Patent ID: 8754919

Claim:
An optical writing unit, comprising a light source to project a light beam; a deflector to deflect the light beam projected from the light source; a focusing lens to focus the light beam deflected by the deflector onto a scan target, the focusing lens being long in a main scanning direction; a lens adjusting device to rotate the focusing lens about a substantially center portion thereof as a rotation fulcrum on a plane perpendicular to an optical path of the light beam so as to adjust the position of the light beam illuminating the scan target; a housing to house the light source, the deflector, the focusing lens, and the lens adjusting device; a rib disposed across the housing in the direction perpendicular to the longitudinal direction; and a positioning member to position an end portion of the focusing lens in the longitudinal direction in place with respect to the housing, the positioning member being disposed outside the rib.