Ferromagnetic object detector with comparison of signal maximums from a pair of detection coils
US5001425A · kind A · utility
26Cited by
13References
28Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Dec 13, 1989 |
| Grant date | Mar 19, 1991 |
| Priority date | — |
| Expiry date | Dec 13, 2009 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB65F2210/1525
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A device for detecting the passage of a ferromagnetic object through a predetermined space has a substantially circular base which circumscribes the space. An inner detector coil and an outer detector coil are concentrically mounted in coplanarity on the base. Voltages are induced on the coils in response to the passage of a nearby magnetic field, such as the small permanent magnetic field associated with a ferromagnetic object. A signal processing circuit compares the induced voltages on the coils to indicate passage of a metal object through the circumscribed space when the inner coil voltage exceeds the outer coil voltage.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.