| 摘要 |
PROBLEM TO BE SOLVED: To prevent poor images from occurring when a document is fed in multiplicity in a sheet-through type image reader.SOLUTION: Provided is an image reader, comprising a multi-feed detection unit for detecting whether a document is fed in multiplicity on a transport path, a surface image reading unit 50 for reading a surface image of the document, and a backside image reading unit 40 for reading a backside image of the document. When it is detected by the multi-feed detection unit that the document is fed in multiplicity, a first length L1 from the tip to the tail end of document sheets D1 and D2 is detected by a sensor SE1, a second length L2 from the tip to the tail end of the document sheets D1 and D2 is detected by a sensor SE2, and a change amount &Dgr;L is calculated from the L1 and L2. If the change amount &Dgr;L is out of a prescribed range, the surface image data and backside image data are determined to be invalid, and if the change amount &Dgr;L is within the prescribed range, the surface image data and backside image data are determined to be valid. |
