Color image forming apparatus

A color image forming apparatus comprising:

• an intermediate transfer belt having a movable surface;
• a first image forming unit for forming a first toner image of a first color on the intermediate transfer belt at a first image-forming position;
• a second image forming unit for forming a second toner image of a second color to superimpose on the first toner image formed on the intermediate transfer belt at a second image-forming position, the second image forming unit being disposed downstream of the first image forming unit with respect to a moving direction of the intermediate transfer belt, the second image-forming position being spaced from the first image-forming position by a predetermined distance P;
• a third image forming unit for forming a third toner image of a third color to superimpose on the first and the second toner images formed on the intermediate transfer belt at a third image-forming position, the third image forming unit being disposed downstream of the second image forming unit with respect to the moving direction of the intermediate transfer belt, the third image-forming position being spaced from the second image-forming position by the distance P;
• a fourth image forming unit for forming a fourth toner image of a fourth color to superimpose on the first, the second and the third toner images formed on the intermediate transfer belt at a fourth image-forming position, the fourth image forming unit being disposed downstream of the third image forming unit with respect to the moving direction of the intermediate transfer belt, the fourth image-forming position being spaced from the third image-forming position by the distance P;
• and
• a transfer roller for transferring the superimposed toner images formed on the intermediate transfer belt onto a sheet, the transfer roller having a circumferential length equal to the distance P.