The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 28, 2009
Filed:
Jul. 07, 2005
Keiji Tsukada, Okayama, JP;
Toshihiko Kiwa, Okayama, JP;
Keiji Tsukada, Okayama, JP;
Toshihiko Kiwa, Okayama, JP;
Okayama University, Okayama, JP;
Abstract
The present invention discloses a magnetic detecting device comprising an apply coilfor generating an alternate magnetic field of variable frequency and a power sourcefor the apply coil; a magnetic sensorfor detecting a change in the magnetic field induced by a test objectplaced at a distance from a surface of said apply coil and toward said test object, said magnetic sensor being provided with a cancel coilfor canceling a magnetic field generated at the position of the magnetic sensor by a direct magnetic field and/or said apply coil; a measurement circuitfor the magnetic sensor for measuring a detection signal of said magnetic sensor; a lock-in amplifier circuitfor detecting an output of said measurement circuit for the magnetic sensor into two signals having the same frequency as that of said apply coil and phases different from each other by 90 degrees; and an analysis meansfor analyzing a phase change of the output of said magnetic sensorusing an output signal from said lock-in amplifier circuit