Richard E Copeland

US Patent:

60114746, Jan 4, 2000

Filed:

Apr 28, 1998

Appl. No.:

9/067333

Inventors:

Kevin R. Coffey - Fremont CA
Wing K. Ho - Boynton Beach FL
Richard L. Copeland - Boca Raton FL

Assignee:

Sensormatic Electronics Corporation - Boca Raton FL

International Classification:

G08B 1314

US Classification:

3405723

Abstract:

A single deactivation device is used to deactivate both harmonic type EAS markers and magnetomechanical type EAS markers. The deactivation device includes a housing, and a permanent magnet and a coil disposed within the housing. The coil is circular and is arranged concentrically with, and outside of, the permanent magnet. The permanent magnet forms a DC magnetic field for deactivating the harmonic type marker by magnetizing control elements thereof. The coil is driven to generate an AC magnetic field that deactivates the magnetomechanical type marker by degaussing a control element thereof. The maximum amplitude of the AC magnetic field is lower than the level of the DC magnetic field, and is substantially below the coercivity of the control elements of the harmonic type marker. The coercivity of the control element of the magnetomechanical type marker is low enough to be degaussed by the AC magnetic field.