| 摘要 |
PURPOSE:To maintain image density always constant by performing developing electrostatic field controlling according to the extent of deterioration of developing solution. CONSTITUTION:Electrodes 4 for detecting electrodeposition current of developing solution are disposed in a developing solution tank 5 and are connected to a developing electrode 8 by way of a current detecting circuit 6 and bias voltage generating circuit 7. Then, when the developing solution deteriorates upon long-term use and non-charged toner increases in the developer, the electrodeposition current flowing in the electrodes 4 decrease in proportion to the deterioration and is detected by the current detcting circuit 6. This detection output is applied to a bias voltage generating circuit 7, by which the bias voltage of the developing electrode 8 is controlled, thus the decrease in the image density owing to the deterioration of the developing solution is corrcted by the bias voltage increase of the developing electrode 8. |
