Sheet conveying apparatus and image forming apparatus

A sheet conveying apparatus having a positioning mechanism provided on a sheet conveying passage, the positioning mechanism comprising;

• a reference member provided on one end of the conveying passage in a perpendicular direction to a sheet-conveying direction,
• a plurality of reference surfaces which are provided on the reference member in a stepwise manner in accordance with sizes of sheets, and which define a conveying-reference of the sheet,
• an obliquely conveying roller which is obliquely disposed on the conveying passage,
• a curved guide surface provided with an upstream side of the reference surfaces, and
• a rib which is provided on the curved guide surface and located on the opposite side from the reference surfaces with respect to a center in a direction perpendicular to a sheet conveying direction of the sheet.

A sheet conveying apparatus which again feeds a sheet whose first surface is formed with an image by an image forming section to the image forming section for forming an image on a second surface of the sheet which is opposite side from the first surface through a re-feeding passage, the sheet conveying apparatus comprising;

• a reference member provided on one end of the re-feeding passage in a perpendicular direction to a sheet-conveying direction,
• a plurality of reference surfaces which are provided on the reference member in a stepwise manner in accordance with sizes of sheets, and which define a conveying-reference of the sheet,
• an obliquely conveying roller which is obliquely disposed on the re-feeding passage,
• a curved guide surface provided with an upstream side of the reference member, and
• at least one rib which is provided at a position corresponding to one side end of a sheet whose other side end is supported by a sheet support surface which is substantially horizontally extending from each lower end of the plurality of reference surfaces, and which has substantially the same height as that of the sheet support surface.