Patent ID: 7638907

Claim:
A step motor mounted inside a camera and adapted to move a driven member of said camera, the step motor comprising: a yoke iron, said yoke iron comprising a base, two arms respectively extended from said base at two sides and terminating in a respective free end, and four magnetic poles respectively formed on the free ends of said arms and each junction between said base and said arms, said base of the yoke iron having a recessed portion formed at a side of the base thereof facing said two magnetic poles of the free ends of said arms for separating said two magnetic poles on the junctions between said base and said arms; two windings respectively surrounding said two arms of the yoke iron; a magnet rotatably floating among said magnetic poles of the yoke iron by a magnetic force, said magnet comprising a cylindrical iron core divided into a plurality of sectors abutted against one another, said sectors having two different magnetic poles alternatively arranged together; and a crank coupled to and rotatable with said magnet, said crank having an actuating axle connected to said driven member of the camera for moving said driven member of the camera upon rotation of said magnet.