| 摘要 |
PURPOSE:To surely convert the picture element density of an optical scan by providing a first image forming optical system for bringing a luminous flux from a light source, to image formation linearly, and a rotary polygon mirror having a reflecting surface in the vicinity of the linear image forming position by this first image forming optical system. CONSTITUTION:A parallel luminous flux from a light source device 1 forms an image as a linear image being parallel to a deflecting surface in the vicinity of a reflecting surface 4 of a rotary polygon mirror 3 by a cylindrical lens 2a of the first image forming optical system 2. The luminous flux which is reflected by the rotary polygon mirror 3 is brought to image formation like a spot on a scanning surface 7 by lenses 5, 6 for constituting a second image forming optical system 50, and scans the scanning surface 7 at a uniform speed in accordance with a uniform speed rotation in the direction as indicated with an arrow of the rotary polygon mirror 3. The scanning direction by this scan is a main scanning direction. Also, the second image forming optical system 50 joins together the reflecting position of the rotary polygon mirror 3 and the scanning surface to a roughly conjugate relation with regard to the sub-scanning direction. Accordingly, even if surface inclination is generated on the reflecting surface of the rotary polygon mirror, the image forming position on the scanning surface 7 scarcely moves in the sub-scanning direction and the surface inclination is corrected. |
