| 摘要 |
PROBLEM TO BE SOLVED: To prolong the life of an image carrier at the time of forming an image in monochrome (at the time of outputting a black-and-white image) while securing image quality at the time of forming an image in plural colors (at the time of outputting a full color image) in an image forming device capable of forming a toner image by an image forming process including a stage for electrifying the surface of the image carrier in a contact state by an AC electrifying system in which an AC voltage component and a DC voltage component are applied as electrifying bias and selecting a mode for forming the image in monochrome and a mode for forming the image in plural colors. SOLUTION: The applying condition of the AC voltage component in the contact electrification is switched between the mode for forming the image in monochrome and the mode for forming the image in plural colors. In the case of forming the image in the monochrome, the surface of the image carrier is electrified by a DC electrifying system in which only the DC voltage component is applied as the electrifying bias without applying the AC voltage component. |
