Electronic article surveillance tag with tamper resistant magnetic lock

摘要

Method for operating a magnetically controlled lock in an EAS tag (100) involves the application of a magnetic field to a plunger (322) within a housing (102) of the EAS tag. The applied magnetic field is used to cause a translational movement of the plunger in a first direction. The method can further involve causing a latch (320) to pivot about a pivot axis (807) by using the translational motion (1002) of the plunger to apply a torque (1004) to the latch. Rotation of the latch in this way causes it to move to an unlocked position which releases a locking pin (106).

主权项

1. A magnetic lock that is resistant to defeat caused by forceful impacts, comprising:
a housing formed of a rigid material; a shackle having a first end slidable within a first channel defined in the housing and a second end which is removable from a second channel defined in the housing which is offset from the first channel; a locking pin disposed within the housing so as to secure the shackle to the housing; a pin channel defined within the housing, the pin channel arranged to removably receive therein the locking pin along a channel axis so that the magnetic lock is coupleable to and decoupleable from an item at least partially by using the locking pin and shackle, where the item is to be protected by the magnetic lock; a latch assembly disposed within the housing, the latch assembly including
a latch disposed adjacent to the pin channel, the latch pivotally mounted within the housing, the latch configured to lockingly engage the locking pin when in a first pivot position in which the magnetic lock is securely coupled to the item, and to release the locking pin in a second pivot position in which the magnetic lock is decoupleable from the item,a plunger formed of a material responsive to an applied magnetic field, the plunger including an engagement face,a plunger guide channel formed in the housing, the plunger guide channel arranged to facilitate translational movement of the plunger along a guide channel axis from a first position to a second position when the plunger is exposed to the applied magnetic field, anda resilient member arranged to resiliently urge the engagement face of the plunger into contact with a base of the latch; wherein a first torque is applied to the latch responsive to the translational movement of the plunger from the first position to the second position so as to cause the latch to rotate from a first pivot position in which the latch engages the locking pin to a second pivot position in which the latch is disengaged from the locking pin.