A line head, an exposure method using the line head, and image forming apparatus, an image forming method and a line head adjustment method

摘要

A line head (29), includes: an element substrate (293) that includes luminous element groups (295) as groups of a plurality of luminous elements (2951); and a lens array (299) that includes lenses which have an optical property of inverting or non-unity-magnification, focus light from the luminous element groups to form spot groups on an image plane, and are provided corresponding to the respective luminous element groups, wherein the plurality of luminous elements (2951) are two-dimensionally arranged in point symmetry in each luminous element group (295), a plurality of spots (SP) are formed as the spot group (SPG) when the respective luminous elements of the luminous element group emit light, and an inter-point distance between an intersection of a line extending from a symmetry center (SC) of the luminous element group in an optical axis (OA) direction of the lens with the image plane and a center of gravity position of the spot group is shorter than a specified distance.