Patent ID: 8301048

Claim:
Method of controlling a circumferential register in a digital multi-color printing machine for printing sheets during a printing process, in particular in an electrophotographically operating printing machine, comprising: producing for each sheet, at least one register mark per color printing unit of the multi-color printing machine is assigned to said sheet and defined with respect to its position, relative to one of the color marks itself, said color marks being applied to a support for said sheets and downstream of the respectively associated sheet, and, controlling the circumferential register of at least one sheet following the sheet associated with said determined register marks based on the determination of the position of the register marks of the at least one sheet, the circumferential register of the at least one sheet, said sheet following the sheet associated with said determined register marks downstream of the printing process, wherein duplex printing a sheet by recto and verso printing, register marks are applied for each side, that said register marks are assigned to the respective side of the sheet and determined with respect to their position, that, in order to control recto printing of at least one subsequent sheet, the positions of register marks assigned to the recto printing side of a previous sheet are analyzed, and that, in order to control verso printing of at least one subsequent sheet, the positions of register marks assigned to the verso printing side of a previous sheet are analyzed.