According to some examples, a skew detection device comprises a first roller rotatable around a first axis, a second roller rotatable around a second axis, a first sensor, and a second sensor. The first sensor measures a first rotation parameter from the first roller and the second sensor measures a second rotation parameter from the second roller. A movement of a print media over the device rotates the first contact roller and the second roller, and a controller determines a skew of the print media based on the first and second rotation parameters captured by the first sensor and the second sensor.

A sheet conveyance apparatus includes a sheet supporting tray to support a sheet, a sheet conveyance unit to convey the sheet supported on the sheet supporting tray, a first detection sensor to detect the supported sheet at a first detection position, and a second detection sensor to detect the supported sheet at a second detection position farther from a center of the sheet supporting tray in a sheet width direction than the first detection position. In addition, a control unit controls the sheet conveyance unit in a first mode in a case where the first and second detection sensors detect the sheet, and controls the sheet conveyance unit in a second mode in which a sheet conveyance speed is slower than that of the first mode in a case where the first detection sensor detects the sheet and the second detection sensor detects no sheet.

A sheet conveyance apparatus includes a sheet supporting tray to support a sheet, a sheet conveyance unit to convey the sheet supported on the sheet supporting tray, a first detection sensor to detect the supported sheet at a first detection position, and a second detection sensor to detect the supported sheet at a second detection position farther from a center of the sheet supporting tray in a sheet width direction than the first detection position. In addition, a control unit controls the sheet conveyance unit in a first mode in a case where the first and second detection sensors detect the sheet, and controls the sheet conveyance unit in a second mode in which a sheet conveyance speed is slower than that of the first mode in a case where the first detection sensor detects the sheet and the second detection sensor detects no sheet.

A stacker module includes a lift table, a stacker configured to place sheets that are successively supplied thereto onto the top of a stack forming on the lift table, a controller configured to lower the lift table as the stack grows, a height-adjustable eject table, and an eject mechanism configured to transfer a completed stack from the lift table onto the eject table. The eject mechanism is height-adjustable for transferring stacks onto the eject table in different height positions of the lift table.

A stacker module includes a lift table, a stacker configured to place sheets that are successively supplied thereto onto the top of a stack forming on the lift table, a controller configured to lower the lift table as the stack grows, a height-adjustable eject table, and an eject mechanism configured to transfer a completed stack from the lift table onto the eject table. The eject mechanism is height-adjustable for transferring stacks onto the eject table in different height positions of the lift table.

An image forming apparatus includes a paper discharging tray and a paper detection part disposed at an upstream end of the paper discharging tray in a paper discharge direction. The paper detection part includes a base end member provided rotatably around a first axis extending in a direction perpendicular to a paper discharge direction and a tip member pivoted to the base end member to rotate around a second axis parallel to the first axis, and extending downwardly to incline toward an upstream side of the paper discharge direction in a state where the base end member is not subjected to pressure from the paper being discharged. The base end member is disposed to face a discharge opening when being at the reference position, and the image forming apparatus stops discharging paper from the discharge opening when the base end member rotates by a predetermined threshold or more with respect to the reference position.

An image forming apparatus includes a paper discharging tray and a paper detection part disposed at an upstream end of the paper discharging tray in a paper discharge direction. The paper detection part includes a base end member provided rotatably around a first axis extending in a direction perpendicular to a paper discharge direction and a tip member pivoted to the base end member to rotate around a second axis parallel to the first axis, and extending downwardly to incline toward an upstream side of the paper discharge direction in a state where the base end member is not subjected to pressure from the paper being discharged. The base end member is disposed to face a discharge opening when being at the reference position, and the image forming apparatus stops discharging paper from the discharge opening when the base end member rotates by a predetermined threshold or more with respect to the reference position.

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.

Provided is a document conveying apparatus that properly discharges documents regardless of the amount of documents stacked on a discharge tray without complicated construction of a transmission mechanism for transmitting a driving force to conveying rollers. A conveying roller pair is provided at an end portion on an upstream side. A swing mechanism swings a discharge mechanism centered around a drive shaft of the conveying roller pair. An upper surface height measuring unit measures the height of the upper surface of documents stacked on the discharge tray. A control unit, by causing the swing mechanism to swing the discharge mechanism according to the height measured by the upper surface height measuring unit, performs control so that the difference between a discharge port and the upper surface of the documents stacked on the discharge tray is within a specified range.