| 摘要 |
PURPOSE:To prevent an irregularity in rotation of an image carrier from affecting an image by setting the length of the image carrier from an exposure position to a development position arranged on the downstream side of the image carrier in its moving direction to a half as long as the peripheral length of the image carrier, and operating the moving means for a developing device when an exposing means is not in operation. CONSTITUTION:The outer peripheral length L of the drum type image carrier 1 which has an electrophotographic sensitive layer on its surface is L1+a or long when maximum recording length is denoted as L1. An electrostatic charger 2, an exposing device 3, developing devices 4-7 which contain developers, a transfer device 10, etc., are arranged nearby the outer periphery of the image carrier 1 in the rotating direction. The exposing device 3 and developing devices 4-7 are so arranged that the length L2 on the image carrier from the exposure position (b) of the exposing device 3 to the development position (c) of the developing device 7 is shorter than the half of the overall peripheral length by >=(a); when the exposing device 3 is not in operation, the developing devices 4-7 are moved toward the carrier 1 by a cam 8 fixed on a rotary shaft 17. Consequently, the fine gap between the developing means and image carrier is held stably and the irregularity in the rotation of the image carrier when a developing device moves is prevented from affecting the image.
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