| 摘要 |
PURPOSE:To simplify a structure and reduce a cost and eliminate uneven torque and perform a smooth rotation, by adopting a starting system without depending on cogging torque. CONSTITUTION:A rotary yoke 12 is fixed on a rotary shaft 9, and on the lower surface of the yoke, a rotary magnet 13 is fixed. On a printed board 14 facing the rotary magnet 13 via an air gap, four armature coils LA, LA', La, Lb' and a position-detecting electromagnetic-conversion element 15 are arranged. The poles N of the driving poles 17 of the rotary magnet 13 are arranged at the electrical angle of 240 deg. (the mechanical angle of 120 deg.), and the poles S are ar ranged at the electrical angle of 120 deg. (the mechanical angle of 60 deg.), and the poles N, S are alternately arranged. On the outer peripheral section of the poles, four position-detecting poles 18 are formed. By detecting the rotation of the rotary magnet 13 and exciting the coils LA, LA' and LB, LB' alternately by every 180 deg. at the electrical angle, uniform torque is obtained, and members for generating cogging torque for start are not required. |
