| 摘要 |
PURPOSE:To accurately detect the quantity of a developer, especially the concentration of the developer by selecting a developer quantity detecting means corresponding to the paper width of copying paper to be used and another developer quantity detecting means arranged in the paper width of a consumed copying paper to detect the quantity of the developer. CONSTITUTION:If B4-side paper is selected as copying paper, sensors 20a, 20c are used. The two sensors 20a, 20c are alternately switched to driven and disabled states every copying paper to prevent the generation of misdetection when the copying of an original in which toner consumption in a detecting area of one sensor is different from that in an area other than the sensor detecting area is continued. Since the sensors are arranged on the area in which the developer can be always consumed by selecting a toner concentration detecting member 20b/20d in accordance with the paper width of the copying paper, uniform and proper toner concentration detection always corresponding to developing can be attained. Consequently stable toner concentration control can be attained. |
