Patent ID: 7245051

Claim:
A three-phase brushless motor comprising: a rotation axis, a rotor yoke rotating around said rotation axis, a drive magnet formed into a ring shape and attached on said rotor yoke, said drive magnet having a plurality of magnetized poles at an equal magnetization pitch angle Pm, a plurality of drive coils disposed so that said drive coils oppose said drive magnet and the center of each said drive coil is at angular intervals of a predetermined arrangement angle Pc, the angle Pc being 4/3 times said magnetization pitch angle Pm, a rotation detecting magnet attached on said rotor yoke, and a magnetic sensor attached opposing said rotation detecting magnet so as to detect a magnetic flux of said rotation detecting magnet, wherein said magnet sensor is disposed at a position in which a magnetic flux from said drive magnet and a magnetic flux from said drive coils are canceled with each other.