Patent ID: 7259484

Claim:
A brushless motor comprising: a motor base; a rotary Shari rotatably supported by the motor base through a bearing; a back yoke in a shape of flat plate made from a magnetic material being supported by the motor base from a first surface of the back yoke in a direction perpendicular to the rotary Shari in a neighborhood of the rotary shaft; a plurality of driving coils disposed on a second surface of the back yoke opposite to the first surface confronting with the motor base; and a rotor yoke having a driving magnet in the shape of a ring integrally rotating together with the rotary Shari while confronting the driving magnet with the plurality of driving coils while maintaining a prescribed gap between them, wherein the plurality of driving coils are disposed on the back yoke around the rotary shaft within a first angular area at angular intervals of a prescribed angle, and wherein the back yoke is provided with a second angular area in which no driving coil is disposed on the second surface of the back yoke in an area within a prescribed angle around the rotary shaft, and the brushless motor further comprising a press contacting means for pressing the back yoke toward the driving magnet so as to deform the back yoke, wherein the press contacting means is provided between the motor base and the back yoke in the first angular area axially opposite to the second angular area with respect to the rotary shaft.