A sheet feeding device includes: a sheet stacking unit that stacks a bundle of sheets; a pick-up roller that is enabled to move up and down and sends a sheet of the bundle of sheets toward downstream side in a carrying direction; a pair of rollers that is arranged at downstream side in the carrying direction, and when multiple sheets are sent out by the pick-up roller, that separates the first sheet from the second sheet or later; a separation member that is arranged between the pick-up roller and the pair of rollers and that is in contact with a leading end of the sheet and limits the number of the sheet carried to the pair of rollers; and a hardware processor that determines a height position of the pick-up roller corresponding to a type of the sheet and sets the pick-up roller to be at the determined height position.

An image reading device includes: a transport unit configured to transport a medium; an emission unit configured to emit an ultrasonic wave in accordance with a driving voltage and a reception unit configured to receive the ultrasonic wave, the emission unit and the reception unit being disposed so that a transport path for the medium transported by the transport unit is interposed therebetween; a reading unit configured to read the medium; and a control unit configured to detect presence or absence of multi-feed of the medium on the basis of a signal received by the reception unit. The image reading device is configured to switch a posture into any of a first posture or a second posture. The first posture is a posture in which the transport path is sloped relative to a mounting surface. The second posture is a posture in which an angle of the transport path relative to the mounting surface is smaller than that in the first posture. The control unit sets a first driving voltage as the driving voltage when the posture is the first posture, and sets a second driving voltage lower than the first driving voltage as the driving voltage when the posture is the second posture.

An image reading device includes: a transport unit configured to transport a medium; an emission unit configured to emit an ultrasonic wave in accordance with a driving voltage and a reception unit configured to receive the ultrasonic wave, the emission unit and the reception unit being disposed so that a transport path for the medium transported by the transport unit is interposed therebetween; a reading unit configured to read the medium; and a control unit configured to detect presence or absence of multi-feed of the medium on the basis of a signal received by the reception unit. The image reading device is configured to switch a posture into any of a first posture or a second posture. The first posture is a posture in which the transport path is sloped relative to a mounting surface. The second posture is a posture in which an angle of the transport path relative to the mounting surface is smaller than that in the first posture. The control unit sets a first driving voltage as the driving voltage when the posture is the first posture, and sets a second driving voltage lower than the first driving voltage as the driving voltage when the posture is the second posture.

A sheet thickness detector incorporated in a sheet conveyor and/or an image forming apparatus includes multiple first rollers aligned in a direction perpendicular to a sheet conveying direction, multiple second rollers facing the respective first rollers, a first roller shaft supporting two first rollers, at least one second roller shaft supporting rollers other than the two first rollers, at least one third roller shaft to support at least three second rollers, a first roller shaft holder supporting the first roller shaft to move from the at least one third roller shaft in a contact/separation direction, a biasing member biasing the first roller shaft toward at least one third roller shaft, and a displacement amount detector detecting an amount of displacement of the first roller shaft. A thickness of a sheet between the first and second rollers is detected based on a detection result by the displacement amount detector.

A sheet thickness detector incorporated in a sheet conveyor and/or an image forming apparatus includes multiple first rollers aligned in a direction perpendicular to a sheet conveying direction, multiple second rollers facing the respective first rollers, a first roller shaft supporting two first rollers, at least one second roller shaft supporting rollers other than the two first rollers, at least one third roller shaft to support at least three second rollers, a first roller shaft holder supporting the first roller shaft to move from the at least one third roller shaft in a contact/separation direction, a biasing member biasing the first roller shaft toward at least one third roller shaft, and a displacement amount detector detecting an amount of displacement of the first roller shaft. A thickness of a sheet between the first and second rollers is detected based on a detection result by the displacement amount detector.

A media conveyance apparatus includes a first conveyer configured to convey media along a conveyance path, a first detector configured to detect overlap-feed of the media conveyed by the first conveyor; and a controller programmed to control operation of the first conveyor based on a detection value from the first detector, a first threshold for detection of single-feed of the media, and a second threshold for detection of overlap-feed of the media.

In a saddle-stitching apparatus, when a sheet is transported to a center-folding unit, a folding blade moves from a retrieved position to a nip position between a pair of folding rollers. A forward end of the folding blade comes into contact with a fold of the sheet, so that the sheet is folded along the fold. When the sheet is attached to the nip position between the folding rollers, the folding rollers start rotating and then, the folding blade inserts the center-folded sheet between the folding rollers. After the center-fold finishing is completed, the rotations of the folding rollers stop in timing at which the folding blade is pulled out of the nip position between the folding rollers. When pulling the folding blade out of the nip position between the folding rollers, the rotations of the folding rollers restart.

In a saddle-stitching apparatus, when a sheet is transported to a center-folding unit, a folding blade moves from a retrieved position to a nip position between a pair of folding rollers. A forward end of the folding blade comes into contact with a fold of the sheet, so that the sheet is folded along the fold. When the sheet is attached to the nip position between the folding rollers, the folding rollers start rotating and then, the folding blade inserts the center-folded sheet between the folding rollers. After the center-fold finishing is completed, the rotations of the folding rollers stop in timing at which the folding blade is pulled out of the nip position between the folding rollers. When pulling the folding blade out of the nip position between the folding rollers, the rotations of the folding rollers restart.

A sheet processing apparatus that can suppress a reduction in a quality of a finish of a fold part of a stack of center-folded sheets without losing an ease of center-folding. The sheet processing apparatus comprises a creasing unit for forming a folding stripe on a sheet so as to facilitate folding the sheet, and an acquisition unit for acquiring information related to a thickness of the sheet. One or more sheets to be provided with folding stripes are determined, from among a plurality of sheets to be folded, according to the information related to the thickness of the sheets, and each of the determined one or more sheets are provided with a folding stripe.

A sheet processing apparatus that can suppress a reduction in a quality of a finish of a fold part of a stack of center-folded sheets without losing an ease of center-folding. The sheet processing apparatus comprises a creasing unit for forming a folding stripe on a sheet so as to facilitate folding the sheet, and an acquisition unit for acquiring information related to a thickness of the sheet. One or more sheets to be provided with folding stripes are determined, from among a plurality of sheets to be folded, according to the information related to the thickness of the sheets, and each of the determined one or more sheets are provided with a folding stripe.