US Patent 7406847 Cylinder lock

A cylinder lock capable of normal unlocking operation by an authorized key to a locking mechanism which has been illegally operated by an unauthorized key or the like, the cylinder lock comprising an engaging portion that engages a rotor in the rotational direction only when the cylinder moves toward the unlocking member is disposed to a cylinder to engage the rotor and the cylinder thereby rotating the rotor upon subsequent insertion of an authorized key to connect the rotor and the connection member thereby enabling normal unlocking operation.