| 摘要 |
A closed type polygon scanner has a housing, a rotor which is rotatively supported to a rotating shaft fixed to the housing and which includes a polygon mirror, a motor which generates a magnetic force to the rotor and rotates the rotor, and a cover. The cover includes an outer peripheral portion fixed to an outer peripheral portion of the housing, and covers the rotor together with the housing. An opening is formed at a predetermined portion in the cover facing a mirror surface of the polygon mirror through which a laser beam passes, and a window member is fixed to the opening in closed state. An inner peripheral surface of the cover facing the mirror surface of the polygon mirror is formed cylindrically and almost coaxially to a rotating axis of the rotating shaft, and a width in the rotating axis direction of the opening is set to a predetermined width relative to a width of the polygon mirror so that turbulent air generated around the polygon mirror is reduced. |
