Patent ID: 8446443

Claim:
An image forming apparatus comprising: an optical-path deflecting unit that deflects optical paths of optical beams in one group out of two groups, the optical beams being provided in a sub-scanning direction at a predetermined pitch, and each of the two groups being composed of more or less a same number of adjacent optical beams that are adjacent in the sub-scanning direction; a scanning unit that scans a surface to be scanned in a main scanning direction with the one group of the optical beams of which optical paths have been deflected by the optical-path deflecting unit and another group of the optical beams of which optical paths are not deflected by the optical-path deflecting unit; and a control unit that controls the optical-path deflecting unit to deflect optical paths of the optical beams in the one group so that irradiation positions of the optical beams in the one group on the surface to be scanned and irradiation positions of the optical beams in the another group on the surface to be scanned are alternately arranged in the sub-scanning direction at regular intervals, so that a plurality of pairs of the plurality of light beams are formed, each pair being composed of an optical beam in the one group and an optical beam in the another group that are positioned in the sub-scanning direction, and so that the plurality of pairs, in which the optical beams composing each pair are positioned in the sub-scanning direction in each pair, are alternately arranged in the main-scanning direction at regular intervals.