Abstract: A brushless motor 100 is composed of a motor base 10, a rotary shaft 25 rotatably supported by the motor base 10 through bearings 22 and 23, a back yoke 20 in a shape of flat plate made from a magnetic material being supported by the motor base 10 from one surface of the back yoke in a direction perpendicular to the rotary shaft 25 in a neighborhood of the rotary shaft 25, a plurality of driving coils 31 disposed on another surface of the back yoke 20 opposite to the one surface confronting with the motor base 10 and a rotor yoke 28 having a driving magnet 24 in the shape of ring integrally rotating together with the rotary shaft 25 while confronting the driving magnet 24 with the plurality of driving coils 31 with maintaining a prescribed gap G between them, wherein the plurality of driving coils 31 are disposed on the back yoke 20 around the rotary shaft 25 at angular intervals of a prescribed angle, and wherein the back yoke 20 is provided with a not disposed angular area S in which no driving coil 31 is d

Abstract: A three-phase brushless motor in one mode of the present invention is comprised of 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 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.

Abstract: A brushless motor 100 is composed of a motor base 10, a rotary shaft 25 rotatably supported by the motor base 10 through bearings 22 and 23, a back yoke 20 in a shape of flat plate made from a magnetic material being supported by the motor base 10 from one surface of the back yoke in a direction perpendicular to the rotary shaft 25 in a neighborhood of the rotary shaft 25, a plurality of driving coils 31 disposed on another surface of the back yoke 20 opposite to the one surface confronting with the motor base 10 and a rotor yoke 28 having a driving magnet 24 in the shape of ring integrally rotating together with the rotary shaft 25 while confronting the driving magnet 24 with the plurality of driving coils 31 with maintaining a prescribed gap G between them, wherein the plurality of driving coils 31 are disposed on the back yoke 20 around the rotary shaft 25 at angular intervals of a prescribed angle, and wherein the back yoke 20 is provided with a not disposed angular area S in which no driving coil 31 is d

Abstract: A three-phase brushless motor in one mode of the present invention is comprised of 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 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.