Image forming apparatus with geometric configuration that reduces misregistration of images

An image forming apparatus comprising:

• an annular belt looped around a plurality of rotators including a driving roller and configured to circulate along a circulation circuit with at least one straight portion that is shaped straight when viewed in an axial direction of the driving roller;
• and
• four image formers arranged along the at least one straight portion and configured to form images on an image forming target that is the belt or a recording medium transported by the belt, the four image formers being constituted by an upstream pair of image formers, and a downstream pair of image formers,
• wherein an adjacency distance along the at least one straight portion between the upstream pair of image formers adjacent to each other on the at least one straight portion is an integral multiple of an outer peripheral length of the driving roller,
• wherein an adjacency distance along the at least one straight portion between the downstream pair of image formers adjacent to each other on the at least one straight portion is an integral multiple of the outer peripheral length of the driving roller,
• wherein the adjacency distance between the upstream pair of image formers is greater than the adjacency distance between the downstream pair of image formers,
• wherein the at least one straight portion comprises a first straight portion and a second straight portion,
• wherein, when viewed in the axial direction of the driving roller, an acute angle between the second straight portion and a horizontal direction is larger than an angle of 0° or an acute angle between the first straight portion and the horizontal direction, and
• wherein a first adjacency distance between a plurality of the image formers arranged along the first straight portion is longer than a second adjacency distance between a plurality of the image formers arranged along the second straight portion.