| 摘要 |
PURPOSE:To appropriately control various bias and to maintain image of high definition by temporarily setting a developing bias to be in the vicinity of the surface potential of an image carrier and variably controlling that developing bias setting. CONSTITUTION:Surface potential sensors SY to SBK detecting the surface potential of image carriers 14Y to 14BK are placed downstream of developing means 16Y to 16BK with allowance in space. Then the developing dias is temporarily set to the vicinity of the surface potential of the image carriers 14Y to 14BK, and the developing bias is variably controlled. Thus, influence of toner discharge and developing bias can be eliminated in the developing means 16Y to 16BK generated by environmental change, etc., of the developer can be eliminated, and the detection of the surface potential of the image carriers 14Y to 14BK can be carried out accurately. As the result, even when the characteristic of the image carriers 14Y to 14BK are varied environmental or economically, image forming condition can be appropriately controlled according to the change. |
