Apparatus and method for magnetic systems
US5952734A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 10, 1997 |
| Grant date | Sep 14, 1999 |
| Priority date | — |
| Expiry date | Jun 10, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R33/389
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A coil for bucking out undesired ambient time varying magnetic fields in the region of the gap in an MRI magnet structure is energized by a servo loop controlled by a Flux Lock Circuit having, in turn, a closed loop circuit controlled by a magnetic sensor. The sensor has a pair of windings energized in parallel by a 2 KHz oscillator, the windings being oppositely poled to induce zero voltage in a third winding to which feedback signals are supplied. Extraneous fields cause an asymmetry in the current passing through the pair of windings which asymmetry is accompanied by the generation of second harmonic components which are detected and fed back to the third winding for restoring symmetry. The signal fed back to the third winding is also used for controlling the current supplied to the field bucking coil.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.