Patent ID: 7548709

Claim:
A transfer unit, comprising: an intermediate transfer member that (i) holds a toner image that has been transferred, at a primary transfer part, from a toner image holding member and (ii) rotates to move a toner image holding surface holding the toner image; a secondary transfer member that comes into contact, at a secondary transfer part, with the intermediate transfer member; and intermediate transfer member cleaning means for removing and collecting toner from the toner image holding surface of the intermediate transfer member, the transfer unit transferring the toner image from the intermediate transfer member to a sheet conveyed to the secondary transfer part formed between the intermediate transfer member and the secondary transfer member, wherein the transfer unit further comprises, secondary transfer member cleaning means for sequentially applying, to the secondary transfer member, (i) a first voltage for generating an electric field that transfers normally-charged toner from the secondary transfer member to the intermediate transfer member and (ii) a second voltage for generating an electric field that transfers oppositely-charged toner from the secondary transfer member to the intermediate transfer member, and intermediate transfer member displacing means for bringing the intermediate transfer member into contact with the toner image holding member or separating the intermediate transfer member from the toner image holding member, wherein the intermediate transfer member displacing means separates the intermediate transfer member from the toner image holding member while the secondary transfer member cleaning means is applying one of the first voltage and the second voltage to the secondary transfer member.