| 摘要 |
PURPOSE:To obtain copied reproduced images according to desirable selected density by providing a control means for keeping potential difference between a developing sleeve and a toner recovering roll at a constant value by altering a recovering bias voltage. CONSTITUTION:The control means for keeping the potential difference DELTAV between the developing sleeve 4 and the toner recovering roll 9 at a constant value by altering the recovering bias voltage Vss as soon as the copied image density is adjusted by altering a developing bias voltage Vb is provided on the titled machine. Then, the potential difference DELTAV is kept constant and the quantity of supplying toner from the toner supply roll 9 to the developing sleeve 4 and the quantity of recovering toner from the developing sleeve 4 to the toner supply roller 9 are balanced and the toner concentration on the developing sleeve is kept constant. Then, in a state where the toner concentration is constant, developing is executed based on the potential difference between the developing sleeve on which altered developing bias voltage is impressed and an electrostatic latent image carrier whose electrified potential is constant. Thus, the reproduced image according to the desirable selected image density can be obtained even if the developing bias voltage is altered. |
