| 摘要 |
PURPOSE:To prevent the thermal deformation of a correction lens and to well maintain optical characteristics by integrally forming a heat radiating duct to at least either of the front and rear surfaces of the correction lens in approximately parallel with a main scanning direction. CONSTITUTION:A laser beam source 4 is disposed to face the reflection surface 3 of a polygon mirror 2. The surface to be scanned of a photosensitive drum, etc., is disposed via the correction lens 5 on the main scanning optical path of the light which is emitted from the laser beam source 4 and is deflected to scan by the reflection surface 3 of the polygon mirror 2. The heat radiating duct 6 is integrally formed on the front surface of the correction lens 5 in parallel with the main scanning optical path. A blast pipe 10 of a suction fan 9 which is a cooling mechanism is connected via a freely deformable communicating pipe 8 made of rubber to the suction port opened at one end of the heat radiating duct 6. Further, the inside base of the heat radiating duct 6 is integrally and projectingly provided with many heat radiating fins 15. The surface areas of these heat radiating fins 15 are increased according to the flow direction of the air by the projecting provision heights thereof varying successively in the main scanning direction. |
