Finisher and image forming apparatus equipped therewith

A finisher for finishing a booklet having a bundle of center-folded sheets, comprising:

• (a) a detector for detecting an end on a side of a folded portion of the booklet;
• (b) a moving device, which has a pressing member interposing the booklet, for conveying the booklet by movement thereof;
• (c) a controller for controlling the moving device;
• and
• (d) a cutting device for cutting an edge on a side opposite to the end of the booklet, which has been conveyed by the moving device to a cutting position,
• wherein the controller controls the moving device so that the moving device moves in a direction of cutting position from a reference position to a temporary stop position that the detector detects the end on a side of the folded portion of the booklet, after that, the moving device interposes the booklet by the pressing member and moves again in the same direction with the interposing booklet up to a predetermined position which is constant for each sheet size, and
• wherein a sum of movement distance from the reference position to the predetermined position is constant for each sheet size, a movement distance from the reference position to the temporary stop position varies according to the number of sheets constituting the booklet, and a movement distance from the temporary stop position to the predetermined position varies according to the temporary stop position.