A theoretical threshold corresponding to a transport path is set, and a control unit acquires a calculation value calculated based on a detection result of double feeding detection unit and a transport length of a document, determines occurrence of double feeding when the calculation value is greater than the theoretical threshold (step S120), and determines non-occurrence of double feeding when the calculation value is smaller than the theoretical threshold. In addition, if a non-detection period for double feeding occurs (step S110), the control unit sets a cumulative value in step S115. As a result, detection of double feeding is ended in a short period while a document is being transported, and in a case that double feeding is no longer detected, determination of double feeding will not be made.

A paper sheet feeding apparatus includes an inserting unit in which a paper sheet is inserted, a pick-up roller for picking up a paper sheet inserted in the inserting unit, a rotating shaft for rotating the pick-up roller, a detecting member that is supported by the rotating shaft so as to be able to rotate around the rotating shaft and is rotated by a bundling member that bundles paper sheets together, and a first detecting unit that detects rotation of the detecting member.

A paper sheet feeding apparatus includes an inserting unit in which a paper sheet is inserted, a pick-up roller for picking up a paper sheet inserted in the inserting unit, a rotating shaft for rotating the pick-up roller, a detecting member that is supported by the rotating shaft so as to be able to rotate around the rotating shaft and is rotated by a bundling member that bundles paper sheets together, and a first detecting unit that detects rotation of the detecting member.

A medium conveying apparatus includes a suctioner that suctions a medium of a plurality of media to a feed belt, a driver that moves the feed belt to feed the medium, a first side blower that blows air at a first airflow rate to a first end face of the medium, a second side blower that blows air at a second airflow rate to a second end face of the medium, and a controller that controls the first side blower to blow air to the first end face at a third airflow rate that is greater than the first airflow rate and the second airflow rate when the medium has not been auctioned to a first portion of the feed belt close to the first end face and has been auctioned to a second portion of the feed belt close to the second end face.

In a case where a skew of a document being conveyed is detected by a detection unit, an image reading apparatus notifies that documents having different sheet widths may be included in documents stacked on a stacking unit.

In a case where a skew of a document being conveyed is detected by a detection unit, an image reading apparatus notifies that documents having different sheet widths may be included in documents stacked on a stacking unit.

A medium conveying apparatus includes a conveying roller to convey a medium, and a processor to detect transmission information of an ultrasonic wave transmitted through the medium or thickness information of the medium at a plurality of positions in the conveyed medium, calculate a size of an area in which the transmission information or the thickness information is within a predetermined range in the conveyed medium, determine whether a multi-feed of the medium has occurred, by comparing a value based on the transmission information or the thickness information with a threshold, and execute an abnormality processing when it is determined that the multi-feed of the medium has occurred. The processor changes the threshold according to the size.

A medium conveying apparatus includes a conveying roller to convey a medium, and a processor to detect transmission information of an ultrasonic wave transmitted through the medium or thickness information of the medium at a plurality of positions in the conveyed medium, calculate a size of an area in which the transmission information or the thickness information is within a predetermined range in the conveyed medium, determine whether a multi-feed of the medium has occurred, by comparing a value based on the transmission information or the thickness information with a threshold, and execute an abnormality processing when it is determined that the multi-feed of the medium has occurred. The processor changes the threshold according to the size.

A medium conveying apparatus includes a pick roller feeding a medium, a separation roller placed on a downstream side of the pick roller in a conveying direction of a medium, an arrival detection sensor placed on a downstream side of the separation roller in the conveying direction and detecting arrival of a medium, a lift sensor detecting a lift of a medium between an upstream side of a roller nip of the pick roller and a downstream side of a roller nip of the separation roller, and a processor. The processor determines that a medium is a bound medium when a lift of a medium is detected by the lift sensor in a first predetermined period after detection of a front edge of a medium in a conveying direction by the arrival detection sensor, and executes abnormality processing when a medium is determined to be a bound medium.

A medium conveying apparatus includes a conveying roller to convey a rectangular medium, and a processor to generate an input image acquired by imaging the conveyed medium, detect an overlap of the conveyed medium, detect an object area from the input image, determine whether an outer shape of the object area is rectangular, determine whether a multi-feed of the medium has occurred based on whether the overlap of the medium has been detected and whether the outer shape of the object area is rectangular, and execute an abnormality processing when it is determined that the multi-feed of the medium has occurred.