| 摘要 |
PURPOSE:To obtain a copy having a satisfactory and high picture quality, by applying AC bias voltage and DC bias voltage to a magnetic brush roll for executing development at first, and a magnetic brush roll for executing development finally, respectively, in plural pieces of magnetic brushes. CONSTITUTION:To the first magnetic brush roll 12 for developing the latent image charge on a latent image carrying body 1, AC bias voltage is applied by an electric power supply 9. Subsequently, as for the second magnetic brush roll 11 for executing development finally in a developing area B2, an unnecessary toner which has adhered to the background part is attracted closer to the second magnetic brush roll 11 side in reverse, by use of a method for applying the bias voltage having the same polarity as the latent image charge higher enough than the background potential by a DC power supply 10. Subsequently, a cleaning operation of the background is executed, by which it is possible to obtain a copy having high picture density and a satisfactory and high picture quality. |
