Minute magnetic body detecting sensor and foreign substance detecting device

A foreign substance detecting device comprising:

• a magnetic detecting element for outputting a damped oscillating voltage in response to a local magnetic field generated by a magnetized minute magnetic body such as size 0.1 mm or 0.3 mm, positioned at a state of unspecific position and orientation on which a detection sensitivity is depended around a magneto-sensitive body of an amorphous material to which an electrical pulse current or an alternate current is applied,
• a signal processing device for processing the damped oscillating voltage to output an output signal, and
• a display device for displaying on a display portion based on the output signal of said signal processing device, wherein
• said magnetic detecting element comprises at least two magneto-sensitive bodies which are disposed on a plane such that sensitive axes of maximum sensitivity directions thereof are mutually different directions and such that one of said at least two magneto-sensitive bodies is not able to detect the magnetized minute magnetic body and cannot output an output signal of a significant magnitude and another magneto-sensitive body is able to detect the magnetized minute magnetic body and output the output signal of the significant magnitude, and
• a plurality of said magnetic detecting elements are disposed with distances in a detection region in the same plane, and wherein
• said foreign substance detecting device is configured such that said signal processing device obtains an amplitude of the local magnetic field generated by the magnetized minute magnetic body by processing based on the damped oscillating voltage in response to the local magnetic field of the magnetized minute magnetic body detected by said magnetic detecting element in case of a foreign substance of the magnetized minute magnetic body entering in an inspected object placed on said detection region, and said display device displays the foreign substance of the magnetized minute magnetic body entering in the inspected object placed on said detection region on said display portion.