Contact characteristics of a laser scanner motor in a laser printer in the low speed region

摘要

This article describes a transient contact phenomenon during start-stop operation of a polygonal mirror scanner rotor driven by a flat-type brushless DC motor and supported by a passive thrust magnetic bearing and a radial air bearing. From experimental investigations, the following characteristics have been clarified. The rotor is statically unstable in the very low speed region. This instability occurs because the stiffness of the air bearing is not induced without rotation, and it is small in the very low Speed region, whereas the magnetic negative stiffness of the magnetic bearing exists even at zero speed.