Provided is a sheet conveying device capable of suppressing the recurrence of overlapped feeding in accordance with the detection of overlapped feeding. The sheet conveying device includes a paper-supply roller and a conveying roller. A sheet-detecting unit detects a leading edge position of a sheet. An overlapped-feeding-detecting unit detects overlapped-feeding of sheets. An overlapped-feeding-distance-calculating unit, based on detection results, calculates an overlapped-feeding distance in which sheets are overlapped. A conveyance-control unit causes the paper-supply roller to stop at a timing when a position separated a set length in a sheet-conveyance direction from a sheet trailing edge reaches the paper-supply roller. The conveyance-control unit, in a case where detection of overlapped feeding by the overlapped-feeding-detecting unit occurs a plurality of times, extends the set length based on the overlapped-feeding distance.

A determining device includes an acquisition processing portion and a determination processing portion. The acquisition processing portion acquires a signal based on an ultrasonic wave emitted toward an object conveyed in a specific direction. The determination processing portion determines whether or not a first time period is equal to or larger than a predetermined first time threshold, wherein the first time period is a time period during which a level of the signal changes from a predetermined first level threshold to a second level threshold that is smaller than the first level threshold.

An image forming apparatus includes: an image forming unit configured to form an image on a sheet being conveyed on a horizontal path; and a double feed sensor configured to execute double feed detection processing of detecting a state in which a plurality of sheets being conveyed on the horizontal path are conveyed in a duplicate manner. The image forming apparatus includes a double feed detection function table, in which whether to enable or disable the double feed detection processing is set according to a type of a sheet. The image forming apparatus determines whether to execute the double feed detection processing at a time of image formation in accordance with sheet setting information including information on a characteristic of a sheet to be used for the image formation and setting information on whether to execute the double feed detection processing, and the double feed detection function table.

A medium feeding device includes an imaging unit which images a medium tip end portion from a position of facing a face of the medium on a downstream side of a nipping position of the medium using a feeding unit and a separating unit; and a determining unit which determines whether or not there is transport disorder by evaluating a state of a boundary between a path member which forms a medium transport path and a medium tip end from image data obtained by the imaging unit, in which the determining unit sets a rectangular determining region including at least a part of the boundary with respect to the image data, and determines whether or not there is transport disorder based on a length of a boundary in the determining region.

A feeding apparatus includes a feeding member, first and second conveying members, a separation member, and drive and control units. The feeding member feeds a recording material placed on a tray. The separation member and the first conveying member form a nip portion and separates recording materials at the nip portion. The second conveying member conveys a conveyed recording material. The drive unit drives at least the feeding member. The control unit controls to feed first and second recording materials such that a second recording material front edge passes the nip portion before a first recording material rear edge passes the nip portion, and controls to stop the second recording material after the second recording material front edge has passed the nip portion such that the first recording material rear edge reaches the second conveying member before the second recording material front edge reaches the second conveying member.

A sheet transport device includes a sheet transport path along which at least one sheet is transported to a nip defined by a fixing roller and a displacement roller, a sensing unit disposed on the sheet transport path, an opening and closing member that is movable between a closed position at which the sheet transport path is formed and an open position at which the sheet transport path is exposed, and a guide member that is attached to the opening and closing member and that moves by following displacement of the displacement roller in such a manner as to maintain a certain distance from the sensing unit.

A medium feeding device includes a feed roller that feeds a medium from a medium placement unit on which the medium is placed a separation roller that nips the medium between the feed roller and the separation roller to separate the medium, a motor that applies a rotational torque to the separation roller, and a control unit that controls the motor. The rotational torque is transmitted to the separation roller from the motor not via a torque limiter and the separation roller separates the medium with the rotational torque applied to the separation roller.

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.

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 multifeed detection device according to the present disclosure includes: a light source configured to irradiate a sheet with light; a light receiver configured to receive transmission light transmitted through a sheet and reflection light reflected by a sheet; and a controller configured to acquire, from the light receiver, transmission output data that is output data of the transmission light and reflection output data that is output data of the reflection light, the controller being configured to determine whether or not a multifeed of sheets has occurred based on the transmission output data and the reflection output data.