| 摘要 |
PURPOSE: To apply four housings containing a toner to add variation of the toner to a specified image by changing the activity ratio of each developing system and forming a required color. CONSTITUTION: A DC bias power source 90 impresses voltage on the donor structure 68 of a developing device 64, so that electrostatic field is established between the charge holding surface of a photoreceptor belt 10 and the donor structure 68 in order to restrain the adhesion of the toner to a discharge area on the charge holding surface. A bias similar to the bias impressed on the developing system 64 is impressed on an electrode 86 and the donor structure 68 of the developing system 64 so as to adhere the yellow toner electrified to be positive to the electrified area. Under the control of an electronic sub system 92, the developing systems 62 to 66 are synchronously actuated, and the activity ratio is decided according to the color selected by a user from a color palette 94 being a part of a control panel. The activity ratio is varied to 0-8mm/sec in accordance with the color by the structure of a developing unit. |
