| 摘要 |
PURPOSE:To decrease the loss by the flow of air as the viscous fluid rotating and moving along the surface of a polygon mirror by constituting a casing to a circular conical or funnel shape. CONSTITUTION:The air spacing (h) between the polygon mirror 1 and the casing 5 covering the polygon mirror 1 is continuously decreased from the center of rotation of the polygon mirror toward the outside diameter part. The inner side of the casing 5 is formed to the funnel or circular conical shape. The spacing between the outside diameter part of the polygon mirror 1 and the casing 5 is, therefore, set at the value to attain the min. value of the circumferential friction and circulating friction; in addition, a sufficient space is assured in the central part of rotation of the polygon mirror 1. The loss of the disk friction is decreased in this way without impairing an assembling property. |
