Auto document feeding device

An image reading apparatus comprising:

• a first image reading unit configured to read an image of a first surface of a traveling original document;
• a first conveying path configured to reach from a document placing unit to the first image reading unit, the first conveying path including a first reversing unit formed in an arc shape, the first conveying path being an OUT path including the first reversing unit;
• a second conveying path configured to reach from the document placing unit to the first image reading unit and have a path different from the first conveying path, the second conveying path having a second reversing unit formed in an arc shape, the second conveying path being an IN path including the second reversing unit having a radius smaller than a radius of the first reversing unit;
• a gate unit configured to direct original documents, which are sent from the document placing unit, to either the first conveying path or the second conveying path, the gate directing the original document to the OUT path when the original document has a thickness equal to or larger than a fixed thickness;
• a document conveying unit includes a first conveyance mode which conveying the original documents with overlap a trailing edge of a preceding original document and a leading edge of a following original document, when the gate unit alternately directs the original documents from the document placing unit, to the first conveying path or the second conveying path;
• a separating unit configured to separate the overlap of the trailing edge of the preceding original document and the leading edge of the following original document before the leading edge of the following original document reaches the first image reading unit;
• and
• a paper discharging unit configured to discharge the original document that finishes passing through the first image reading unit.

An auto document feeding method comprising:

• directing original documents, which are sent from a document placing unit, to plural conveying paths;
• directing, when the original document sent from the document placing unit has a thickness equal to or larger than a fixed thickness, the original document to any one conveying path having a larger radius of a reversing unit among the plural conveying paths;
• conveying a preceding original document and a following original document, which are directed to the plural conveying paths, in a direction of, a first image reading unit with overlap a trailing edge of a preceding original document and a leading edge of a following original document;
• and
• separating the overlap of the trailing edge of the preceding original document and the leading edge of the following original document before the leading edge of the following original document reaches to the first image reading unit.