| 摘要 |
PURPOSE:To minimize the scanning variable of an optical system and to increase a copying speed in a copying machine by comparing the value of original size on an original platen with a value obtained by dividing paper size by copying magnification and controlling the scanning variable of the optical system in accordance with the smaller value. CONSTITUTION:Reflected light from the original on the original platen arrives at a photosensitive drum 3 through an optical system scanning part 2 and forms an electrostatic latent image. A zooming unit 4 is moved in accordance with the copying magnification to expand or contract an original image. Then, the drum 3 is electrostatically charged, exposed and transferred by a process unit 5. The latent image on the drum 3 is transferred to fed paper and fixed by a fixing unit 7 and the paper is discharged to a paper discharge tray 8. In said constitution, the original size decided by the original platen 1 is compared with the value obtained by dividing the paper size decided by a paper feeding cassette 6 by the copying magnification and the scanning variable is set up to the obtained smaller value. Consequently, the scanning of the scanning part 2 can be set up to a minimum value required and the copying speed can be increased. |
