| 摘要 |
PURPOSE:To accurately set the reference signal of a toner concentration detecting sensor by correcting the control voltage of the toner concn. detecting sensor by the raising of a toner concn. predicted from the quantity of a recycled toner returned to a developing means from a toner recycling means. CONSTITUTION:The output signal of the toner concn. detecting sensor 106 is converted into a voltage corresponding to the toner concn. by a voltage converting part 31, amplified by an amplifier 32 and compared with the reference signal outputted from a memory part 34 via a CPU by a comparator 33, to be stored in the memory part 34. The compared value is sent to a driver circuit 35 via the CPU, to control motors M1 and M2. When toner is recycled from a cleaning device to j developing part by a toner recycling device, the concn. of the toner in the developing part is raised. Then, the output voltage of the toner concn. detecting sensor 106 is dropped so that the control voltage is dropped to keep the output voltage constant. |
