| 摘要 |
PURPOSE:To control toner concentration correctly by altering a reference level for controlling toner concentration and a reference output for adjustment, depending on whether developing units whose toner concentrations are not controlled and which affect output values and detecting values of toner concentration sensors in target developing units for controlling toner concentration are present or not. CONSTITUTION:The comparison reference level for controlling the toner concentration in the developing units 8, 10 and 12 is altered according as the developing devices not used currently, which affect the values detected by the toner concentration sensor 40, 41 and 42 mounted on the developing units 8, 10 and 12, are present or not. A reference output for adjusting outputs from the toner concentration sensors 40, 41 and 42 when the title device starts operation initially and when fresh developer is fed is altered, depending on whether the developing units not used currently and affecting out-puts from the sensors 40, 41 and 42 are present or not. As a result, toner concentration and outputs from the toner concentration sensors can be controlled and adjusted in a desired manner. |
