Image forming apparatus that corrects image forming positions

An image forming apparatus comprising:

• an image forming unit including a plurality of color image forming units and a black image forming unit, the plurality of color image forming units including a plurality of photosensitive members on which color toner images of different colors are respectively formed, the black image forming unit including a photosensitive member on which a black toner image is formed;
• an intermediate transfer member to which the color toner images and the black toner image are transferred;
• a transfer unit that transfers the color toner images and the black toner image from the intermediate transfer member to a sheet;
• a mechanical mechanism that controls a contact state between the plurality of photosensitive members of the plurality of color image forming units and the intermediate transfer member and between the photosensitive member of the black image forming unit and the intermediate transfer member, the contact state including:
• a first contact state in which the photosensitive member of the black image forming unit is in contact with the intermediate transfer member and the plurality of photosensitive members of the plurality of color image forming units are separated from the intermediate transfer member;
• and a second contact state in which the plurality of photosensitive members of the plurality of color image forming units and the photosensitive member of the black image forming unit are in contact with the intermediate transfer member;
• a fixing unit that fixes the color toner images and the black toner image on the sheet;
• a reading unit that reads a test image on a sheet formed by the image forming unit;
• and
• a controller configured to
• based on a reading result of the test image by the reading unit, generate data that is used to adjust image forming positions of toner images to be formed by the image forming unit,
• control an image forming position of a first toner image to be formed by the image forming unit in the first contact state based on first data, the first toner image being transferred to a first sheet, and
• control an image forming position of a second toner image to be formed by the image forming unit in the second contact state based on second data that is different from the first data, the second toner image being transferred to a second sheet, wherein a type of the second sheet is a same type as a type of the first sheet.