| 摘要 |
PURPOSE:To prevent a picture from becoming thin in a system by which a nonexposure part is image-developed, by varying size of an image forming spot diameter on a recording medium of an optical beam in accordance with size of an area to be image-developed. CONSTITUTION:An optical beam from a laser array 10 is deflected and scanned by an optical deflector 12 through a collimator lens 11, and its image is formed on a photosensitive drum 1 through an image forming lens 13. The laser array 10 is inclined against the optical axis of the collimator lens 11A and is installed so that a light source 10A comes to a focal position of the collimator lens 11, thererfore, a light source 10B is slightly shifted from a focal position of the collimator lens 11B, and image forming spots 15A, 15B on the photosensitive drum 1 show intensity distributions 16A, 16B, respectively. The diameter of the image forming spot becomes smaller (D1) in case when only the light source 10A has been lighted than the case when both the light sources 10A, 10B have been lighted, and the thin lines being in parallel with the main scanning direction can be made somewhat thick by inhibiting that the light source 10B is lighted. |
