BRUSHLESS MOTOR

PURPOSE:To enable to automatically start a brushless motor by treating a rotor in a magnetic field having magnetic anisotropy, and then magnetizing it under a uniform magnetic field, thereby asymmetrically forming magnetic flux density distribution in each pole with the pole as the center. CONSTITUTION:A rotor 1 is formed of an annular permanent magnet. The inner wall surface of a rotor 1 is formed in a 4-pole structure alternately magnetized at four N-poles and S-poles. Drive coils 3a-3d are respectively wound on the poles 2a-3d of the stator 2, and drive currents are supplied by a drive circuit operated by Hall elements 4 which turns ON or OFF in response to the rotating angle position of the rotor 1. One direction anisotropy is imparted in advance to the annular magnetic unit to become a rotor 1 in the manufacturing step of magnetizing the rotor 1, and to them magnetize it under uniform magnetization, thereby asymmetrically distributing the magnetic flux density to the center of each pole of the poles.