Direct-current brushless motor, and polygon scanner and image forming apparatus having the same and a method thereof

Abstract

A direct-current (DC) brushless motor is provided for realizing an easy winding operation, a flat shape, effective utilization of a magnetic force, improved magnetic characteristics of a stator core, and a good rotation driving efficiency particularly at a higher rotational speed region. The DC brushless motor switches conduction to windings wound around a stator core fixedly disposed corresponding to a rotatable rotor on which a permanent magnet is fixed, to generate a rotating magnetic field which causes the rotor to rotate. The DC brushless motor includes a permanent magnet having n magnetized poles, where n is an even number, a rotatably held rotor on which the permanent magnet is fixed, a stator core having T-shaped pole shoes corresponding to the magnetic poles of the permanent magnet, windings fixed on the stator core and including a plurality of phases for selectively generating magnetic polarities in sequence, a driver circuit for switching conduction to the windings, and a rotating position detector for detecting a rotating position of the permanent magnet. The windings are divided into a plurality of winding groups for generating magnetic polarities in a plurality of the windings so as to produce a magnetic repellent force or a magnetic attractive force between all the magnetic poles of the permanent magnet and T-shaped pole shoes of the stator core associated with selected phases by the driver circuit based on a rotating position detected by the rotating position detector.