Patent ID: 7434905

Claim:
An image forming apparatus that carries out color image formation by primarily transferring an image formed on a photosensitive body onto a rotatably driven intermediate transfer member and secondarily transferring the image on the intermediate transfer member onto a recording medium, comprising: a reference position detecting device that detects a reference position on the intermediate transfer member; a first issuing device that issues an image writing reference position signal for starting image formation, irrespective of detection of the reference position on the intermediate transfer member; a second issuing device that issues the image writing reference position signal for starting image formation based on the detected reference position on the intermediate transfer member; and a selection device that controls the image formation based on the signal issued by said first issuing device in a case where the processing speed of the image formation is not changed during the image formation, and controls the image formation based on the signal issued by said second issuing device in a case where the processing speed of the image formation is changed during the image formation.