Fault tolerance in high volume printing presses

A method of restoring operation in a modular digital color printing press prior to the correction of the fault causing operation of one module to fail said method including the steps:

• (a) providing at least one additional spare printing module to the number of printing modules required for the printing task in the absence of a fault, said spare printing module being the most downstream of the printing modules for which faults are to be compensated;
• (b) transferring data representing the page or sheet to be printed to a downstream printing module after detection of a fault in a faulty printing module;
• and
• (c) transferring data in said downstream printing module to the printing module downstream of said downstream printing module prior to or substantially simultaneously with the transfer of data into said downstream printing module from said faulty printing module.

In a digital printing system comprising (i) a plurality of printing modules serially arranged along a print output transport path, (ii) means for receiving the output prints from said modules and transporting such prints serially downstream to form multi-print-page packets, and (iii) means for providing digital representations of a plurality of page images respectively to said printing modules, a fault control system for reducing delay due to a fault occurrence, a printing module, said fault control system comprising:

• (a) means for signaling the occurrence of a fault in an identified module;
• (b) a spare printing module located at the downstream end of said array of printing modules;
• and
• (c) means for cascading the digital page image representations respectively downstream one module from the faulty module through to said spare module.