Patent ID: 7969312

Claim:
A device for magnetic material detection coupled to an Electronic Article Surveillance (EAS) electromagnetic system, the system being comprised of: at least one antenna/sensor ( 6 ) for detecting EAS tags different from the magnetic material and generating a differential signal responsive to an EAS tag; and a control unit ( 7 ); characterized in that the device comprises: an “n” order filter ( 1 ) wherein n is an integer, a buffer or a high impedance insulator circuit ( 2 ), a sensitivity adjuster or gain control circuit ( 3 ), a control logic ( 4 ), and an alarm module ( 5 ), wherein the filter ( 1 ), the buffer ( 2 ), the sensitivity adjuster or gain control circuit ( 3 ), the control logic ( 4 ) and the alarm module ( 5 ) are compatibly internally or externally coupled to the EAS electromagnetic system; the control unit ( 7 ) receives a differential signal detected from the antenna/sensor ( 6 ) representative of the EAS tag and the magnetic material, and internally or externally forwards it to the “n” order filter ( 1 ); the output of the “n” order filter ( 1 ) is a signal presenting both AC and DC component information, this signal is sent to the buffer or high impedance insulator circuit ( 2 ), which buffers the previous stages to avoid harm in the EAS tag detection and filters out the DC component, which DC component is then processed by the sensitivity adjuster or gain control circuit ( 3 ) and given to the control logic ( 4 ) for digital filtering; and the control logic ( 4 ) output from the digital filtering is connected to the alarm module ( 5 ) for generating an alarm when said magnetic material is detected.