BEARING PART FOR OPTICAL DEFLECTOR AND DYNAMIC PRESSURE AIR BEARING TYPE OPTICAL DEFLECTOR

摘要

PROBLEM TO BE SOLVED: To maintain the bearing rigidity while reducing the windage loss at the time of the rotation of a rotary polygon mirror or rotary single-surface mirror by lowering the pressure in the optical deflector constituted by putting a motor rotation part, which is freely rotatable around the outer periphery of a dynamic pressure shaft together with the rotary polygon mirror or rotary single-surface mirror, hermetically in a case and a cover member. SOLUTION: A center hole which communicates with the outside air is bored along the length of the center part of a dynamic pressure shaft 1 having a feed herringbone groove (q) (or (r)) bored on one side of a dynamic pressure bearing M and a hole (b) is provided in the center of the herringbone groove (d) of the dynamic pressure bearing M and the feed herringbone groove (q), or a hole (c) is formed in the center of the herringbone groove (e) of the dynamic pressure bearing M and the feed herringbone groove (r).