US Patent 9004640 Printing apparatus

A printing apparatus, in which a time required for printing is shortened, includes a first printing unit that performs printing on a first surface of a sheet by an ink jet system, and a second printing unit that performs printing on a second surface of the sheet by the ink jet system, the second printing unit being disposed on a downstream side of the first printing unit. Moreover, the printing apparatus includes a sheet discharge sensor that detects the sheet to be discharged from the second printing unit. The sheet discharge sensor includes an arm having a rotating member supported thereon, the rotating member being brought into contact with the sheet being conveyed while being rotated.