| 摘要 |
PURPOSE:To precisely control the speed of a sewing machine with high resolution by facing a stator and a rotor having many teeth, forming a closed magnetic circuit of the stator, the rotor and a permanent magnet, and producing a pulse train proportional to the rotating speed from the coil crossing the magnetic flux. CONSTITUTION:A rotating shaft 1 is mounted on a sewing machine pulley, and a rotor 6 made of magnetic material is secured onto the shaft 1. Many teeth are formed on the periphery of the rotor 6, and are faced via a gap with a stator 5 made of magnetic material having teeth of the number equal to or of integer number times of the teeth of the rotor. A closed magnetic circuit is formed of the stator 5, the rotor 6 and a ring-shaped permanent magnet 9, and a signal of the frequency proportional to the rotating speed can be obtained from the coil 10 provided to cross the magnetic flux of the magnetic circuit. This signal is amplified, shaped in waveform, and is obtained as a pulse train proportional to the rotatng speed of the sewing machine. |
