Patent ID: 7871066

Claim:
A sheet post-processing unit, comprising: a sheet stacking portion which stacks each sheet sequentially discharged one after another; a sheet conveying portion which conveys each sheet to stacked on said sheet stacking portion; an intersectional moving device which moves said sheet conveying portion in a direction intersecting with a sheet discharging direction; a vertical moving device which moves up and down said sheet conveying portion in a vertical direction; an intersectional regulating member which aligns each sheet by contacting an edge of each sheet to a side in a direction intersecting with the sheet discharging direction; and a controller which controls said intersectional moving device and said vertical moving device, wherein said controller is configured to control: (i) movement of said sheet conveying portion by said vertical moving device from a separated position, where said sheet conveying portion is separated from the sheet and is distant from said intersectional regulating member, to a press-contact position, where said sheet conveying portion press-contacts an upper surface of the sheet, (ii) movement of said sheet conveying portion by said intersectional moving device in the direction of said intersectional regulating member from the press-contact position while press-contacting the upper surface of the sheet by said sheet conveying portion, (iii) separation of said sheet conveying portion from the sheet by said vertical moving device, and (iv) movement of said sheet conveying portion, separated from the sheet, by said intersectional moving device in a direction of the separated position and which intersects with the sheet discharging direction.