Patent ID: 8777217

Claim:
An image forming unit that forms images on sheets, comprising: a case including a carrying mechanism that conveys the sheets inside of the case; a sheet stacking device that includes: a stacking surface that is part of the case and formed on a surface of the case, and on which the sheets discharged from the case by the carrying mechanism are stacked such that the stacking surface faces an image forming surface of eace of the sheets on which the images are formed; a plurality of projections that project from the stacking surface and contact the image forming surface of the sheets, at least a pair of the projections extending generally in the travel direction of the sheets; and a trench that is formed in a portion of the stacking surface that is defined by the pair of the projections extending generally in the travel direction of the sheets with respect to a direction that is perpendicular to the travel direction of the sheets, wherein the trench is formed in a substantially linear shape extending in the travel direction of the sheets, the plurality of projections includes at least two outer projections provided so as to extend along the trench, the plurality of projections includes at least two inner projections provided in a region between the outer projections, lengths of the outer projections in the travel direction of the sheets are the same or almost the same, lengths of the inner projections in the travel direction of the sheets are the same or almost the same, and the lengths of the outer projections and the lengths of the inner projections are different.