Sheet post-processing device

1. A sheet post-processing device, comprising:

a discharge port having a pair of discharge rollers that discharge a sheet including a folded sheet subjected to folding processing;

a discharge tray on which the sheet discharged through the discharge port is stacked;

a first sheet holding member that is attached above the pair of discharge rollers and that holds the folded sheet stacked on the discharge tray by an upstream part of the folded sheet in a discharge direction of the folded sheet; and

a second sheet holding member that is attached above the pair of discharge rollers and that holds the folded sheet stacked on the discharge tray by a downstream part of the folded sheet in the discharge direction of the folded sheet,

wherein

the first sheet holding member and the second sheet holding member are, on a downstream side of the pair of discharge rollers in the discharge direction of the folded sheet, selectively disposed

at a holding position, at which the first sheet holding member and the second sheet holding member intersect a discharge route for the folded sheet and extend downward from above the pair of discharge rollers toward the discharge tray to hold the folded sheet, and

at a retreat position retreated to above the discharge route for the folded sheet, the sheet post-processing device further comprising:

a driving portion that shifts the first sheet holding member and the second sheet holding member to the holding position and the retreat position; and

a control portion that controls operation of the pair of discharge rollers and the driving portion,

wherein

the control portion

disposes the first sheet holding member and the second sheet holding member at the holding position in a case where the folded sheet is discharged through the discharge port, and

disposes the first sheet holding member and the second sheet holding member at the retreat position in a case where the sheet not subjected to the folding processing is discharged through the discharge port.

2. The sheet post-processing device according to claim 1 ,

wherein

the first sheet holding member and the second sheet holding member are attached above the pair of discharge rollers so as to be swingable about a rotation shaft extending in a sheet width direction orthogonal to the discharge direction of the folded sheet,

an angle detection portion is provided which detects an angle of swing of the first sheet holding member and the second sheet holding member, and

the control portion, based on an angle of the first sheet holding member and the second sheet holding member detected by the angle detection portion, disposes the first sheet holding member and the second sheet holding member at the holding position or the retreat position.

3. The sheet post-processing device according to claim 1 ,

wherein

one of the first sheet holding member and the second sheet holding member is connected to the driving portion and is caused by the driving portion to reciprocate between the holding position and the retreat position, and

an other of the first sheet holding member and the second sheet holding member is in engagement with, and moves following, the one of the first sheet holding member and the second sheet holding member, thereby to reciprocate between the holding position and the retreat position.

4. The sheet post-processing device according to claim 1 ,

wherein

the second sheet holding member makes contact with the folded sheet on each of opposite sides of the folded sheet in a sheet width direction orthogonal to the discharge direction of the folded sheet, and

the first sheet holding member makes contact with the folded sheet at a position that is inward, in the sheet width direction, of contact portions of the second sheet holding member which make contact with the folded sheet on each of the opposite sides of the folded sheet in the sheet width direction.