| 摘要 |
PURPOSE:To expose a picture in a slit shape where a desired illuminance distribution can be obtained even in an unmagnified mode and a variable power mode by providing plural light sources and controlling each lighting state independently. CONSTITUTION:When an original 2 in A3 size, for instance, is enlarged twice on a transfer paper 16 in A1 size and copied in the variable power mode, it is unnecessary that external light sources L1-L3 and L14-L16 light up, because the original 2 is in A3 size and halves the A1 size. Said procedure is made by modifying the positions of the 2nd mirrors, etc. At this time, since a slit 26 at the side of the original 2 is fixed, the slit width on the surface of a photosensitive drum 11 changes in proportion to a magnification, and the illuminance distribution also changes. Accordingly, the duty cycle ratio of a pulse is controlled, whereby the slit shape on the photosensitive drum 11 is considered a fixed thing and picture quality is improved. |
