A Novel EC Probe with Independent Excitation and Pick-up Coils

摘要

To overcome the low sensibility of the most basic EC probe with a single coil in the metal barcode label application, we present a novel eddy current probe with independent excitation and pick-up coils in this paper. The impedance change of the probe is deduced by using the circuit theory. Through the phase detection, the lift-off problem has been obviously reduced and the positions of notches and spaces in a metal barcode label can be indicated precisely. Experiments demonstrate the high sensibility of the two-coil probe.