| 摘要 |
PURPOSE:To perform fixation completely by equalizing the line speed of a fixing device in original copy mode of large size to that in original copy mode of normal size, and further making the line speed of a photosensitive drum coincident with the line speed. CONSTITUTION:In original copy mode of large size, the line speed of the fixing device 20 is equalized to the line speed in original copy mode of normal size and the line speed of the photosensitive drum 10 and the feed speed of an original are matched with the line speed of the fixing device 20. Consequently, the line speed of the photosensitive drum 10 and the feed speed of the original decrease in the original copy mode of large size. For the purpose, the discharging current of an electrostatic charging electrode 11 is lowered as compared with the copying of an original of normal size to lower the voltage of a light source for exposure, and a transfer electrode 17 and a separation electrode 10 are equal in discharging current. As for the separation electrode 8, however, a DC bias applied so as to lower the potential of the photosensitive drum 10 to zero after separation is reduced as compared with the normal-size original. Consequently, fixation becomes stable even when the large-sized original is copied. |
