| 摘要 |
PROBLEM TO BE SOLVED: To provide a developing device for preventing developer from being scattered even in the case of increasing the number of rotations of a developing sleeve and a magnetic roller. SOLUTION: When a belt photoreceptor 1 starts to be driven at the start of copying, an image is read and two-color conversion processing is performed, and a 1st color developing device and a 2nd color developing device start to be driven, and first of all, the 1st color image is developed. Then, the 1st color developing device starts to be driven, simultaneously, a magnet roller 9-2 and a developing sleeve 9-1 for the 2nd color developing device are rotated at a prescribed rotating speed. Besides, after a prescribed time passes, the magnet roller 9-2 is elevated up to a prescribed position shown in a figure (b) by mechanisms for vertically driving the magnet roller 20-1 to 20-7, then, the 2nd color image is developed. Thereafter, when the final image area passes through the developing area of the 2nd color developing device, the magnet roller 9-2 is turned back to a position shown in a figure (a), each developing device operation is stopped. |
