Automatic cleaning image forming apparatus and method of controlling image forming apparatus

A method of controlling an image forming apparatus including a photoconductive drum that forms a toner image, a primary transfer belt that comes in contact with the photoconductive drum and receives the toner image from the photoconductive drum, a secondary transfer counter roller, a secondary transfer roller that presses a printing medium against the primary transfer belt to transfer the toner image on the primary transfer belt to the printing medium, a bias control circuit that applies a bias to the secondary transfer roller, a belt cleaner that is in contact with the primary transfer belt and removes attached matters from the primary transfer belt, and a processor, the method comprising:

• controlling, via the processor, during an interruption of a printing operation of transferring the toner image to the printing medium, the image forming apparatus to:
• perform a forward rotation operation by the photoconductive drum, the secondary transfer counter roller, and the secondary transfer roller while applying a bias having a polarity that is opposite to that in the printing operation to the secondary transfer roller by the bias control circuit,
• perform a reverse rotation operation in a direction that is opposite to the forward rotation operation,
• restart the forward rotation operation, and
• resume or restart the printing operation.

A method for cleaning a primary transfer belt in an image forming device, the method comprising:

• rotating the primary transfer belt forward;
• applying a cleaning bias to a secondary transfer roller coupled to the primary transfer belt;
• measuring an amount of forward rotation of a primary transfer roller in contact with the primary transfer belt;
• releasing the cleaning bias of the secondary transfer roller when the amount of forward rotation of the primary transfer roller has reached a set value;
• rotating the primary transfer belt backward for a measured amount;
• determining whether the measured amount of the backward rotation has reached a threshold;
• rotating, upon determining that the measured amount of the backward rotation is greater than or equal to the threshold, the primary transfer belt forward;
• and
• removing toner on the primary transfer belt in a toner removing forward rotation operation.