| 摘要 |
PURPOSE:To suppress generation of noise by arranging two or more permanent magnets with their polarities alternately reversed in the periphery of a rotary shaft and applying sinusoidal drive voltage to a drive coil. CONSTITUTION:A rotor 4 is constituted of fans 41 with a blade radially formed, disk-shaped iron-made rotor yoke 42 and four permanent magnets 40. Each permanent magnet 40 is arranged in a manner wherein the polarity is alternately reversed such as N, S, N, S. Only a single drive coil 8 is provided so as to be opposed to the permanent magnets 40. A Hall IC9 is provided adjacent to the rotor 4 in a position at a 135 deg. angle formed to the drive coil 8. The rotor 4 is rotated by controlling drive voltage applied to the drive coil 8 from a driving circuit in accordance with a rotational position of the permanent magnet 40 by an output signal from the Hall IC9. |
