Image forming apparatus with a feeding unit including a plurality of ribs

An image forming apparatus comprising:

• an image forming unit configured to form an image on a sheet being fed;
• a turn-around mechanism configured to turn around a feeding direction of the sheet with a first image formed on a first face thereof by the image forming unit;
• and
• a re-feeding unit configured to re-feed, to the image forming unit, the sheet after the feeding direction is turned around by the turn-around mechanism, such that the image forming unit can form a second image on a second face opposite to the first face of the sheet, the re-feeding unit comprising:
• a first feeding unit comprising a guide curved to bulge in such a direction as to be farther from the image forming unit, the guide defining an outer side of a curved first feeding route configured to feed the sheet received from the turn-around mechanism downstream in the feeding direction;
• and
• a second feeding unit defining a second feeding route configured to feed the sheet fed via the first feeding route, to an upstream side of the image forming unit in the feeding direction, the second feeding unit comprising a regulating member configured to define a first side of the second feeding route in a width direction perpendicular to the feeding direction of the sheet and to regulate a position of an end of the sheet on the first side of the second feeding route in the width direction,
• wherein the guide of the first feeding unit comprises:
• a first section on the first side thereof in the width direction;
• and
• a second section on a second side opposite to the first side thereof in the width direction, the second section being curved to bulge more than the first section in such a direction as to be farther from the image forming unit;
• wherein the guide of the first feeding unit further comprises a plurality of ribs arranged in the width direction and formed to protrude toward the image forming unit in a protruding direction, the plurality of ribs comprising:
• a first-side outermost rib that is an outermost rib on the first side of the guide in the width direction, wherein a concave-most portion of a distal end surface of the first-side outermost rib is closest to the image forming unit in the protruding direction among all concave-most portions of distal end surfaces of the plurality of ribs;
• a second-side outermost rib that is an outermost rib on the second side of the guide in the width direction, wherein a concave-most portion of a distal end surface of the second-side outermost rib is farthest from the image forming unit in the protruding direction among all the concave-most portions of the distal end surfaces of the plurality of ribs,
• wherein the first section of the guide comprises a plurality of first ribs of the plurality of ribs, the plurality of first ribs including the first-side outermost rib,
• wherein the second section of the guide comprises a plurality of second ribs of the plurality of ribs, the plurality of second ribs including the second-side outermost rib, and
• wherein concave-most portions of distal end surfaces of the plurality of second ribs are farther from the image forming unit in the protruding direction than concave-most portions of distal end surfaces of the plurality of first ribs;
• and wherein the plurality of ribs have respective different protruding lengths from a base of the respective rib to the concave-most portion of the distal end surface of the respective rib, such that the protruding lengths become smaller for each subsequent rib arranged towards the second side from the first side in the width direction.