| 摘要 |
PURPOSE:To form a proper image which has high contrast and no fog by varying and controlling both the amount of exposure to an original and the developing bias of a developing device, and using an area where optential variation among photosensitive characteristics of a photosensitive body is large. CONSTITUTION:A part of light information 3 from the original 8 is branched by a branching device 11, and a light information detector 12 detects the state of the background parts of the original 8 to control a lighting device 9 and a developing device 4 by an arithmetic device 13 and controllers 14 and 15. The exposure to the original 8 is controlled so as to utilize the range where variation in the surface potential of a photosensitive body is larger than the unit amount of the exposure of the photosensitive body 1, and the developing bias of the developing device 4 is controlled so that the part of the obtained photosensitive body potential corresponding to the background part is not developed. Thus, the characteristics of the photosensitive body 1 are utilized effectively to obtain the image which has high contrast and no fog. |
