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.

The present invention is to provide a sheet conveying apparatus capable of reliably detecting a full-load state of a storage section for storing sheets discharged from a sheet conveyance path when an abnormality such as multi feed is detected, a sheet feed apparatus is provided with a multi feed sheet storage section disposed below a common conveyance path to store multi-fed sheets with multi feed detected, and a flap member rotating between a first rotation position for supporting a sheet in the common conveyance path to be able to convey to the downstream side in a conveyance direction, and a second rotation position for guiding to the multi feed sheet storage section, and determines that the multi feed sheet storage section is in a full-load state in detecting that the flap member does not return to the first rotation position.

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 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 medium conveying apparatus includes a conveying roller to convey a medium, a width detection sensor for detecting a width of the medium conveyed by the conveying roller in a direction perpendicular to a conveying direction, an overlap detection sensor for detecting an overlap of the medium conveyed by the conveying roller, and a processor to determine whether to execute an abnormality processing for a multi-feed, based on the width of the medium acquired based on a detection result by the width detection sensor and a detection result by the overlap detection sensor. The processor acquires an overlap detection width being a width in which the medium is estimated to overlap in the direction perpendicular to the conveying direction, based on the detection result by the overlap detection sensor. The processor executes the abnormality processing when the width of the medium and the overlap detection width are equal.

A medium conveying apparatus includes a conveying roller to convey a medium, an end detection sensor for detecting a position of an end of the medium conveyed by the conveying roller, an overlap detection sensor for detecting an overlap of the medium conveyed by the conveying roller in a detection area, and a processor to determine whether an overlap detection is valid or invalid based on a positional relationship between the position of the end of the medium detected by the end detection sensor and the detection area, and execute an abnormality processing for multi-feed based on a detection result by the overlap detection sensor when it is determined that the overlap detection is valid.

When a medium detector detects that a state where a medium is absent is switched to a state where the medium is present with a light quantity of the medium detector set to a first light quantity, a controller in an image reading apparatus switches the light quantity from the first light quantity to a second light quantity, which is larger than the first light quantity. When a quantity of the light received by the medium detector exceeds a threshold, the controller determines whether the media overlaps each other, based on the detection result of the multi-feed detector. When the quantity of the light received does not exceed the threshold, the controller skips the determination of whether the media overlaps each other.

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 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.