Apparatuses and methods for printing security documents

Abstract

A digital printing press for printing security documents is provided. The digital printing press comprises: a first digital print head, the first digital printhead comprising a first array of print nozzles having a first nozzle diameter; a second digital print head, the second digital print head comprising a second array of print nozzles having a second nozzle diameter different from the first nozzle diameter; optionally, an offset printing unit, the offset printing unit comprising one or more offset printing surfaces, wherein the offset printing unit is adapted to transport a print area of the one or more offset printing surfaces sequentially past each of the first and second digital print heads, and subsequently to transfer print received from the first and second digital print heads to a security document substrate; a transport system adapted to transport a security document substrate along a transport path through the digital printing press, wherein either the transport path takes the security document sequentially past each of the first and second digital print heads in a feed direction, or the transport path takes the security document substrate past the offset printing unit, if provided, in a feed direction; a controller adapted to control both the first and second digital print heads to execute a set of printing instructions so as to print on a security document substrate transported past the first and second digital print heads by the transport system or to print on the print area of the one or more offset printing surfaces transported past the first and second digital print heads by the offset printing unit (and to transfer the print received on the print area of the offset printing to the security document substrate), the set of printing instructions including printing instructions at a first resolution for the first digital print head for printing a first print working and printing instructions at a second resolution different from the first resolution for the second digital print head for printing a second print working; wherein the first digital print head is configured to print at the first resolution and the second digital print head is configured to print at the second resolution, and wherein the first and second digital print heads are configured or controlled by the controller to remain static relative to the transport path or offset printing unit while the first and second digital print heads execute the respective printing instructions.