Patent ID: 8528477

Claim:
A sheet inspection system for a sheet-fed recto-verso printing press of the type including first and second blanket cylinders for carrying out simultaneous recto-verso printing of the sheets, the sheet inspection system comprising: a first inspection device for taking an image of a first side of the printed sheets, wherein the first and second blanket cylinders are sitting one next to the other along a same horizontal plane, wherein the first inspection device includes a first line image sensor for performing line-scanning image acquisition of the first side of the printed sheets, wherein the first inspection device is disposed in such a way that the first line image sensor visually acquires an image of the first side of a printed sheet that has been freshly printed at a printing nip between the first and second blanket cylinders, before drying of the printed sheet, while a second side of the printed sheet is still adhering onto the surface of the first blanket cylinder of the printing press, thanks to a sticking effect of fresh ink applied by the first blanket cylinder on the second side of the printed sheet, and immediately before the printed sheet is transferred to a chain gripper system of the printing press, which chain gripper system extends below the first and second blanket cylinders, and wherein the first inspection device further comprises a mirror for diverting the optical path of the first line image sensor onto the surface of the first blanket cylinder, the first line image sensor and mirror being disposed below the second blanket cylinder.