AUTOMATIC BALANCE CIRCUIT FOR IMPEDANCE MEASUREMENT, ADJUSTING METHOD FOR IT AND DETECTION RESISTANCE MEASURING METHOD OF THE AUTOMATIC BALANCE CIRCUIT

摘要

PROBLEM TO BE SOLVED: To easily obtain a balance state by digital control. SOLUTION: A second oscillator 106 having the same oscillation frequency is provided on the signal detection side separately from a first oscillator 101 of a signal applying side. Three different phase angles are sequentially set to the second oscillator from the CPU 109, and at each phase angle, voltage appearing the L terminal side is measured to obtain the phase angleθmin as a first establishment factor in the balance state by a specified first computing expression. The phase angle of the second oscillator 106 is fixed toθmin and then the amplitude of the second oscillator 106 is sequentially set to two different amplitudes. The voltage appearing on the L terminal side at every amplitude is measured to obtain an amplitude B min as a second establishment factor in the balance state by a specified second computing expression. The amplitude of the second oscillator 106 is B min.