Image forming apparatus with cleanable transfer roller

An image forming apparatus, comprising:

• a photosensitive body on which a toner image is to be formed;
• a transfer roller spaced away from an outer surface of the photosensitive body by a specified distance for transferring a toner image formed on the photosensitive body to a sheet;
• a transfer timing detector for detecting a non-image transfer period;
• a transfer output applier for applying a transfer output to the transfer roller;
• a transfer output setter, responsive to the transfer timing detector, for alternately setting a polarity of the transfer output, applied to the transfer roller by the transfer output applier, at positive and negative polarities during a detected non-image transfer period;
• and
• a transfer output controller, responsive to the transfer output setter, for controlling the transfer output applier to apply the transfer output to the transfer roller at alternate polarities set by the transfer output setter thereby repelling toner having both polarities from the transfer roller.