystal piece of which a natural frequency varies due to the adsorption of an object to be sensed. SOLUTION: An inductance is connected to the piezoelectric piece in parallel. Its inductance value is determined on the basis of the relation between an oscillation loop gain and an inductance value between an inductance value Lmax which cancels interelectrode capacitance and an inductance value Lmin evaluated as a minimum value of an inductance value capable of oscillation in a state in which the piezoelectric piece is immersed in a fluid to be measured in the natural frequency of the piezoelectric piece. COPYRIGHT: (C)2007,JPO&INPIT