| 摘要 |
PROBLEM TO BE SOLVED: To further reduce contamination due to that flows in an optical box. SOLUTION: An air flow is generated around a rotating polygon mirror 292 by the rotation of the rotating polygon mirror 292 in the direction shown by an arrow K. The flow speed of the air flow reaches a maximum, when the air passes through a narrow gap between the rotating polygon mirror 292 and the rear end part of an optical box 200. A negative pressure part T is generated according to the Bernoulli's law at the rear end part of the optical box 200 where the flow speed is high. The negative pressure part T is not always constant, but its size will vary with a certain period, as shown by dotted lines F1 and F2. Due to this variation, the air inflows and outflows between the inside of the optical box 200 and the inside of an pressure regulation chamber 208 via adjustment holes 300Y, 300M, 300C and 300K. Furthermore, external air inflows and outflows through the open part 210 of the pressure regulation chamber 208 according to the inflow and outflow of the air D1. Thus, the inflow and the outflow of the external air, containing dust will stay in the pressure regulation chamber 208 and will not be sucked into the optical box 200. COPYRIGHT: (C)2007,JPO&INPIT |
