Abstract
Laser printers, which feature quiet, fast, high-quality printing, are evolving towards digital copiers with even faster and higher quality printing performance. This trend requires faster and more precise rotation of the polygon mirror motor of the laser beam scanning mechanism. Thus, bearings are becoming a key technology for the advancement of laser printers. This report proposes an integrated bearing unit that employs ferro-fluid for the bearing lubrication and seals in a new concept of leakage-free high-speed bearings. The intention is to take advantage of hydrodynamic oil-film bearings with high stiffness and damping characteristics to solve the oil leakage problem, and use them in place of ball-bearings or air bearings to get highly precise rotation. Leakage is completely prevented by using a compound seal of a ferro-magnetic seal and a viscous seal. The structural features of these bearings and experimental results concerning their lubrication and sealing performance and rotation accuracy when applied to a polygon mirror motor operating from 10000 to 30000 r/min are presented. The ferro-fluid bearings provide satisfactory friction torque and stiffness characteristics and the proposed bearing unit can be utilized with the polygon mirror motor.
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