| 摘要 |
PURPOSE:To keep stable image density and image quality over a long period by correcting a toner concentration information detecting signal, with a developer density information detecting signal, and controlling the replenishment of toner. CONSTITUTION:A second detecting sensor 23 having a detecting system different from that of a reflected light quantity detecting sensor 22, is provided in the vicinity of the reflected light quantity detecting sensor 22, in order to detect the density of a developer in the vicinity of the reflected light quantity detecting sensor 22. Then, the toner concentration information of the developer is corrected, based on the reflected light quantity detected by the reflected light quantity detecting sensor 22, with an output value from the developer density detecting sensor 23, an accurate toner concentration that the effect of a change in the density of the developer is reduced, is calculated, to control the toner concentration of the developer with high accuracy. At this time, as the developer density detecting sensor 23, a known inductance sensor detecting the inductance of the developer carried and transported by a developing sleeve 4, and outputting an electric signal corresponding to the inductance is used. |
