Patent ID: 8604782

Claim:
An eddy current sensor comprising: an excitation coil for applying a predetermined alternating-current excitation signal to a measurement target component, wherein the excitation coil has a plurality of solenoid coils; and a detection coil for detecting a detection signal, generated by eddy current, from the measurement target component to which the alternating-current excitation signal is applied, wherein the detection coil is arranged on at least one of two sides of the excitation coil in a direction of a central axis of each solenoid coil, wherein the detection coil includes at least a first coil that is sensitive to a magnetic field in the central axis direction of each solenoid coil and a second coil that is sensitive to a magnetic field formed between the adjacent solenoid coils in a direction substantially perpendicular to the central axis of each solenoid coil, wherein the plurality of solenoid coils are arranged side by side with one another so that winding directions of the adjacent solenoid coils are opposite to each other by winding a single continuous lead wire so that upper or lower ends of the adjacent solenoid coils are alternately coupled to each other in order to generate a revolving magnetic field by the interaction between the adjacent solenoid coils.