Patent ID: 7349658

Claim:
An image forming apparatus comprising: a plurality of image forming stations that each have a respective first image bearing member on which a developed image of a respective one of a plurality of different colors is formed; a second image bearing member on which the developed images formed on the first image bearing members are sequentially transferred at primary transfer positions on the first image bearing members; a secondary transfer unit that transfers the developed images, transferred onto the second image bearing member, together onto a recording medium at a secondary transfer position; and a controller that selectively carries out a full-color mode in which a full-color image is formed with developers of a plurality of colors onto the second image bearing member and a monocolor mode in which a monocolor image is formed with a developer of one color onto the second image bearing member, wherein, when the controller switches between the full-color mode and the monocolor mode, the controller changes the length of a non-image forming region that does not form the full-color image and the monocolor image onto the second image bearing member, and makes a first switching state in which the full-color image or the monocolor image lies between the primary transfer position on the first image bearing member in the most downstream that transfer the image to the second image bearing member at the end among the first image bearing members and the secondary transfer position and in which the non-image forming regions simultaneously lie at the primary transfer position on the most downstream and at the secondary transfer position.