| 摘要 |
PURPOSE:To enhance the detecting accuracy in a simple structure by mounting a magnetic material disc on a rotational shaft, and providing a magnet piece and a magnetosensitive element opposed to the disc. CONSTITUTION:A pulley 3 is engaged with the shaft 2 of a motor 1. A rotary gear 5 made of a magnetic material such as an iron plate is concentrically mounted on the upper surface of a pulley 3. A detector 12 which has a Hall element 9 and a pair of disc-shaped magnet pieces 10, 11 is disposed between the upper surface of a motor case 8 and the gear 5. The element 9 generates the frequency detection output corresponding to the rotating speed of the motor 1. |
