A sheet feeding apparatus for feeding sheets is provided with a multi feed detecting section for detecting multi feed of conveyed sheets in a predetermined detection position of a conveyance path, and first and second discharge sections to which multi-fed sheets with the multi feed detected are discharged, and corresponding to one of a front end position of the multi-fed sheets at the time the multi feed detecting section detects the multi feed of sheets, a sheet storage state of the second discharge section, sheet storage states of the first and second discharge sections, a size of sheets and weighing, selects one of the first and second discharge sections to discharge the multi-fed sheets to the selected discharge section.

A sheet feeding apparatus for feeding sheets is provided with a multi feed detecting section for detecting multi feed of conveyed sheets in a predetermined detection position of a conveyance path, and first and second discharge sections to which multi-fed sheets with the multi feed detected are discharged, and corresponding to one of a front end position of the multi-fed sheets at the time the multi feed detecting section detects the multi feed of sheets, a sheet storage state of the second discharge section, sheet storage states of the first and second discharge sections, a size of sheets and weighing, selects one of the first and second discharge sections to discharge the multi-fed sheets to the selected discharge section.

A media feeding apparatus includes a media mounting section, a first feed roller, a media pressing section for pressing media sheets against the first feed roller, and a pressing force adjuster for adjusting the pressing force of the media pressing section. The controller sets the pressing force of the media pressing section to first pressing force and drives the first feed roller and the second feed roller in a forward rotation direction, and in a case in which the first detector detects a passage of a leading edge of the media sheet and the second detector detects no passage of the leading edge of the media sheet after predetermined first set time has passed, the controller continues the rotation of the first feed roller and the second feed roller with second pressing force of the media pressing section greater than or equal to the first pressing force.

A sheet conveying apparatus includes a tray having a plurality of sheets, a feeder to successively convey sheets stacked on the tray, a controller, and a double-feed sensor to detect double feed when the feeder conveys a plurality of sheets in an overlapping manner. When a double-feed length, which corresponds to a length, in a conveyance direction of the sheet, of a region in which the double feed has been detected by the double-feed sensor, is larger than a predetermined distance, the controller determines that the double feed has occurred. When the double-feed length is smaller than the predetermined distance and a sheet size is smaller than a predetermined size, the controller determines that the double feed has occurred. When the double-feed length is smaller than the predetermined distance and the sheet size is larger than the predetermined size, the controller determines that the double feed has not occurred.

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.

An ultrasonic apparatus includes a first ultrasonic sensor that transmits an ultrasonic wave to an object and receives the ultrasonic wave reflected by the object, a second ultrasonic sensor that transmits an ultrasonic wave to the object and receives the ultrasonic wave reflected by the object, an determination circuit that outputs an error signal when the difference between a first distance between the first ultrasonic sensor and the object calculated based on ultrasonic wave transmission and reception processing using the first ultrasonic sensor and a second distance between the second ultrasonic sensor and the object calculated based on ultrasonic wave transmission and reception processing using the second ultrasonic sensor is equal to or greater than a threshold value.

A medium conveying apparatus includes a conveying roller to convey a medium, an overlap detection sensor, a processor to detect an overlap portion in which it is determined that an overlap has occurred on the medium based on a detection output by the overlap detection sensor for the medium conveyed by the conveying roller, calculate an overlap length where the overlap portion is continuous based on a detection result of the overlap portion, determine whether a multi-feed has occurred based on the overlap length, and execute an abnormal processing for the multi-feed based on a determination result of the multi-feed. The processor determines that a first overlap portion and a second overlap portion are continuous when a distance between the first overlap portion and the second overlap portion is within a predetermined distance in calculating the overlap length.

A printing apparatus includes a feeding roller configured to feed a printing sheet stacked on a stacking unit, a conveyance roller configured to convey the printing sheet fed by the feeding roller, a printing unit configured to print the printing sheet conveyed by the conveyance roller, a conveyance control unit configured to control conveyance of printing sheets so that the trailing edge of a preceding sheet as a printing sheet precedingly fed from the stacking unit and the leading edge of a succeeding sheet as a printing sheet succeedingly fed from the stacking unit overlap each other, and a determination unit configured to determine whether to convey the succeeding sheet to a position facing the printing unit while keeping an overlap state between the preceding sheet and the succeeding sheet.

An image reading apparatus includes a control unit configured to detect occurrence or non-occurrence of multi-sheet feed of a medium based on a reception level signal output by a reception unit in accordance with the received ultrasonic wave. The control unit, after a tip of the medium reaches the positions of the reception unit in a transport path, when the reception level signal is below a predetermined threshold, causes the driving voltage to rise, when an amount of change in the reception level signal in accordance with the rise in the driving voltage is smaller than a reference amount of change, determines that multi-sheet feed is ongoing, and when the amount of change in the reception level signal in accordance with the rise in the driving voltage is greater than the reference amount of change, determines that multi-sheet feed is not ongoing.

A medium feeding apparatus includes a pickup roller that feeds a medium from a medium mount section. A support member supports a pickup roller and swings around a swing axis to switch between a feeding position and a non-feeding position. A separation roller separates the medium from other media. A feed roller feeds the medium toward the downstream end. The separation and feed rollers are disposed downstream of the pickup roller. A control section controls a position of the support member. After the pickup roller and the feed roller start rotating, when the control section determines that the separation roller stops rotating or returns the medium by rotating in a reverse direction, based on a detection signal from a rotation sensing section configured to detect rotation of the separation roller, the control section causes the support member to switch from the feeding position to the non-feeding position.