| 摘要 |
PURPOSE:To obtain a favorable speed detecting signal of the transistor motor as not affecting to magnetic field flux by a method wherein protruding and recess parts are formed on the outer circumferential part of a rotor consisting of a conductive material, speed detecting electrodes are made to face to the protruding and recess parts thereof and the rotating speed is detected from a change of electrostatic capacity. CONSTITUTION:At the rotor 2 being equipped with a ring type field magnet 5 on one-sided face of a flywheel 4 consisting of the conductive material, the protruding and recess parts 41 are formed on the outer circumferential face of the flywheel 4. Moreover the speed detecting electrodes 14, 15 being provided with protruding and recess parts 141, 151 are equipped as to face to a part of those protruding and recess parts 41 to a stator plate 1 through spacers 14, 15 respectively. A voltage is applied as to form a closed circuit through the rotor 2, the speed detecting electrodes 14, 15 and the stator plate 1, and the rotating speed of the rotor 1 is detected by the change of electrostatic capacity between the rotor 2 and the electrodes 14, 15 to be caused by the rotation of the rotor 2. |
