| 摘要 |
PROBLEM TO BE SOLVED: To prevent the back surface staining of transfer paper by providing a contact electrode consisting of a rotating body for applying voltage having a reverse polarity to that of transfer voltage in order to control charges on a dielectric belt. SOLUTION: A roller 4 functions as a 1st contact electrode for a transfer belt 3 and is connected to a bias power source 6 for setting potential at which toner carried on a photoreceptor drum 2 is electrostatically attracted. A backup roller 7 arranged on the back surface side on the downstream side of the transfer position of the belt 3 constitutes a 2nd contact electrode for the belt 3. When it is assumed that the potential by electrification of the roller 4 and the roller 7 is -2 to 3 kV when the potential by electrification of photoconductivity on the drum 2 is -800 V and the electrification polarity of the toner carried on the drum 2 is a positive pole (+), the range of the bias acting on the belt 3 extends from a position where the roller 4 is opposed to the drum 2 and a position where the roller 7 is opposed thereto. |
