Image forming apparatus and method of controlling same

An image forming apparatus, comprising:

• a single first image carrier on which different color toner images C are formed and superimposed one on another to form a multicolor toner image A
• a transfer fixing member onto which the toner image A consisting of the toner images C is transferred;
• a heater configured to fuse the toner image A on the transfer fixing member;
• a pressurizer pressing against the transfer fixing member, configured to form a nip, together with the transfer fixing member, in which the fused toner image A is transferred from the transfer fixing member and fixed on a recording medium;
• an image carrier located upstream of the transfer fixing member in a direction in which the recording medium is transported, on which a toner image B whose color is different from a color of the toner image A is formed;
• and
• a transferer facing the image carrier, configured to transfer the toner image B onto the recording medium before the toner image A is transferred thereonto,
• wherein the toner image B is fixed by the transfer fixing member and the pressurizer on the recording medium.

A control method of an image forming apparatus, the image forming apparatus comprising:

• at least one first image carrier on which a toner image C is formed;
• a second image carrier;
• a transfer fixing member onto which a multicolor toner image A including the toner image C is transferred from the second image carrier;
• and
• a third image carrier,
• the control method comprising:
• forming a toner image B on the third image carrier;
• transferring the toner image B onto a recording medium at a position upstream of the transfer fixing member in a direction in which the recording medium is transported;
• fixing the toner image B on the recording medium in a nip formed between the transfer fixing member and a pressurizer pressing against the transfer fixing member;
• and
• disengaging the second image carrier from the transfer fixing member during single color image formation,
• wherein a color of the toner image B is different from a color of the multicolor toner image A.