Sheet transfer apparatus having a light volume detection means for detecting a deviation amount of a sheet and image reading apparatus having the sheet transfer apparatus

An image reading apparatus for reading an image of a sheet to be transferred to a prescribed read position, comprising:

• a feed tray capable of placing sheets of a plurality of sizes in which a length in a width direction of the sheet perpendicular to a transfer direction of the sheet is different;
• a discharge device for storing sheets read at said read position;
• a transfer means for transferring the sheet placed on said feed tray to the prescribed read position;
• a reading means for reading the image of the sheet transferred by said transfer means at said read position,
• a light volume detection means arranged upstream in the transfer direction of said read position to detect a light volume according to a deviation amount at a sheet transfer position in the width direction of a sheet end to be transferred, and
• an operation means for calculating the deviation amount with respect to a reference position of said sheet transfer position on a basis of an output signal of said light volume detection means,
• wherein said light volume detection means comprises a light emitting means and a light receiving means having a light receiving surface of a prescribed length in the width direction of the sheet, and said light receiving means is arranged on an opposite side of said light emitting means with a sheet transfer channel interposed, and wherein said light emitting means comprises a plurality of elements which is positioned in the width direction of the sheet on said feed tray while said light receiving means is movable with respect to the plurality of elements according to the sizes of the sheets.