| 摘要 |
<p>PURPOSE:To obtain the smooth rotation of a rotor by providing a conductive shielding plate between a plurality of drive coil disposed on a printed board and the rotor. CONSTITUTION:A stator yoke 1 is mounted in a housing 8, and a printed board 3 for a drive circuit in which a plurality of drive coils 2 are annularly mounted is superposed on the yoke. A rotor 5 has an annular magnet 4, which is opposed through a slight interval to the coils 2, and its rotational shaft 6 is rotatably supported through the yoke 1 and the housing 8. In this case, a shielding plate 9 made of a thin copper plate is superposed on the coils 2 between the coils 2 and the rotor 5. The plate 9 is cut with a plurality of coaxial notches of arcuate shape formed at the shaft 6 as a center with a strip of arcuate shape. Thus, when the strips are shortcircuited at the positions of 120 deg., eddy currents generated upon rotation of the magnet 4 become in phase to be cancelled.</p> |
