| 摘要 |
PROBLEM TO BE SOLVED: To solve such a problem that the fluctuation of image density and an abnormal image such as a surface staining or a character deformation are caused by the large change of developer characteristic due to the environmental condition and image forming duty or the like. SOLUTION: This device is equipped with a developing bias correction means 18 providing upper and lower limit values to a reference value VTref on toner replenishment corrected by a reference value correction means 17 based on the output value of an image density detection means 5, and changing the value of developing bias applied to a developing part 4a with respect to a default value based on the reference value VTref and the output value of the detection means 5. |
