| 摘要 |
<p>PURPOSE:To suppress an abrupt pulse signal at a drive coil switching drive time by interposing a shielding plate of plate shape between a drive coil and a rotor, and forming a frequency generating coil thereat. 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 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. In this case, a shielding material 9 is superposed on the drive coil 2 between the coil 2 and the rotor 5. The material 9 has a circular shielding electrode 10 on an insulating plate 9a and a zigzag frequency generating coil 11 on the outer periphery, and the electrode 10 has concentric notches 12 of arcuate shape. Thus, the coil 2 and the rotor 5 are shielded therebetween, and a frequency generation signal is output in response to the rotation of the rotor 5.</p> |
