| 摘要 |
PROBLEM TO BE SOLVED: To provide an image forming device capable of restraining or preventing a surface staining in a specific width occurring in the vicinity of the image part derived from deterioration of the developer. SOLUTION: The device detects the peak value by detecting a density of a non-image part by a P sensor 7 (step 1 and 2), after producing a reference pattern on a photoreceptor drum 1. In the case detecting frequency of the peak value becomes twice, it is judged that the surface staining of a specific width is generated (step 3). The ratio Vsp1/Vsg between the density detection value Vsp1 of the surface staining generation part and the set output Vsg is judged whether smaller than 0.6 or not (step 4). In the case of smaller than 0.6, by judging that change of the developer is necessary, an agent replace display not shown in the figure on the operation display part of a copying machine is turned on (step 5). |
