Pin-clutch mechanism for theft-deterrent device

Abstract

A clutch mechanism includes a ferromagnetic anvil having an axial bore for axially receiving a pin; a cup axially aligned with the anvil for receiving a pin that is axially received by the bore of the anvil, wherein the anvil is longitudinally movable along its bore axis with respect to the cup; a spring for forcing the anvil toward a confining end of the cup; balls in the cup for engaging the pin when the anvil is forced toward the confining end of the cup, with the balls being disposed to apply radial pressure against the pin to firmly clutch the pin and thereby restrain the pin from longitudinal movement when the balls are forced toward the confining end of the cup; and a ferromagnetic shield disposed axially in relation to the anvil for diffusing magnetic flux applied axially to the anvil by a magnet external to the clutch mechanism so as to prevent less than a predetermined amount of the axially applied magnetic flux from overcoming the spring and forcing the anvil to move away from the confining end of the cup. The clutch mechanism further includes a radially disposed pole piece for directing magnetic flux applied radially by a pole piece coupled to the magnet so that at least a predetermined amount of the radially applied magnetic flux is so concentrated axially in the anvil as to overcome the force of the spring and force the anvil to move away from the first end of the cup.