Output signal processing device for eddy-current sensor

An output signal processing device for an eddy-current sensor having an exciting coil capable of forming eddy current in a conductor and a detection coil that detects the eddy current that can be formed in the conductor, the output signal processing device processing an output signal of the detection coil to be output by the eddy-current sensor,

• wherein the output signal processing device has
• an AC signal generator capable of generating a plurality of first AC generated signals having different amplitudes;
• and
• a retainer that holds reference data for identifying the first AC generated signal corresponding to the output signal that is a first reference state signal output from the detection coil in a first reference state, among the plurality of first AC generated signals,
• wherein, when a film thickness of the conductor is to be measured, the AC signal generator generates the first AC generated signal based on the reference data and outputs the first AC generated signal as a reference signal,
• wherein the output signal processing device further has
• a difference circuitry that, when a film thickness of the conductor is to be measured, receives input of the output signal that is a film thickness signal output from the detection coil and the reference signal output from the AC signal generator and acquires and outputs a film thickness amplitude that is a difference between the amplitude of the film thickness signal and the amplitude of the reference signal;
• and
• a data generator that, in the first reference state, measures an amplitude of the first reference state signal and generates the reference data,
• wherein the data generator in the first reference state measures a magnitude of an amplitude of the first reference state signal and holds amplitude data regarding the magnitude of the amplitude,
• wherein the data generator outputs amplitude designation data for designating the first AC generated signal to the AC signal generator,
• wherein the AC signal generator generates and outputs the first AC generated signal based on the amplitude designation data, and
• wherein the data generator measures a magnitude of an amplitude of the first AC generated signal output from the AC signal generator, compares the amplitude of the first AC generated signal with the amplitude data, and generates the reference data based on a result of the comparison,
• wherein the data generator, in the first reference state, measures a phase of the first reference state signal and holds phase data regarding the phase,
• the AC signal generator can generate a plurality of second AC generated signals having different phases,
• the data generator outputs phase designation data for designating the second AC generated signal to the AC signal generator,
• the AC signal generator generates and outputs the second AC generated signal based on the phase designation data, and
• the data generator measures a phase of the second AC generated signal output from the AC signal generator, compares the phase of the second AC generated signal with the phase data, and generates the reference data based on a result of the comparison.