| 摘要 |
PURPOSE:To promote an amplitude waveform of an encoder signal and to realize the reduction of an inner shear at a low cost by thinning or hollowing a rib of a rotor core. CONSTITUTION:Projections and recessions of rotor's pole teeth are detected by a bias magnet 6 provided to the periphery of the rotor, multiplying the rotor pole teeth by the magnetic bias, and the variation of the magnetic flux is detected by means of a magnetoelectric conversion element 5. The magnetic flux to be added to the magnetoelectric conversion element 5 is flux by the bias magnet 6 and leakage flux the rotor magnet 2. The flux by the rotor magnet 2 enters into a rotor core 1 from the end of the rotor magnet 2. The flux enters also into a rib section 4, but the rib section has a thinned part 8, magnetic resistance is sufficiently big enough, so that the leakage flux in the rotor periphery is almost uniform during the rotation, and an encoder signal with a high waveform can be obtained. |
