| 摘要 |
<P>PROBLEM TO BE SOLVED: To suppress noise and temperature rise, resulting from the high-speed rotation of a polygon motor and a polygon mirror. <P>SOLUTION: An outer casing 66 comprises a bottom portion 63, an outer surrounding wall 64 standing at the outer periphery of the bottom portion 63, and an outer cover 51, whereas an inner casing 67 comprises a part of the bottom portion 63, an inner surrounding wall 65, and an inner cover 52. Thus, the inner casing 67 covers the polygon motor 53 and the polygon mirror 54, and the outer casing 66 covers the inner casing 67 from the outside. Thus, noise resulting from the high-speed rotation is suppressed. A circular air vent 70, smaller than the inscribed circle of the polygon mirror 54, is formed in the inner cover 52 and directly above the polygon mirror 54, and the air heated up in the inner casing 67 is discharged between the inner casing 67 and outer casing 66 via the air vent 70. <P>COPYRIGHT: (C)2008,JPO&INPIT |
