Magnetic detecting device and material identifying device
US7525308B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 7, 2005 |
| Grant date | Apr 28, 2009 |
| Priority date | — |
| Expiry date | May 8, 2026 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N27/72
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The present invention discloses a magnetic detecting device comprising an apply coil 1 for generating an alternate magnetic field of variable frequency and a power source 2 for the apply coil; a magnetic sensor 5 for detecting a change in the magnetic field induced by a test object 9 placed at a distance from a surface of said apply coil and toward said test object, said magnetic sensor being provided with a cancel coil 6 for canceling a magnetic field generated at the position of the magnetic sensor by a direct magnetic field and/or said apply coil; a measurement circuit 7 for the magnetic sensor for measuring a detection signal of said magnetic sensor; a lock-in amplifier circuit 8 for 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 means 10 for analyzing a phase change of the output of said magnetic sensor 5 using an output signal from said lock-in amplifier circuit 8.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.