A post-processing apparatus includes a post-processing unit configured to receive sheets from an image forming apparatus, perform processing on the received sheets, and then discharge the processed sheets through a discharge port. A sensor is configured to detect a presence of an object at the discharge port. The sensor includes a first light emitter on a first side of the discharge port that is positioned to emit a light across a width of the discharge port, a reflector on a second side of the discharge port opposite the first side in a first direction, and a first light receiver positioned to receive light of the first light emitter from the reflector. A controller is configured to terminate the processing on the received sheets by the post-processing unit when the sensor detects the presence of the object at the discharge port.

A post-processing apparatus includes a post-processing unit configured to receive sheets from an image forming apparatus, perform processing on the received sheets, and then discharge the processed sheets through a discharge port. A sensor is configured to detect a presence of an object at the discharge port. The sensor includes a first light emitter on a first side of the discharge port that is positioned to emit a light across a width of the discharge port, a reflector on a second side of the discharge port opposite the first side in a first direction, and a first light receiver positioned to receive light of the first light emitter from the reflector. A controller is configured to terminate the processing on the received sheets by the post-processing unit when the sensor detects the presence of the object at the discharge port.

A medium feeding apparatus includes a medium mounting section forming a mounting face for mounting a medium thereon, a feeding roller configured to feed a lowermost medium among mediums mounted on the medium mounting section in a feeding direction, and a movement detection unit configured to output information related to movement of the medium in a direction along the mounting face, wherein based on detection information detected by a medium height detection unit that outputs information related to a height of the medium mounted on the mounting section from the mounting face in abnormality detection processing, when the height is less than a first threshold value, a control unit continues feeding the medium regardless of detection information detected by the movement detection unit or without obtaining detection information detected by the movement detection unit.

A control unit of a medium feeding apparatus is configured to execute a fault detection process to determine that there is a feeding fault when a movement of a subsequent medium in a feeding direction is detected based on detection information of a movement detection unit within a fault detection period that is set after a trailing edge of a preceding medium is detected based on the detection information of the movement detection unit and before feeding of the subsequent medium is started, and the fault detection period set when a size of the medium in a width direction intersecting the feeding direction is a first size is shorter than the fault detection period set when the size of the medium in the width direction is a second size larger than the first size.

A sheet feeding apparatus includes a first detection device that outputs a first signal upon detecting a stacked sheet and outputs a second signal upon detecting no sheet, and a second detection device that outputs a third signal when a sheet stacking member is above a predetermined position and outputs a fourth signal in a case where the stacking member is below the predetermined position A control unit controls movement of sheet stacking member by restricting movement of the stacking member when the second signal is output and the third signal is output when power of the sheet feeding apparatus is turned on. The second detection device includes a switch that emits the third signal while abutting a moving member that moves with the sheet stacking member and emits the fourth signal while being separated from the moving member.

A sheet feeder apparatus includes a width detector for a sheet placed on a sheet placement portion, a conveyor for conveying sheets while separating the sheets one by one, a first detector for detecting a sheet having a first width at a plurality of first positions, a second detector for detecting a sheet having a second width that is not detected by the first sheet detector at a plurality of second positions, and a controller for determining skewing of a sheet based on a result of the detection of the sheet performed by the first detector if the width of the sheet is the first width, and determining skewing of a sheet based on a result of the detection performed by the second detector if the width of the sheet is the second width.

A sheet feeder apparatus includes a width detector for a sheet placed on a sheet placement portion, a conveyor for conveying sheets while separating the sheets one by one, a first detector for detecting a sheet having a first width at a plurality of first positions, a second detector for detecting a sheet having a second width that is not detected by the first sheet detector at a plurality of second positions, and a controller for determining skewing of a sheet based on a result of the detection of the sheet performed by the first detector if the width of the sheet is the first width, and determining skewing of a sheet based on a result of the detection performed by the second detector if the width of the sheet is the second width.

A post-processing apparatus according to an embodiment includes a processing tray, a post-processing section, a sensor, and a control section. A sheet supplied from an image forming apparatus is led into the processing tray through a lead-in path. The post-processing section applies post-processing to the sheet sent from the processing tray. The sensor detects an object passing a detection space in the lead-in path. The control section controls operation of the post-processing section based on a time in which the sensor detects the object.

A post-processing apparatus according to an embodiment includes a processing tray, a post-processing section, a sensor, and a control section. A sheet supplied from an image forming apparatus is led into the processing tray through a lead-in path. The post-processing section applies post-processing to the sheet sent from the processing tray. The sensor detects an object passing a detection space in the lead-in path. The control section controls operation of the post-processing section based on a time in which the sensor detects the object.

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.