Motor using rotor including interior permanent magnet, and apparatus-driving-unit employing the same motor

A motor comprising:

• (a) a stator core comprising a plurality of teeth and a yoke that links the teeth;
• (b) coils wound on the teeth;
• and
• (c) a rotor with at least one interior permanent magnet and an axis of rotation, wherein said rotor comprises:
• (c-1) a plurality of rotor cores formed from stacked rotor-core-sheets made of electromagnetic steel plates;
• (c-2) an interior permanent magnet buried within said rotor;
• (c-3) a non-magnetic-section located along the outer circumference of the rotor provided in contact with at least one longitudinal end of said permanent magnet;
• and
• (c-4) an angle “θ” made by a width of the non-magnetic section along the outer circumference of the rotor which is measured radially around the axis of rotation from a pole boundary to the distal end of the non-magnetic section,
• wherein the rotor is formed by stacking a plurality of rotor cores together, and the size of the angle “θ” is varied between adjacent rotor cores along an axial direction which is parallel to the axis of rotation.