| 摘要 |
PURPOSE:To enable satisfactory replenishing operation of a developer and to obviate accumulation of the developer replenished on the unagitated developer and consequent defective agitation by performing the replenishing operation of the developer only for the selected developing device at least during image forming operation. CONSTITUTION:A photosensitive drum 7 is disposed in approximately the central part of a body 1. An electrifier 8 for electrification, an optical system 9, a two-color developing device 10, an electrifier 11 for transfer, an electrifier 12 for stripping, a cleaning device 13 and a destaticizing lamp 14 are successively disposed around the photosensitive drum 7. Plural pieces of the developing devices contg. the developer, selecting means for selecting the desired developing devices among the developing devices, image forming means for forming an image on an image formig medium by using the selected developing device, detecting means for detecting the decrease of the developer in each developing device to a prescribed amt. or below and developer replenishing means for replenishing the developer to each developing device are provided. A control means which operates the developer replenishing means for the developing device when the detecting means detects the decrease of the developer in the selected developing device to the prescribed amt. or below is further provided. |
