| 摘要 |
PURPOSE:To prevent adhesion of paper dust, matters produced by discharging, etc., which give adverse influences to a photosensitive body to the photosensitive body by controlling the adhesion of toner to a no-picture part on the photosensitive body by adjusting the bias voltage of a developing roll while a non-contacting type developing device is brought near to the photosensitive body. CONSTITUTION:When the 1st developing device 1 is set to a developing state and performs non-contacting development, a bias switching device 5 is connected with a DC power source 7 and a developing bias voltage is applied across the developing roll 3. Upon performing the non-contacting development, the device 1 can cause a very small quantity of toner to adhere to a no-picture part on the photosensitive body. When development is performed with a developing device having a less quantity of a developing agent adhering to the no-picture part on the photosensitive body, the bias voltage applied across the developing roll is adjusted while the non-contacting developing device 1 not participating to the development is brought near to the photosensitive body 11. Therefore, the vary small quantity of toner can be adhered to the no-picture part preferentially without giving any adverse influence to the picture obtained by main development so that adhesion of paper dust, matters produced by discharging, etc., to the surface of the photosensitive body can be prevented. |
