| 摘要 |
PROBLEM TO BE SOLVED: To provide an image forming device capable of obtaining an image with higher image quality by properly controlling the toner concentration of developer. SOLUTION: In a color printing device 1 of such a system that the quantity of toner supplied to a developing unit 3 is controlled according to the density of a toner image for control Tp, the toner concentration of the developer in the developing unit 3 is detected by a toner concentration sensor 7. Then, a target value adjustment part 8 changing the density target value of the toner image for control to a high density side when the detected value of the sensor 7 becomes equal to or under a prescribed toner concentration lower limit value and changing the control target value of the developing potential in a direction that developing potential width is enlarged when the detected value becomes equal to or over a prescribed toner concentration upper limit value is arranged. |
