Patent ID: 7593665

Claim:
An image forming apparatus, comprising: a toner image forming unit to form a toner image on an image bearing member by employing toner; an intermediate transfer member driven to rotate; a primary transferring unit to transfer said toner image formed on said image bearing member onto said intermediate transfer member; a secondary transferring unit to transfer said toner image residing on said intermediate transfer member onto a transfer material; and a cleaning unit to clean residual toner remaining on said intermediate transfer member; wherein said cleaning unit includes: a conductive opposing roller that contacts an inner surface of said intermediate transfer member; a first conductive brush member and a second conductive brush member, both of which are pressed against said conductive opposing roller while putting said intermediate transfer member between them; an electric current path that is formed so as to allow an electric current to flow between said first conductive brush member and said second conductive brush member through said conductive opposing roller; a cleaning-voltage applying power source to apply a cleaning voltage having a polarity opposite to that of said residual toner onto said first conductive brush member or said second conductive brush member; and an opposing-roller potential controlling unit to control an electric potential state of said conductive opposing roller, so that an electric potential difference, between said first conductive brush member and said conductive opposing roller at a time when said secondary transferring unit is deactivated, is larger than that at a time when said primary transferring unit is activated.