Patent ID: 7967290

Claim:
An image forming apparatus comprising: a main body frame; a sheet feeding section that is provided in the main body frame and feeds a sheet one by one; an image forming section that is provided in the main body frame and transfers a specified image to the sheet fed from the sheet feeding section; a fixing section that is provided in the main body frame and fixes the image transferred to the sheet by the image forming section; a relay unit that is provided in the main body frame to be capable of being pulled out, and includes a conveyance switching mechanism to eject the sheet on which the image is fixed by the fixing section to a specified sheet ejection section or to switch back the sheet without ejecting; an intermediate unit that is, together with the fixing section, fixed and placed in the main body frame, and guides the sheet switched back by the relay unit toward a specified direction; an automatic duplex unit that is mounted to the main body frame to be capable of being detached therefrom, and guides the switched back sheet guided by the intermediate unit to the image forming section, wherein the automatic duplex unit is supported to be capable of performing parallel movement toward outside of the main body frame by a guide arm provided between the automatic duplex unit and the main body frame, and the automatic duplex unit can be attached to and detached from the main body frame by the parallel movement; a guide member that is provided in the intermediate unit, is constructed to be capable of being opened and closed between a specified guide position at which the switched back sheet is guided to the automatic duplex unit and an open position opposite to the guide position, and receives a spring force toward the open position; and an opening and closing mechanism that is provided in the intermediate unit that moves the guide member to the guide position by contact with a pressing body of an automatic duplex unit side when the automatic duplex unit is mounted to the main body frame, and opens the guide member to the open position by the spring force when the automatic duplex unit is detached from the main body frame.