US Patent 7924455 Simultaneous duplex digital printer

A duplex printer includes a pair of print engines, each print engine comprising at least one printhead and one transfer roller for receiving ink ejected from the at least one printhead; a pair of print media trays provided upstream and downstream of the pair of print engines, each print media tray comprising a movable platen for supporting a stack of print media and a motorized mechanism for moving the platen; and a print media feed arrangement for feeding print media from one of the pair of print media trays to the other of the pair of print media trays along a print media feed path. The transfer rollers of the pair of print engines are provided opposite each other with respect to the print media feed path.