| 摘要 |
PURPOSE:To eliminate futile magnetic flux of a disclike magnet, to increase a sensitivity of a signal generating magnet and to further reduce the number of manufacturing steps by integral molding by controlling orienting direction of magnetic powder in a magnet material. CONSTITUTION:Orienting direction of magnetic powder of a magnet material charged in a cavity is aligned with the direction of the line of magnetic force. That is, it is focused in the magnet to a central annular region of an operating surface side track, and the magnetic flux after magnetizing is contracted to a doughnut state. As a result, a torque generating disclike magnet 101 has almost no futile magnetic flux, and all magnetic fluxes are focused to a substantially operating surface to be effectively used, and hence a higher surface magnetic field is obtained. The magnetic flux of a signal generating ring magnet 102 of the outer periphery is effectively focused to the central region of the outer periphery, and hence its receiving sensitivity can be improved. |
