Patent ID: 7389075

Claim:
A positional error correction method for an image forming apparatus including an electrophotographic process part for image formation for an image carrying medium provided for each of a plurality of colors; a non-end moving part that moves images transferred thereto from the respective image carrying media for the respective colors; and an image detecting part that detects an image formed on said non-end moving part, wherein the respective electrophotographic process parts are disposed in sequence along said non-end moving part, and form positional error detection marks on said non-end moving part; and said image detecting part detects the thus-formed positional error detection marks, said method comprises the steps of: a) performing positional error correction based on a result of detection thus performed by said image detecting part; and b) performing at least one of a first positional error mode which uses first positional error detection marks and a second positional error mode which uses second positional error detection marks, wherein after said first positional error mode is performed, a determination is made as to whether or not said first positional error detection marks have been properly detected, and when the positional error detection marks have not been properly detected, said second positional error mode, said first positional error mode and said determination are performed in this order until said determination indicates that said first positional error detection marks have been properly detected.