A media alignment calibration system determines a slope relating a trailing edge skew value to its paired leading edge skew value and an intercept representing native skew based on a linear regression of a predetermined number of a set of paired leading and trailing edge skew values for a media type stored in a buffer. Based on the slope and intercept, a media model for the media type is updated based on the linear regression to adjust a differential velocity of a pair of aligned media feed rollers in a media feed mechanism to correct both a future native skew and future paired leading and trailing edge skew values in the buffer to within a desired operational window.

A printing apparatus comprises a conveyance control unit which controls conveyance of printing sheets so that a trailing edge of a preceding sheet as a printing sheet precedingly fed from the stacking unit and a leading edge of a succeeding sheet as a printing sheet succeedingly fed from the stacking unit overlap each other; and a skew correction unit which performs skew correction of the succeeding sheet while the succeeding sheet overlaps the preceding sheet by the conveyance control unit. The skew correction unit makes the leading edge of the succeeding sheet abut against the conveyance roller during a time from an end of a last line feed operation by the conveyance roller for printing on the preceding sheet by the printing unit to start of a next conveyance operation.

A printing apparatus comprises a conveyance control unit which controls conveyance of printing sheets so that a trailing edge of a preceding sheet as a printing sheet precedingly fed from the stacking unit and a leading edge of a succeeding sheet as a printing sheet succeedingly fed from the stacking unit overlap each other; and a skew correction unit which performs skew correction of the succeeding sheet while the succeeding sheet overlaps the preceding sheet by the conveyance control unit. The skew correction unit makes the leading edge of the succeeding sheet abut against the conveyance roller during a time from an end of a last line feed operation by the conveyance roller for printing on the preceding sheet by the printing unit to start of a next conveyance operation.

An image forming apparatus includes a main body, a feeder, and a relay device. The main body forms an image on a sheet. The feeder feeds the sheet toward the main body. The relay device connects the main body to the feeder. The main body is placed on a placement surface. The feeder is arranged opposite to the main body with the relay device therebetween in a direction along the placement surface. The relay device includes a conveyance unit and a casing which houses the conveyance unit. The conveyance unit conveys the sheet fed from the feeder to the main body and rotates relative to the casing with an axis as a pivot thereof. The axis extends in a cross direction intersecting with the placement surface.

An image forming apparatus includes a main body, a feeder, and a relay device. The main body forms an image on a sheet. The feeder feeds the sheet toward the main body. The relay device connects the main body to the feeder. The main body is placed on a placement surface. The feeder is arranged opposite to the main body with the relay device therebetween in a direction along the placement surface. The relay device includes a conveyance unit and a casing which houses the conveyance unit. The conveyance unit conveys the sheet fed from the feeder to the main body and rotates relative to the casing with an axis as a pivot thereof. The axis extends in a cross direction intersecting with the placement surface.

A medium conveying apparatus includes a plurality of feed rollers, each feed roller rotating independently at a respective speed to feed a medium, a first sensor located on a downstream side of the plurality of feed rollers in a medium conveying direction and also in a central part in a direction perpendicular to the medium conveying direction, to detect the medium, a second sensor and a third sensor located on both sides of the first sensor in the direction perpendicular to the medium conveying direction, to respectively detect the medium, and a processor to change the speed of one of the plurality of feed rollers at least until the first sensor detects the medium when any of the second sensor or the third sensor detects the medium and the first sensor does not detect the medium within a predetermined time.

A medium conveying apparatus includes a plurality of feed rollers, each feed roller rotating independently at a respective speed to feed a medium, a first sensor located on a downstream side of the plurality of feed rollers in a medium conveying direction and also in a central part in a direction perpendicular to the medium conveying direction, to detect the medium, a second sensor and a third sensor located on both sides of the first sensor in the direction perpendicular to the medium conveying direction, to respectively detect the medium, and a processor to change the speed of one of the plurality of feed rollers at least until the first sensor detects the medium when any of the second sensor or the third sensor detects the medium and the first sensor does not detect the medium within a predetermined time.

A sheet conveying device, which is included in an image forming apparatus, includes a pair of rollers configured to convey a sheet in a sheet conveyance passage, a detector configured to optically detect an attitude of the sheet, one of a rotation device to rotate the pair of rollers in a direction parallel to a plane of the sheet and a moving device to move the pair of rollers in a width direction, and a controller configured to correct the attitude of the pair of rollers at a time interval, based on a detection result obtained by the detector. The controller performs the correcting operation by setting, according to reflectance of the sheet, at least one of a light emission time of the detector, the time interval of the correcting operation, light emission intensity of the detector and a conveying speed of the sheet.

A sheet conveying device, which is included in an image forming apparatus, includes a pair of rollers configured to convey a sheet in a sheet conveyance passage, a detector configured to optically detect an attitude of the sheet, one of a rotation device to rotate the pair of rollers in a direction parallel to a plane of the sheet and a moving device to move the pair of rollers in a width direction, and a controller configured to correct the attitude of the pair of rollers at a time interval, based on a detection result obtained by the detector. The controller performs the correcting operation by setting, according to reflectance of the sheet, at least one of a light emission time of the detector, the time interval of the correcting operation, light emission intensity of the detector and a conveying speed of the sheet.

A medium conveying apparatus includes a plurality of feed rollers, each feed roller rotating independently at a respective speed to feed a medium, a first sensor located on a downstream side of the plurality of feed rollers in a medium conveying direction and also in a central part in a direction perpendicular to the medium conveying direction, to detect the medium, a second sensor and a third sensor located on both sides of the first sensor in the direction perpendicular to the medium conveying direction, to respectively detect the medium, and a processor to change the speed of one of the plurality of feed rollers at least until the first sensor detects the medium when any of the second sensor or the third sensor detects the medium and the first sensor does not detect the medium within a predetermined time.