Magnetic thrust bearing for polyon mirror scanner.

摘要

A scanning optical apparatus has a stationary shaft and a rotary sleeve rotatably fitting to each other. The apparatus is arranged to deflection-scan a light beam by rotating a rotary polygon mirror (13) attached to the rotary sleeve (23). The apparatus comprises a magnetic thrust bearing in the second permanent magnet (31), which is repulsive to a first permanent magnet (30) mounted on the stationary shaft (22), is disposed on a lower end side of the rotary sleeve (23). Further, a third permanent magnet (32) is placed on a base (21a) to which the stationary shaft (22) is fixed so that the third magnet can provide a repulsive force in a direction to urge the second permanent magnet toward the first permanent magnet.