A sheet feeder apparatus is provided. The apparatus comprises 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 a sheet having a first width at a plurality of first positions, a second detector for 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 is provided. The apparatus comprises 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 a sheet having a first width at a plurality of first positions, a second detector for 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.

An image forming apparatus includes a stacking unit, a pickup roller, a conveying roller, a transfer unit, a motor, a determiner, and a velocity adjuster. The conveying roller conveys, in a conveying direction, a sheet fed by the pickup roller from the stacking unit. The determiner determines a value of a parameter corresponding to a load torque applied to a motor rotor. Based on a length between a front end of the sheet and a nip position of the conveying roller at a first timing when the determined value changes from a value smaller than a predetermined value to a value greater than the predetermined value, and a length between the nip position and a predetermined position downstream of the conveying roller and upstream of an image forming position in the conveying direction, the velocity adjuster adjusts a conveying velocity at which the sheet is conveyed to the predetermined position.

A sheet conveying device, which is included in an image forming apparatus, includes a drive device, a pair of sheet holding rollers to convey a sheet in a sheet conveying direction, a gate to which a leading end of the sheet contacts, a first detector disposed upstream from the pair of sheet holding rollers to detect a position of the sheet and a second detector disposed downstream from the pair of sheet holding rollers to detect a position of the sheet. The pair of sheet holding rollers performs a primary correction to detect and correct a lateral displacement amount of the sheet by moving the pair of sheet holding rollers while holding the sheet, and then performs a secondary correction to detect and correct at least one of a subsequent lateral displacement of the sheet and an angular displacement of the sheet.

A sheet conveying device, which is included in an image forming apparatus, includes a drive device, a pair of sheet holding rollers to convey a sheet in a sheet conveying direction, a gate to which a leading end of the sheet contacts, a first detector disposed upstream from the pair of sheet holding rollers to detect a position of the sheet and a second detector disposed downstream from the pair of sheet holding rollers to detect a position of the sheet. The pair of sheet holding rollers performs a primary correction to detect and correct a lateral displacement amount of the sheet by moving the pair of sheet holding rollers while holding the sheet, and then performs a secondary correction to detect and correct at least one of a subsequent lateral displacement of the sheet and an angular displacement of the sheet.

The invention relates to a sheet alignment device (5) for a machine for the processing of sheets (B) consisting of a thin, flat material such as paper, cardboard or film, with a feed section, at least one sensor (30, 32) for determining the position and/or alignment of the sheet (B) and also at least two alignment modules (10), each having an alignment roller (12), to which a drive device (14) is assigned in each case, whereby there is assigned to each alignment module (10) a swivel device (16), with which the alignment roller (10) can be swivelled around a swivel axis (A) perpendicular to the feed section. The invention relates also to a machine for the processing of sheets (B) consisting of a thin, flat material such as paper, cardboard or film, whereby a sheet alignment device (5) of the aforementioned type is provided. The invention relates finally to a method for the aligning of a sheet (B) consisting of thin, flat material such as paper, cardboard or film by means of the following steps: the alignment of the sheet (B) is determined, the sheet (B) is speeded up, turned and/or displaced laterally by means of at least two alignment rollers (12), controllable with regard to circumferential speed and alignment, on a feed section.

The invention relates to a sheet alignment device (5) for a machine for the processing of sheets (B) consisting of a thin, flat material such as paper, cardboard or film, with a feed section, at least one sensor (30, 32) for determining the position and/or alignment of the sheet (B) and also at least two alignment modules (10), each having an alignment roller (12), to which a drive device (14) is assigned in each case, whereby there is assigned to each alignment module (10) a swivel device (16), with which the alignment roller (10) can be swivelled around a swivel axis (A) perpendicular to the feed section. The invention relates also to a machine for the processing of sheets (B) consisting of a thin, flat material such as paper, cardboard or film, whereby a sheet alignment device (5) of the aforementioned type is provided. The invention relates finally to a method for the aligning of a sheet (B) consisting of thin, flat material such as paper, cardboard or film by means of the following steps: the alignment of the sheet (B) is determined, the sheet (B) is speeded up, turned and/or displaced laterally by means of at least two alignment rollers (12), controllable with regard to circumferential speed and alignment, on a feed section.

A sheet conveying device includes a conveying roller pair, a correction unit, and a control unit. The correction unit includes a correction roller pair and a roller holder. The control unit moves the roller holder from a reference position, and returns the roller holder to the reference position after the sheet is nipped by the correction roller pair, and after this sheet correction operation, the control unit releases the nip of the conveying roller pair. At least either a swing speed vh when returning the roller holder to the reference position, or a deflection amount of the sheet before the roller holder is returned to the reference position, is adjusted so that tension is not applied to the sheet between the conveying roller pair and the correction roller pair.

A sheet conveying device includes a conveying roller pair, a correction unit, and a control unit. The correction unit includes a correction roller pair and a roller holder. The control unit moves the roller holder from a reference position, and returns the roller holder to the reference position after the sheet is nipped by the correction roller pair, and after this sheet correction operation, the control unit releases the nip of the conveying roller pair. At least either a swing speed vh when returning the roller holder to the reference position, or a deflection amount of the sheet before the roller holder is returned to the reference position, is adjusted so that tension is not applied to the sheet between the conveying roller pair and the correction roller pair.

A register (20; 60) for a processing machine (1) for processing plate-like elements (10) includes a gripping element (21; 22) for placing the plate-like elements (10) in a gripper bar (31) of a conveyor (30) of a processing machine (1) conveying the plate-like elements (10) in a longitudinal direction, an actuator module (201, 202) to drive the gripping element (21; 22), at least one front correction sensor module (7) configured to measure the front position of register marks (12a) printed on a front section of the plate-like element (10) grasped by the gripping element (21; 22). The register (20; 60) includes at least one front pre-correction sensor module (80), placed upstream of the front correction sensor module (7) in the longitudinal direction, the front pre-correction sensor module (80) is configured: to detect the passage of a front transversel edge of the plate-like element (10) in at least two longitudinally spaced lateral axis of detection (P1, P2), one located in front of the other, and to provide measurements to a computation and control unit (40) of the processing machine (1) that is configured: to control the actuator module (201, 202) in order to move the gripping element (21; 22) toward the gripper bar (31) and to activate the gripping element (21; 22) in order to grasp a plate-like element (10). Also a processing machine for processing plate-like elements includes the register. A method for placing plate-like elements within a processing machine is disclosed.