Image forming apparatus

An image forming apparatus, comprising:

• a first container configured to accommodate a medium;
• a second container configured to accommodate a medium;
• an image forming device configured to perform an image forming operation to form an image on an image-formable side of the medium from either one of the first container or the second container;
• a medium conveyer configured to convey the medium, the medium conveyer including:
• a conveyer path, including:
• a common conveyer path extending from the first container through the image forming device to an exit of the image forming apparatus;
• and
• a reverse conveyer path branched off from the common conveyer path at a branch point, extending to a position overlapping the image forming device, and merging with the common conveyer path at a merge point, the reverse conveyer path and a part of the common conveyer path between the merge point and the branch point forming a closed path;
• a first roller located at a position downstream from the branch point in a conveying direction to convey the medium in the conveyer path;
• and
• a second roller located in the reverse conveyer path,
• the medium conveyer being configured to selectively perform:
• a first conveying operation, in which the medium conveyer conveys the medium from the first container to the image forming device with one of a first side and a second side thereof to be used as the image-formable side;
• a second conveying operation, in which, after the image forming operation to the medium conveyed in the first conveying operation, the medium conveyer conveys the medium with the other of the first side and the second side thereof to be used as the image-formable side;
• and
• a third conveying operation, in which the medium conveyer conveys the medium from the second container to the image forming device with one of a first side and a second side thereof to be used as the image-formable side,
• a command acquiring device configured to acquire a user command, the user command indicating at least one of the first side or the second side of the medium accommodated in one of the first container and the second container, on which the image forming operation is to be performed;
• and
• a controller configured to:
• when the user command indicates that the image forming operation is to be performed on both the first side and the second side of the medium accommodated in the first container, conduct one of a first duplex operation and a second duplex operation, the controller being configured to conduct the first duplex operation when a first condition is satisfied but conduct the second duplex operation when a second condition is satisfied, the first condition including a condition that a length of the medium to be conveyed by the medium conveyer is encompassed in a range greater than or equal to a first threshold value and smaller than or equal to a second threshold value, the first threshold value being smaller than the second threshold value, the second condition including a condition that the first condition is not satisfied,
• for the first duplex operation, the controller being configured to control the medium conveyer to perform the first conveying operation and the second conveying operation and control the image forming device to perform the image forming operation on the first side and the second side of the medium from the first container, and
• for the second duplex operation, the controller being configured to control the medium conveyer to perform the first conveying operation and control the image forming device to perform the image forming operation on the one of the first side and the second side of the medium from the first container, and, after the medium is accommodated in the second container in an orientation with the other of the first side and the second side of the medium opposite to the one side having the image formed thereon to be used as the image-formable side, control the medium conveyer to perform the third conveying operation to the medium from the second container and control the image forming device to perform the image forming operation to the medium conveyed from the second container in the third conveying operation,
• wherein the first threshold value corresponds to a length equal to or greater than a distance between the first roller and the second roller along the common conveyer path and the reverse conveyer path, and
• wherein the second threshold value corresponds to a length equal to or smaller than a length of the closed path.