Surveillance system having acoustic magnetomechanical marker
US4622543A · kind A · utility
39Cited by
2References
37Claims
0Family size
Inventors
Key dates
| Filing date | Mar 22, 1984 |
| Grant date | Nov 11, 1986 |
| Priority date | — |
| Expiry date | Mar 22, 2004 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B13/2442
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
An article surveillance system having an acoustic magnetomechanical marker is adapted, when armed, to resonate at a frequency provided by an incident magnetic field applied within an interrogation zone. The marker is a strip of magnetostrictive ferromagnetic material disposed adjacent to a hard magnetic element which, upon being magnetized, magnetically biases the strip and arms it to mechanically vibrate at said frequency. A substantial change in acoustic output level of the marker at the resonant frequency provides the marker with signal identity.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.