Patent ID: 7489884

Claim:
An image forming apparatus comprising: a first submodule that is used for image formation; a first phase detector that detects a phase of the first submodule; a second submodule that is used for image formation in conjunction with the first submodule; a second phase detector that detects a phase of the second submodule; a density detector that detects density of an image formed by using the first submodule and the second submodule; a correction setting section that sets a first parameter to correct non-uniformity in density in a slow-scan direction caused by the first submodule and a second parameter to correct non-uniformity in density in the slow-scan direction caused by the second submodule, based on image density data detected by the density detector; an output setting section that derives a first correction value for the phase of the first submodule detected by the first phase detector from the first parameter set by the correction setting section, derives a second correction value for the phase of the second submodule detected by the second phase detector from the second parameter set by the correction setting section, and outputs a correction value generated by merging the first correction value and the second correction value; and an imaging condition changing section that changes imaging conditions in accordance with the correction value which is output by the output setting section.