Patent ID: 8718519

Claim:
An image forming apparatus including an endless belt for formation of an image, a plurality of imaging forming units that are provided at positions different from each other along a moving direction of a peripheral surface of the endless belt and form images of different colors on the endless belt, and a sensor provided at a position on a downstream side relative to the plurality of image forming units along the moving direction of the peripheral surface of the endless belt, the apparatus comprising: a pattern forming unit that forms a plurality of pattern images of different colors on the endless belt by using the plurality of image forming units, the plurality of pattern images of the different colors being used to calculate an amount of color deviation when a plurality of images of different colors are superimposed and formed on the endless belt; a detection unit that detects, using the sensor, the plurality of pattern images formed on the endless belt by said pattern forming unit; a calculation unit that calculates the amount of color deviation from detection results on the plurality of pattern images which are obtained by said detection unit; and a correction unit that corrects color deviation in accordance with the amount of color deviation calculated by said calculation unit, wherein said pattern forming unit forms the plurality of pattern images on the endless belt by using the plurality of image forming units at first intervals which reduce, to a predetermined allowable range, a total variation of a variation of a formation position where the pattern image is formed by the image forming unit on the endless belt with respect to an ideal position and a variation of a detection position where the sensor detects the pattern image with respect to an ideal position, the variations occurring when a moving speed of the peripheral surface of the endless belt fluctuates at a specific period, and wherein each of the first intervals is shorter than a distance between an image forming unit corresponding to a reference color and an image forming unit corresponding to each color other than the reference color.