Patent ID: 7841275

Claim:
A printing unit for printing a web of paper comprising: a frame; an upper printing group and a lower printing group, the upper printing group including an upper blanket cylinder and upper plate cylinder, the lower printing group including a lower blanket cylinder and a lower plate cylinder; a cylinder support and movement mechanism moving the printing unit into at least one throw-on configuration, an idle throw-off configuration, a blanket-changing throw-off configuration and a plate-changing throw-off configuration, and a controller for controlling the movement of the cylinder support and movement mechanism to move the upper and lower blanket cylinders and the upper and lower plate cylinders into the at least one throw-on configuration wherein the upper blanket cylinder is pressed against the lower blanket cylinder and the upper and lower blanket cylinders are pressed against the upper and lower plate cylinders respectively, the idle throw-off configuration wherein the upper blanket cylinder is spaced apart from the lower blanket cylinder, and the upper and lower blanket cylinders are spaced apart from the upper and lower plate cylinders respectively, so a web of paper printed by another printing unit passes through the print unit in a space between the upper and lower blanket cylinder without contacting any cylinder in the print unit, the blanket-changing throw-off configuration wherein the upper blanket cylinder is spaced apart from the lower blanket cylinder and the upper and lower blanket cylinders are spaced apart from the upper and lower plate cylinders respectively, the blanket-changing throw-off configuration being different from the idle throw-off configuration, and the plate-changing throw-off configuration wherein the upper blanket cylinder is spaced apart from the lower blanket cylinder, the upper and lower blanket cylinders are pressed against the upper and lower plate cylinders respectively, and a web of paper printed by another printing unit passes through a space between the upper and lower blanket cylinders, wherein in the blanket changing configuration, the upper blanket cylinder is moved upwards with respect to a position the upper blanket cylinder occupied in the at least one throw-on configuration and the lower blanket cylinder is moved downwards with respect to a position the lower blanket cylinder occupied in the at least one throw-on configuration, so a web of paper printed by another printing unit passes through the print unit in a space between the upper and lower blanket cylinders without contacting any cylinder in the print unit.