| 摘要 |
PURPOSE:To provide a constitution which prevent a polygon mirror and a noncontact bearing from coming into solid contact with each other for a polygon scanner which uses the noncontact bearing. CONSTITUTION:Spiral grooves 3'a1, 3'a2, and 3'a3 are digged in a disk 3', provided integrally with the polygon mirror 1, from the peripheral edge part to the center part to form a through passage with a mirror presser 3, and a discharge opening 3 is formed at the center-part side terminal part of the through passage. When the polygon mirror 1 rotates as shown by an arrow, air is sucked in from the outside by the spiral grooves to generate a wind moving toward the center in the grooves, and the wind is blown out from the passage 3b formed at the center part toward the rotary shaft, thereby generating a centripetal force. Even when the rotary body has slight dynamic unbalance, vibration of the rotary body is suppressed with this centripetal force to prevent the noncontact bearing from coming into solid contact with the polygon mirror. |
