Image forming apparatus having cleaning device of pre-secondary transfer discharge unit

An image forming apparatus comprising:

• a primary transfer unit to primarily transfer toner images of a plurality of colors onto an intermediate transfer member, each of the toner images having been formed on a rotating image carrier;
• a secondary transfer unit to secondarily transfer the toner images formed on the intermediate transfer member onto a transfer material;
• and
• a pre-secondary transfer discharge unit to discharge electrical charges of the toner images carried by the intermediate transfer member,
• wherein the pre-secondary transfer discharge unit comprises:
• a scorotron charging unit having a grid electrode disposed to face the intermediate transfer member, and a discharging electrode;
• an opposing electrode disposed to oppose the grid electrode through the intermediate transfer member;
• a first voltage applying unit to apply a voltage of reverse polarity to a charge polarity of toners forming the toner images to the discharging electrode;
• a second voltage applying unit to apply a voltage of same polarity as the charge polarity of the toners to the grid electrode;
• a cleaning unit to clean the grid electrode;
• a detecting unit to detect an electric current value flowing to the opposing electrode;
• and
• a controller to control a timing for the cleaning unit to clean the grid electrode, in accordance with the electric current value detected by the detecting unit.