Duplex printing apparatus with a storage section for storing a plurality of sheets

A duplex printing apparatus, comprising:

• first printing means for printing on first sides of sheets;
• a storage section for storing a plurality of the sheets, the first sides of which have been printed on;
• second printing means for printing on second sides of the sheets;
• first conveying means for sequentially conveying the sheets, the first sides of which have been printed on, to the storage section;
• and
• second conveying means for sequentially conveying the plurality of sheets which are stored at the storage section to the second printing means;
• the storage section being equipped with a holding mechanism that holds the plurality of sheets, the first sides of which have been printed on, in an overlapped state with predetermined intervals therebetween;
• wherein:
• the holding mechanism is equipped with a bottom edge supporting means, for supporting the bottom edges of each of the plurality of sheets with predetermined intervals therebetween such that they are held in an upright state, and curl imparting means, for imparting curls to the sheets such that they are curled with the first sides thereof having a concave shape in horizontal cross sections;
• the storage section has a sheet insert position, at which the sheets which are conveyed by the first conveying means enter the storage section, and a sheet discharge position, at which the stored sheets are passed on to the second conveying means;
• the sheet insert position and the sheet discharge position are spaced a predetermined distance apart from each other;
• and
• the holding mechanism sequentially holds each of the sheets that enter the storage section from the sheet insert position, and moves each of the sheets toward the sheet discharge position, while the sheets are in an overlapped state with predetermined intervals therebetween.