Sheet feeding apparatus, image reading apparatus equipped with the same, and method of detecting double feed

摘要

A sheet feeding apparatus includes a sheet size recognition device for recognizing length of a sheet placed on a stacker in a transport direction, an ultrasonic double feed detection device arranged between a first transport device and a second transport device for detecting a double feed of sheets, and a transport length detection device for detecting a transport length of the sheet transported by the first and second transport devices from a leading edge of the sheet to a trailing edge of the sheet. A comparison device compares the length of the sheet recognized by the sheet size recognition device and the transport length of the sheet detected by the transport length detection device. A judgment device judges the double feed of the sheets based on at least one of a comparison result from the comparison device and a detection result from the double feed detection device.