| 摘要 |
PURPOSE:To provide a motor which has a small size, a high efficiency, a low torque ripple and a low cost by opposing the pole faces of a plurality of concentric rotor magnets to both front and rear surfaces of a stator coil formed by plastic molding an air core coil. CONSTITUTION:An air core coil is plastic-molded to form an air core stator coil 21. Two rotor magnets 18, 18' are so disposed at both up and down sides of the coil 21 that the pole faces of different polarities are opposed to each other. Rotor yokes 19, 19' are secured to a stationary piece 4, and a speed signal frequency signal generator made of an FG magnet 100 and an FG substrate 95 is provided between the rear surface of the yoke 19 and the lower surface of a lower drum 3. A lower drum 3 contains a rotary side yoke 15 and a stationary side yoke 14. An upper drum 4 secures a magnetic head 8 thereon. |
