| 摘要 |
PURPOSE:To obtain an image with proper density by supplying toner to a 1st developing unit which controls image density and adjusting the toner concentration when a decrease in the image density or an image density decreasing state is detected. CONSTITUTION:When a detecting means 18 detects the toner concentration of the 1st developing unit decreases below a specific reference value, a toner supplementing means 21 supplements toner to the 1st developing unit 10 according to a 1st control mode. Further, when a measuring means 8 or 80 measures the decrease in the image density or a state wherein a picture element which affects the image density causes a decrease in the image density, the toner supplementing means 21 supplements toner to the 1st developing unit 10 according to a 2nd control mode. Thus, an image with proper density which is neither too thick nor too thin is obtained. |
