| 摘要 |
PURPOSE:To obtain stable picture quality by eliminating an image density difference of halftones during variable magnification to equal magnification, etc., by holding the time when a photoreceptor moves from a pre-exposure position to a secondary simultaneous charging and exposure position constant without reference to its moving speed. CONSTITUTION:A lamp 8 is arranged behind a primary charger 4 and during variable magnification (contraction in this case), the lamp is turned on. Then, a pre-exposure position A is extended to a position A' and the distance from the pre-exposure position to a secondary simultaneous charging and exposure position B is shortened, so that the moving time of a photoreceptor 1 during nonmagnification is nearly equal to that during magnification variation. Therefore, the VM and VN of an E-V characteristic curve become nearly equal to each other and an image density difference of halftones is eliminated, thereby obtaining stable picture quality. |
