Patent ID: 8543020

Claim:
An image forming apparatus, comprising: an endless transport member; a plurality of image forming units including a plurality of image bearing members arranged along a moving direction of the endless transport member, each of the image bearing members forming images of one of multiple colors using electrophotography, the images transferable to the endless transport member, each of the image forming units useable as a pattern forming unit to form a plurality of correction-use patterns for each color on the endless transport member; a pattern detector, disposed near the endless transport member, to detect the correction-use patterns formed on the endless transport member by directing a light beam onto the correction-use patterns formed on the endless transport member, the pattern detector capable of detecting regular reflected light and diffuse reflected light reflecting from the endless transport member and the correction-use patterns formed on the endless transport member; an image misalignment detector to detect image misalignment of the correction-use patterns formed on the endless transport member based on a detection result of the correction-use patterns obtained by the pattern detector; and a rotatable multi-faced mirror to optically scan the image bearing member, wherein the pattern forming unit forms at least a reference color pattern and a first color pattern as correction-use patterns, each of the reference color pattern and the first color pattern being formed as a developed image, the pattern detector uses an irradiation light having a first wavelength matched to a spectral sensitivity peak of the first color pattern to detect an intensity of light reflected from the endless transport member having the reference color pattern and the first color pattern formed thereon, the image misalignment detector computes an image misalignment value between two color images of the reference color pattern and the first color pattern, based on the intensity of reflected light reflected from the reference color pattern and the first color pattern as detected by the pattern detector, and the rotatable multi-faced mirror uses a first reflection face for exposing the reference color pattern and a second reflection face opposing the first reflection face for exposing other color patterns, wherein one of: the first wavelength corresponds to red light and the first color pattern includes a cyan pattern, the first wavelength corresponds to green light and the first color pattern includes a magenta pattern, and the first wavelength corresponds to blue light and the first color pattern includes a yellow pattern.