Patent ID: 11946740
Assignee: ELCOMETER LIMITED
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 16:
17. A coating thickness measuring instrument comprising:
a magnetic induction probe comprising at least one drive coil and at least one pick-up coil;
a driver for driving an alternating drive current in the or each drive coil;
a detector for detecting an output of the or each pick-up coil; and
a processor configured to: apply a transfer function to a detector output to produce an instrument output corresponding to a measured coating thickness;
and scale both the alternating drive current and the detector output simultaneously in response to the instrument output,
wherein the transfer function is, T
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where T(x) is the transfer function with output Vout(x)=T(x)Vin, Vd(x) is the detected output of the or each pick-up coil, G1 and G2 are first and second scaling factors which define the scaling applied to the alternating drive current and detector output respectively, and Vin, f3 and Voseare constants, Vin is a voltage set point used to control the alternating drive current, Vose is an amplitude of the alternating drive current and Vout(x) is the instrument output used to determine the measured coating thickness.