| 摘要 |
PURPOSE:To keep image density and the toner concentration of developer constant. CONSTITUTION:In the case that the toner concentration is within a specified range based on the result of the detection of the toner concentration by a developer concentration sensor (F sensor) 118, a toner replenishment control circuit 122 controls toner replenishment based on the result of the detection of a reference toner image, which is formed by performing specified processing to a photosensitive body 101, by an optical sensor (P sensor) 106. Meanwhile, in the case that the toner concentration is out of the specified range the toner replenishment is controlled based on the result of detection by the F sensor 118, and further a magnetic roller revolving speed control circuit 120 controls the rotating speed of a magnetic roller 113 so that the image density may be kept appropriate. |
