| 摘要 |
PURPOSE:To uniformize the quantity of the beam projected onto a photosensitive body by constituting a rotary polygonal mirror and an image forming lens so that the distributions of the light beam reflectivity of the former and the light beam transmittance of the latter are opposite to each other. CONSTITUTION:A rotary polygonal mirror 3 rotated around a vertical shaft 9 is provided at a proper length ahead of an element 1 in the output direction of a light beam 2 from the element 1 so that the light beam 2 is made incident on this mirror 3 and is repeatedly deflected at about right angles. In such a case, the shaft 9 is arranged under the mirror 3 and is the rotary shaft of a driving motor 10 which rotates the mirror 3. A light beam 2' deflected by the mirror 3 is transmitted through an image forming lens group 6 and is reflected on a mirror 7 obliquely downward and passes a cylindrical lens 8 and is converged on the surface of a prescribed photosensitive drum 12. The mirror 3 is coated with such materials that its reflectivity distribution is opposite to the transmittance distribution of the light beam 2' of the lens group 6 and the lens 8. Consequently, light beam 2 and 2' are uniformly converted in the axial direction of the drum 12. |
