Eddy currents transducer for electrical devices to control coating thickness and surface profile of metal articles

Claim 1

An eddy current transducer for electrical devices for controlling and measuring coating thickness and surface profiles of metal articles of complex configuration, comprising a ferrite core having a pair of opposed gaps therein, an induction coil wound on said core, a pair of plugs fixed to said core and respectively disposed within each of said gaps and each having a portion protruding into the space enclosed by said core, each of said plugs comprising a highly conductive nonmagnetic material, and a coating of a high conductivity material on the outer side surfaces of said core selectively applied so as to avoid formation of a shorted turn enclosing a cross section of said core and to form a closed electrical turn including the plugs along a main flux path in said core, each of said plugs being in contact only with said coating on the opposite side surface of said core, whereby a screen defining a closed electrical turn is formed, and whereby an electromagnetic stray flux interacting with the article being measured is oriented in the direction of the respective axis of said plugs.