| 摘要 |
PURPOSE:To enable superior multiple transfer performance, by controlling volume resitivity of each toner, and combining developers retaining good transferability even if an electric transfer field changes. CONSTITUTION:An electrostatic latent image formed on a photosensitive drum 1 by proper means is visualized with a developer in a developing device 16-1, and a developed toner powder image is transferred with a transfer corotron 21 onto a transfer material held on a transfer drum 19 with a gripper 20. At the second color transfer, a toner powder image developed with a developer in a developing device 16-2 is also transferred onto the transfer material with the transfer corotron 21, and the third color transfer is likewise executed. The transfer drum 19 grips the transfer material, while it rotates by the prescribed times to execute the multiple transfers of the images of the prescribed colors. The volume resistivity of the toner to be transferred first is preferably as low as possible, when only the multiple transfer is considered, but the min. resistivity needs to be >=10OMEGA.cm for the first color toner, preferably, >=10<10>OMEGA.cm. |
