| 摘要 |
PURPOSE:To prevent the surface of a photoreceptor from becoming dirty and to shorten a copy time by rotating a developing roll faster in nondevelopment operation than in development operation, and reversing a supply roll slightly in nondevelopment operation then stopping it. CONSTITUTION:The developing roll 39 of the cyan developing device 5 of a color copying machine is rotated by a driving controller faster in nondevelopment operation than in development operation. Consequently, a developer 26 attracted magnetically to the surface of the developing roll 39 is removed securely in a short time with a scraper 45 by increased centrifugal force. Further, the supply rolls 32 and 37 are reversed by a specific angle in the nondevelopment operation and stopped. Consequently, the developer staying in a slanting-part A near the developing roll decreases to a level B near the supply roll 37, so it is not scooped up to the developing roll 39. Yellow and magenta developing devices 3 and 4 are the same; staining and color mixing on the photoreceptor surface are prevented and the copy time is shortened. |
