A sheet processing device includes a first conveyance passage, a first conveyor, a second conveyor, a folder, a second conveyance passage, and circuitry. The circuitry is configured to (1) cause the first conveyor and the second conveyor to convey the sheet nipping the sheet to warp the sheet between the first conveyor and the second conveyor, (2) guide the warped sheet to form a first fold on the sheet by the folder and circulate the sheet to the first conveyance passage, (3) cause the first conveyor and the second conveyor to convey the sheet while nipping the sheet again to warp the sheet between the first conveyor and the second conveyor, (4) guide the warped sheet to form a second fold on the sheet by the folder, and (5) cause the second conveyor to convey the sheet with the first fold and the second fold.

A sheet processing device includes a first conveyance passage, a first conveyor, a second conveyor, a folder, a second conveyance passage, and circuitry. The circuitry is configured to (1) cause the first conveyor and the second conveyor to convey the sheet nipping the sheet to warp the sheet between the first conveyor and the second conveyor, (2) guide the warped sheet to form a first fold on the sheet by the folder and circulate the sheet to the first conveyance passage, (3) cause the first conveyor and the second conveyor to convey the sheet while nipping the sheet again to warp the sheet between the first conveyor and the second conveyor, (4) guide the warped sheet to form a second fold on the sheet by the folder, and (5) cause the second conveyor to convey the sheet with the first fold and the second fold.

A post-processing apparatus includes memory and a processor configured to control a curving device that curves a sheet, which is transported to the curving device, by pressing the sheet, control folding processing that is performed on a sheet curved by the curving device, and control, when folding processing is performed such that two ends of a sheet in a transport direction of the sheet face outward in opposite directions after the folding processing has been performed on the sheet, the curving device so as to curve the sheet in plural directions with respect to a transport surface.

A post-processing apparatus includes memory and a processor configured to control a curving device that curves a sheet, which is transported to the curving device, by pressing the sheet, control folding processing that is performed on a sheet curved by the curving device, and control, when folding processing is performed such that two ends of a sheet in a transport direction of the sheet face outward in opposite directions after the folding processing has been performed on the sheet, the curving device so as to curve the sheet in plural directions with respect to a transport surface.

A sheet supplying unit 1 supplies sheets S one by one. A knife-type folding unit 5 folds the sheet. A first sensor 28 detects the sheet entering the folding position. A second sensor 30a, 30b detects the sheet passing through the opening. A timer 31 measures a time interval from end of sheet detection by the second sensor to start of sheet detection by the first sensor. A sheet feed interval change unit 33 calculates a reduction amount of the sheet feed interval using the measured values of the timer and changes the sheet feed interval based on the reduction amount each time a predetermined number of the sheets are folded.

A sheet supplying unit 1 supplies sheets S one by one. A knife-type folding unit 5 folds the sheet. A first sensor 28 detects the sheet entering the folding position. A second sensor 30a, 30b detects the sheet passing through the opening. A timer 31 measures a time interval from end of sheet detection by the second sensor to start of sheet detection by the first sensor. A sheet feed interval change unit 33 calculates a reduction amount of the sheet feed interval using the measured values of the timer and changes the sheet feed interval based on the reduction amount each time a predetermined number of the sheets are folded.

A sheet pressing device includes a carry-in port that receives a Z-folded sheet having two folds; an additional folding roller disposed downstream of the carry-in port to press the fold; a lower folding guide having a pedestal disposed opposite to the additional folding roller; a first moving mechanism that moves the additional folding roller between a pressing position at which the additional folding roller is made to approach the pedestal and a retreat position at which the additional folding roller is moved relative to the pedestal from the pressing position; a second moving mechanism that moves the additional folding roller along the fold; and a control part. The control part controls the second moving mechanism so as to increase the number of times the additional folding roller is moved along the fold when a sheet section is positioned between the additional folding roller and the fold.

A sheet pressing device includes a carry-in port that receives a Z-folded sheet having two folds; an additional folding roller disposed downstream of the carry-in port to press the fold; a lower folding guide having a pedestal disposed opposite to the additional folding roller; a first moving mechanism that moves the additional folding roller between a pressing position at which the additional folding roller is made to approach the pedestal and a retreat position at which the additional folding roller is moved relative to the pedestal from the pressing position; a second moving mechanism that moves the additional folding roller along the fold; and a control part. The control part controls the second moving mechanism so as to increase the number of times the additional folding roller is moved along the fold when a sheet section is positioned between the additional folding roller and the fold.

A printing apparatus includes a printing unit, a post-processing unit, and a controller. The controller includes a paper-type setting section configured to set a paper type of a paper feeding section, a storing section configured to store a plurality of paper types for which specific post processing is possible, and a control executing section. The printing output data includes paper type designation information, paper feeding section designation information, and post-processing designation information. When the post-processing designation information designates selection of the specific post processing and predetermined conditions including a condition that a paper type of second paper set by the paper-type setting section coincides with any one of the plurality of paper types stored in the storing section are satisfied, the control executing section controls the printing unit and the post-processing unit according to the paper feeding section designation information and the post-processing designation information irrespective of designation by the paper type designation information.

A printing apparatus includes a printing unit, a post-processing unit, and a controller. The controller includes a paper-type setting section configured to set a paper type of a paper feeding section, a storing section configured to store a plurality of paper types for which specific post processing is possible, and a control executing section. The printing output data includes paper type designation information, paper feeding section designation information, and post-processing designation information. When the post-processing designation information designates selection of the specific post processing and predetermined conditions including a condition that a paper type of second paper set by the paper-type setting section coincides with any one of the plurality of paper types stored in the storing section are satisfied, the control executing section controls the printing unit and the post-processing unit according to the paper feeding section designation information and the post-processing designation information irrespective of designation by the paper type designation information.