Patent ID: 7444098

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 first cleaning unit to remove residual toner remaining on said image bearing member after a primary transferring operation is completed; a secondary transferring unit to transfer said toner image residing on said intermediate transfer member onto a transfer material; a second cleaning unit to clean residual toner remaining on said intermediate transfer member, wherein said second cleaning unit includes a first brush roller and a second brush roller disposed at a position downstream from said first brush roller in a moving direction of said intermediate transfer member, each of which is driven to rotate while contacting said intermediate transfer member so as to clean said intermediate transfer member; and a controller to control a voltage to be applied to said first brush roller and a voltage to be applied to said second brush roller, and to control said primary transferring unit; wherein said image forming apparatus is provided with a first mode in which image forming operations based on normal image data are conducted and a second mode in which patch image forming operations based on patch image data are conducted; and wherein, in said first mode, said controller applies a voltage having a negative polarity to said first brush roller, a voltage having a positive polarity to said second brush roller and a voltage having a predetermined polarity to said primary transferring unit, respectively, while in said second mode, said controller applies a voltage having a positive polarity to said first brush roller, a voltage having a positive polarity to said second brush roller and a voltage having a positive polarity to said primary transferring unit, respectively.