| 摘要 |
PURPOSE:To reduce the eddy current loss in a bearing support to prevent the temperature rise of a motor by providing the inner periphery side of a rotor magnet with the rotor yoke of a magnetic body member rotating integrally with the rotor magnet. CONSTITUTION:In the bearing constitution of the title apparatus, sleeve bearings 1 and 2 and a seal plate 3 are secured to an end bracket 4 and a magnetic fluid 18 is packed between the end bracket 4 and shaft 7 to the top face of the upper sleeve bearing 2. In the rotating part, on the other hand, a polygon mirror 6 is secured to the top face shaft part of a collar 5 and the shaft 7 is secured to the center. A ring-shaped rotor magnet 8 is secured to the outer periphery of the lower part of the collar 5. A rotor yoke 9 is secured to the inner periphery of the collar 5 on the inner periphery side of the rotor magnet 8. The magnetic flux (b) of the inner periphery of the rotor magnet 8 converges on the rotor yoke 9 being a magnetic body and does not cross the bearing of the end bracket 4 so that an eddy current loss is reduced. |
