Image forming apparatus capable of forming images in double-sided mode

摘要

An image forming apparatus which enables double-sided image formation using a sheet feeding unit, and is capable of discharging a sheet, whose sheet length is undetermined by the time the sheet reaches a branch area in conveyance for double-sided image formation, without guiding it to a sheet inverting unit. A conveying flapper switches a destination for a sheet to a first conveying path leading to a sheet inverting unit or a second conveying path leading to a sheet discharge tray. A length of a sheet in a conveying direction is detected while the sheet is being conveyed. When a size of the sheet is undetermined, and the length of the sheet is not detected by the time the sheet reaches the conveying flapper, the conveying flapper is controlled so as to convey the sheet with an image formed on a first side thereof to the second conveying path.

主权项

1. An image forming apparatus capable of executing a double-sided mode in which images are formed on both sides of a sheet, comprising:
a sheet feeding unit configured to feed a sheet; an image forming unit configured to form images on the sheet fed from said sheet feeding unit; a sheet inverting unit configured to invert the sheet, on which an image has been formed on a first side thereof by said image forming unit, in the double-sided mode; a sheet discharge tray onto which the sheet on which the mage has been formed by said image forming unit is discharged; a switching unit configured to switch a conveyance destination for the sheet to a first conveying path leading toward said sheet inverting unit or a second conveying path leading to said sheet discharge tray; a detection unit configured to detect a length of the sheet, which is fed from said sheet feeding unit, in a conveying direction while the sheet is being conveyed; and a control unit configured to, when a size of the sheet has not been undetermined and the length of the sheet in the conveying direction is not detected by said detection unit by the time the sheet reaches said switching unit in the double-sided mode, control said switching unit so that the sheet with the image formed on the first side thereof can be conveyed to the second conveying path, wherein said control unit controls said switching unit so that the sheet is conveyed to the first conveying path when the length of the sheet in the conveying direction detected by said detection unit lies inside a predetermined range, and the sheet is conveyed to the second conveying path when the length of the sheet in the conveying direction detected by said detection unit falls outside the predetermined range.