| 摘要 |
PURPOSE:To miniaturize a motor by providing a rotating frequency detecting means in the space containing the rotor and the stator of the motor. CONSTITUTION:A plurality of pairs of reflecting units 24, having different reflecting rates of light alternately, is formed on the first surface 21 of a permanent magnet 25 while a rotating frequency detecting means 31 is constituted of the reflecting units 24 and light emitting and receiving elements 30, provided on the flat plate 27 of a stator. When the stator coil 28 of a motor 20 is conducted, a rotor 26 is rotated about a motor shaft 9 or a rotating center. The light emitting and receiving elements 30 output signals in accordance with the brightness and darkness of the reflecting units 24, provided on the permanent magnet 23, when the rotor 26 is rotated. In this case, signals, whose frequency is proportional to the rotating frequency of the rotor 26, are outputted and the rotating frequency detecting means 31 detects the rotating frequency of the rotor 20. According to this method, the rotation of the motor is controlled by a control circuit (not shown in a diagram) so that the frequency of the frequency signal becomes constant. |
