Pulsed magnetic release mechanism

Abstract

An electromagnetic release apparatus and method are provided for unfastening a magnetically actuated surveillance marker clip assembly from an article. The release apparatus includes a primary solenoid coil that, when energized, produces a magnetic field of sufficient force to initially unlock the clip assembly for removal. A secondary magnet produces another magnetic field sufficient in force to retain the clip assembly in the unlocked position. The secondary magnet is mounted to a piston slidably received in the central bore of the primary solenoid coil. The primary solenoid coil is energized by inserting the clip assembly into the central bore of the coil, thereby, pressing the piston downwardly until it closes a 'one-shot' microswitch. The electrical charge of a capacitor is then discharged through the primary coil to produce the relatively high power magnetic field for unlocking the clip assembly. A clip assembly removal reminder system assures proper processing of an article and removal of the clip assembly by the clerk or cashier. The system includes an interrogation and detection circuit for detecting the presence of a clip assembly at a final checkout station. An alarm remains continuously activated until the clip assembly is removed from the final checkout station and the release apparatus is activated to remove the clip assembly from the article.