Antitheft device

Claim 1

An antitheft device comprising a tag ( 10 ) for performing a theft preventing function upon an escape from a specified control area, and an attaching member ( 2 ) for attaching the tag ( 10 ) to a commodity ( 9 ), the attaching member ( 2 ) comprising a button ( 22 ), and a pin ( 21 ) projecting from the button ( 22 ) and movable into a housing ( 1 ) of the tag ( 10 ) through a pinhole ( 12 a ) formed in the housing ( 1 ), the tag housing ( 1 ) having arranged therein a clamp member ( 3 ) for clamping the pin ( 21 ) of the attaching member ( 2 ) as moved in through the pinhole ( 12 a ), an on-off switch ( 8 ) to be depressed by the button ( 22 ) of the attaching member ( 2 ), and a theft alarm operable under the control of on-off signals from the on-off switch ( 8 ), the clamp member ( 3 ) having a clamp portion ( 34 ) for the pin ( 21 ) of the attaching member ( 2 ) to be inserted therethrough for clamping the pin ( 21 ) unremovably, the clamp member ( 3 ) being rotatably supported by a pivot provided inside the housing ( 1 ), permitting the clamp portion ( 34 ) to be disengaged from the pin ( 21 ) when rotated in one direction and being given an elastic repulsive force against the rotation, the housing ( 1 ) being provided with an inlet passage ( 14 ) for an unclamping probe ( 7 ) for pushing the clamp member ( 3 ) into rotation toward said one direction, the on-off switch ( 8 ) comprising an actuator ( 82 ) having an outer end projecting outward from the housing ( 1 ) through a hole ( 12 b ) formed in the hosuing ( 1 ), and a cylindrical guide portion ( 83 ) formed around a base end portion of the actuator ( 82 ) and providing the pivot for the clamp member ( 3 ).