| 摘要 |
PURPOSE:To obtain a developing device of high reliability without a image quality defect by removing toner on a toner carrier with an electric field generated between the toner carrier and a developer carrier in each developing process. CONSTITUTION:It takes about 0.5 second from the completion of a developing process to the next developing process. that is, two cycles or more of the toner carrier 68. The voltage of the developer carrier 66 is switched for the first cycle to obtain -100V. At this time. the potential difference between the toner carrier 68 and the developer carrier 66 is 100V in an absolute value and the electric field between both carriers is opposite to the forming a toner layer to bring the toner on the toner carrier 68 to a magnetic brush on the developer carrier 66. T}men, for preparing for the second developing process, the voltage of the developer carrier 66 is -400V to start the formation of the toner onto the developer carrier 68. After the second developing process is completed, the voltage to the developer carrier 66 is switched again and the toner on the toner carrier 68 is removed to bring completion. Thus, reduction in an image density and a developing history can be prevented without imparting a mechanical stress to the toner. |
