| 摘要 |
PURPOSE:To obtain a copied picture at a certain density level without fail, irrespective of a change in the output characteristic of a toner density sensor, which is caused by a change in copy attitudes such as single printout and continuous printouts, by adjusting a picture density in accordance with the operation rate of a developing unit. CONSTITUTION:A picture area developing time counter 12 counts the product of a set time necessary for development and the number of copies, while a developing unit drive time counter 10 integrates the time when the developing unit is driven based on the number of copies. When the number of copies attains the set value, a developing unit operation rate calculating circuit 14 calculates the ratio of the developing time to the total operating time of the developing unit, that is, the operation rate of the developing unit, and outputs data on the charged situation of toner in the developing unit to a reference voltage adjuster 5, which corrects the hourly fluctuation of the level of a signal from the toner density sensor 2 based on a change in toner's charged amount. |
