| 摘要 |
PURPOSE:To control the concentration of a toner with high precision by stopping, supplying interruptedly, or supplying continuously the toner in accordance with the detected value of the toner concentration of a mixture of the toner and a carrier in a developing part. CONSTITUTION:The value of the current flowed to a mixture 13 of the toner and the carrier in a developing part 2 which develops an electrostatic latent image on a photosensitive drum 1 is obtained to detect the quantity of the toner in the mixture by a current detecting circuit 9. The detected current value is inputted to a microcomputer 12 through an upper limit detector 10 and a lower limit detector 11; and if it exceeds the upper limit level, an output port is controlled to stop turning of a sponge roll 8, and the supply of a toner 4 is stopped. If the current value is smaller than the upper limit value and is larger than the lower limit value, the sponge roll 8 is driven interruptedly to supply the toner 4 interruptedly; and if the current value is smaller than the lower limit value, the sponge roll 8 is driven continuously to supply the toner 4 continuously. Thus, the quantity of the toner 4 is controlled correctly to perform copying with proper density. |
