Patent ID: 6465918
Filing Date: 2002-10-15
Classification: G02B,H02K

Abstract:
An image forming apparatus, comprising:a rotatably held photosensitive image carrier; a charging device configured to uniformly charge a surface of said image carrier; an exposing device configured to irradiate a laser beam onto the surface of said image carrier charged by said charging device to form a latent image on the surface, said exposing device including a polygon scanner having a direct-current brushless motor; and developing device configured to develop the latent image formed by the exposing device, wherein the direct-current brushless motor, includes: a permanent magnet having n magnetized poles, where n is an even number; a rotor on which said permanent magnet is fixed, said rotor being rotatably held; a stator core having T-shaped pole shoes corresponding to the magnetized poles of said permanent magnet; windings fixed on said stator core and comprising a plurality of phases configured to selectively generate magnetic polarities in sequence; a driver circuit configured to switch conduction to said windings; a rotating position detecting mechanism configured to detect a rotating position of said permanent magnet; and said windings being divided into a plurality of winding groups configured to generate magnetic polarities in a plurality of said windings so as to produce a magnetic repellent force or a magnetic attractive force between all of the magnetized poles of said permanent magnet and T-shaped pole shoes of said stator core associated with selected phases by said driver circuit based on a rotating position detected by said rotating position detecting mechanism, wherein said plurality of winding groups include said number n of windings per phase, and are disposed on a circumference at equal intervals, said winding groups corresponding to said phases being connected in a Y-shaped connection configuration, wherein adjacent windings in each of said phases are wound such that opposite polarities occur in alternation when a current flows therethrough, wherein a current flowing into said winding groups from a common connection point of said Y-shaped connection configuration causes opposite polarities to occur in adjacent windings, and wherein the driver circuit selectively conducts windings in two of the three phases of the winding groups and the current flows to the selected two phases in series through the common connection point of the Y-shaped connection configuration to generate a magnetic repellent force and a magnetic attractive force between the entire periphery of the permanent magnet and the stator core forcing the rotor to rotate.