A fuel injector, especially an injector valve for fuel injection equipment in internal combustion engines, includes a piezoelectric or magnetostrictive actuator and a valve closing body, operable by an actuator with the aid of a valve needle, which cooperates with a valve seat surface to form a sealing seat, and a valve housing. In order to reinforce a joint portion of a hub and a boss, a plate is jointed to the inside of an impeller. If the possibility of deviation is judged, the predetermined phase winding among plural phases of the stepping motor is excited again for a predetermined time period. Yet another possible feature of the handle may be a locking mechanism that resists inadvertent or accidental movement or retraction of the stent delivery system components during packaging, sterilization, shipping, storage, handling and preparation of the stent delivery system. At the initial stage, the first paper separation gear drives the second paper separation gear to rotate, and thus the paper pickup roller and the paper feed roller are respectively actuated to rotate by the second and first paper separation gears.