IMAGE FORMING APPARATUS

摘要

An image forming apparatus calculates a positional deviation in the main and sub-scanning directions for each color by forming registration patterns in two arrays along a sub-scanning direction on an image carrier. Each registration pattern in one array is paired with an identical registration pattern in the other array. A first sensor has: a light-emitting element irradiating one registration pattern in a pair; a photodetector for regular reflection light; and a photodetector for diffuse reflection light. A second sensor has: a light-emitting element irradiating the other one in the pair; and a photodetector for regular reflection light. The relative positions of a pair of registration patters calculated using the respective sensors are corrected so as to reduce the positional deviation between the calculated positions by the amount of offset deviation estimated occur between positions detected by the respective sensors when the registration patterns are without positional deviation.