Patent ID: 8720333

Claim:
A method of buffering and controlling tension of a print substrate moving through a web press with a sequence of variations in substrate velocity during a printing cycle, using a control system comprising a chassis, and first and second movable rollers and motors, the method comprising: supporting a loop of the print substrate on the first movable roller for an input side of the web press; receiving at least one function that defines a motion profile of the first and second movable rollers required to maintain tension of the print substrate; controlling, via the first motor, translational movement of the first movable roller, based on the at least one received function, relative to a position of the first motor to control the tension of the print substrate on the input side of the web press in a first direction; controlling output of the first motor, based on the at least one received function, to achieve a sequence of movements of the first movable roller arranged to control the tension of the print substrate on the input side of the web press based on the sequence of variations in velocity of the print substrate; supporting a further loop of the print substrate on the second movable roller for an output side of the web press; controlling, via the second motor, translational movement of the second movable roller, based on the at least one received function, relative to a position of the second motor to control the tension of the print substrate on the output side of the web press in a second direction that is generally opposite to the first direction to add tension to the print substrate, and in a generally same direction as the first direction to reduce tension in the print substrate; and controlling output of the second motor, based on the at least one received function, to achieve a sequence of movements of the second movable roller arranged to control the tension of the print substrate on the output side of the web press based on the sequence of variations in velocity of the print substrate.