Patent ID: 6693425
Filing Date: 2004-02-17
Classification: G01N

Abstract:
A sensor for detecting defects in a component, said sensor comprising:an electric coil fed with a varying electrical current to create a varying magnetic field penetrating at least partly into said component under test; and a defect detector means comprising a giant magnetoresistor, wherein: said components are accommodated in a protective housing having a detection face adapted to be disposed near and parallel to a surface of said component under test; said coil has its axis A perpendicular to said detection face; said magnetoresistor is situated in the vicinity of said detection face and is disposed so that its sensitivity axis Al sensitive to variations in a magnetic field is parallel to said detection face of said housing, and said sensor further comprises a first permanent magnet disposed so that it magnetically biases said giant magnetoresistor in the direction of its sensitive axis Al to a value such that the operating point is a point on a curve, representing the output signal of said giant magnetoresistor as a function of the value of the component of said magnetic field in the direction of said sensitive axis, which is situated in the vicinity of the middle of a substantially rectilinear portion of said curve.