Balance correcting method for a high-speed rotatable body, a dynamic pressure bearing, and an optical scanning apparatus utilizing the dynamic pressure bearing

摘要

A balance correcting method, a dynamic pressure bearing, and an optical scanning apparatus. For balance correction a method of attaching weight to the rotatable body and another method of partly removing the rotatable body are jointly used. At the time of a first balance correcting process step, a balance correction is performed by applying adhesive agent to a recess portion formed on a circular circumference of a polygon mirror or a recess portion constructed with a rotor flange. At the time of a second balance correcting process step, the polygon mirror is partly removed or the rotor flange is partly removed. The method can be applied to a dynamic pressure bearing capable of stabilizing a rotation balance and an optical scanning apparatus having a structure capable of not changing the direction of the reflection surface of the rotatable polygon mirror. The rotating shaft is supported in the radial direction by sucking air existing between the fixing shaft and the rotating shaft. In a dynamic pressure bearing, the rotating shaft is supported in a floating state from the above-mentioned fixing shaft.