Lithographic web-fed rotary printing press

A printing unit for a web-fed rotary printing press for alternatively printing only a first web in a perfecting mode and for printing the first web and a second web in a non-perfecting mode, wherein the first and second webs travel through the printing unit from an upstream end to a downstream end thereof, the printing unit comprising:

• a first impression cylinder having
• at least a first and a second blanket cylinder arranged around at least a portion of a periphery of the first impression cylinder,
• at least a first and second plate cylinder, the first plate cylinder being associated with the first blanket cylinder, and the second plate cylinder being associated with the second blanket cylinder,
• a first direct imaging device for applying a first image to the first plate cylinder,
• a second direct imaging device for applying a second image to the second plate cylinder,
• means for cooperatively activating and deactivating the first and second plate cylinders and the first and second direct imaging devices,
• said means adapted to activate the first direct imaging device to apply the first image to the first plate cylinder while the second plate cylinder is in a printing position, and said means further adapted to activate the second direct imaging, device to apply the second image to the second plate cylinder while the first plate cylinder is in a printing position;
• and
• a second impression cylinder located adjacent to the first impression cylinder, the second impression cylinder having a plurality of third blanket cylinders and a corresponding plurality of third plate cylinders arranged around at least a portion of a periphery of the second impression cylinder,
• wherein, in the perfecting mode, the first web is passed over the first impression cylinder to be printed on a first side thereof and is then passed through a gap between the first and second impression cylinders to the second impression cylinder to be printed on a second side thereof, and wherein, in the non-perfecting mode, the first web is passed over the first impression cylinder and the second web is passed over the second impression cylinder, and
• wherein the first and second impression cylinders are driven by separate motors.