| 摘要 |
PURPOSE:To prevent the occurrence of failure caused by the erroneous detection of toner concentration just after an image formation is started by controlling the replenishing quantity of toner with a value that a prescribed correction value is added to the detection value of the toner concn. for a specified time after the detection of the image is started. CONSTITUTION:The output signal of a toner concentration sensor 21 detecting the mixing ratio of a carrier to the toner in a developer in a developing unit is inputted to a control part 13 via an A/D converter 33. A control part 31 decides the replenishing quantity of the toner by the difference between the output value of the toner concentration sensor 21 and a reference value and controls a toner supplying motor 35 in a toner supplying device via a driver 34 so as to replenish the toner to a developing unit by the decided replenishing quantity. At this time, the control part 31 controls the replenishing quantity of the toner in such a manner that the prescribed correction value is added to the output value of the toner concentration sensor 21 for the specified time just after the image is started to form. Thus, such a failure that the staining of th image on an image carrier, etc., are caused by excessive replenishment at the unstable output value of the toner concentration sensor 21 just after the formation of the image is started, can be prevented. |
