Abstract: A system for correcting skew of a web of material being fed through a machine includes first and second pinch assemblies placed at a distance transversely to a direction of feeding. First and second stepper motors drive the first and second pinch assemblies, respectively. A control provides first and second pulse trains to drive the first and second stepper motors, respectively. A device determines a value for the skew of the web of material. A method for controlling the system includes establishing first and second corrective pulse train sections for the first and second stepper motors, respectively, in accordance with a determined skew value, and providing first and second pulse trains for driving the first and second stepper motors, respectively.

Abstract: A method of printing a receiving material wherein said receiving material is fed through a printer including a first and a second image-forming unit for substantially simultaneous printing of the front and back of said material in a transfer nip, whereby the two images are brought into register in the lateral direction with the receiving material by determining, prior to the formation of the images, a reference position at the transfer nip; forming the first image in such manner that that part of said image which corresponds to the said reference position in the transfer nip substantially coincides therewith; and also forming the second image in such a manner that part of said image which corresponds to the said reference position in the transfer nip substantially coincides therewith; and feeding the receiving material to the transfer nip in such manner that that part of said material which corresponds to the reference position coincides substantially therewith at the transfer nip.