| 摘要 |
PURPOSE:To obtain an image with excellent balance by setting up the electrostatically charged capacity/mass of each developer in each developing device in proportional to the difference between the surface potential of an image carrier and the potential of a developing bias in each developing position at the time of forming an image of the image carrier. CONSTITUTION:A photoconductive layer of a photosensitive body to be an image carrier is constituted of a layer especially including epsilon-type copper phthalocyanine or gamma-type non-metallic phthalocyanine and developing devices 5-8 are arranged with prescribed intervals on the downstream side of the photoconductive layer so as to be opposed to the layer. When it is defined that the charged capacity of the developer in each developing device is Q (unit C) and its mass is M (unit g), the difference between the surface potential of each developing position and the developing bias voltage is made almost proportional and absolute values (Q/M)5>(Q/M)6>(Q/M)7>(Q/M)8 is defined. Even if dark attenuation is increased and a potential difference is reduced in accordance with a distance from a charging position, the Q/M is reduced in accordance with said changes so that toner adhesion can be sufficiently held.
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