Stepping motor and fan having the same

A fan comprising:

• a stepping motor, comprising:
• a stator comprising a coil that is wound such that a hollow space is formed;
• a rotor comprising a magnet to be disposed in the hollow space of the coil, the rotor being rotationally driven by changing magnetic poles of the stator;
• and
• a magnetic member that is disposed adjacent to the coil such that, in a stable position of the magnet, when the coil is one of excited and not excited, a direction of a winding axis of the coil crosses a direction of a polarity of the magnet;
• an impeller disposed on one side of a rotation shaft of the rotor;
• and
• a connecting device for connecting the impeller to the rotation shaft of the rotor such that the impeller is rotatable with respect to the rotation shaft of the rotor,
• wherein the connecting device allows, at the time of starting a driving of the motor, the rotation shaft of the rotor to rotate idly with respect to the impeller to thereby absorb an inertial force of the impeller and allows, as a number of rotations of the rotation shaft of the rotor increases, the impeller to rotate following the rotation shaft of the rotor, and
• wherein the connecting device comprises:
• a first connecting part connected to a side of the impeller;
• and
• a second connecting part connected to a side of the rotation shaft of the rotor;
• and
• a ball which is disposed in a space defined by the first and second connecting parts and is moveable due to a centrifugal force generated when the rotor is rotated.