Image forming apparatus, sheet conveying method, and program for sheet conveyance

A sheet conveying method in an image forming apparatus which turns back a sheet from a first conveying direction toward the outside of the apparatus to a second conveying direction toward the inside of a reversal conveyance path to reverse a front side and a back side of the sheet, the apparatus including an intermediate conveyance unit, an outer conveyance unit, and a roller, the intermediate conveyance unit being positioned upstream from the reversal conveyance path in the second conveying direction and midway in a sheet conveyance path on which the sheet is conveyed during the conveyance involving the turning back, the outer conveyance unit being positioned adjacent to the intermediate conveyance unit upstream from the intermediate conveyance unit in the second conveying direction, the intermediate conveyance unit being configured to be pulled out of the apparatus together with a portion of the sheet conveyance path, and the roller conveying the sheet within the sheet conveyance path in the second conveying direction, the method comprising:

• determining whether or not the sheet to be turned back is long enough in a sheet conveying direction so as to extend into the other conveyance unit during the conveyance of the sheet involving the turning back;
• controlling a roller such that the sheet to be turned back and directed into the reversal conveyance path is caused to wait until the sheet can be conveyed into the reversal conveyance path;
• setting, as a standby position of the sheet while the sheet is caused to wait, a position such that an upstream end portion in the second conveying direction of the sheet to be directed into the reversal conveyance path does not extend for a predetermined length or longer into the outer conveyance unit adjacent to the intermediate conveyance unit upstream from the intermediate conveyance unit in the second conveying direction;
• and
• causing the sheet to wait at the standby position only if it is determined that the sheet is long enough so as to extend into the outer conveyance unit during the conveyance involving the turning back.