Skew correction system and method of controlling a skew correction system

• Main Authors: VENNER, CORNELIS W.M, LA VOS, PETER G, HOLTMAN, LODEWIJK T
• Format: Patent
• Language: English; French; German
• Published: 28.07.2010
• Subjects: CINEMATOGRAPHY; CONVEYING; ELECTROGRAPHY; ELECTROPHOTOGRAPHY; HANDLING THIN OR FILAMENTARY MATERIAL; HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS,CABLES; HOLOGRAPHY; MAGNETOGRAPHY; PACKING; PERFORMING OPERATIONS; PHOTOGRAPHY; PHYSICS; STORING; TRANSPORTING

A system for correcting skew of a web of material (1) being fed through a machine comprises first and second pinch assemblies (8,9) placed at a distance (”) transversely to a direction (X) of feeding; first and second stepper motors (11,13) for driving the first and second pinch assemblies (8,9), respectively; means (16-18) for providing first and second pulse trains (22,23) to drive the first and second stepper motors (11,13), respectively; and means (2-4) for determining a value for the skew of the web of material (1). A method for controlling the system includes establishing first and second corrective pulse train sections for the first and second stepper motors (11,13), respectively, in accordance with a determined skew value, and providing first and second pulse trains (22,23) for driving the first and second stepper motors (11,13), respectively, wherein the first pulse train (22) includes the first corrective pulse train section and a subsequent periodic succession (S 2A ) of pulses at a pre-determined nominal frequency, and wherein the second pulse train (23) includes the second corrective pulse train section and a subsequent periodic succession (S 2B ) of pulses at a pre-determined nominal frequency. The first and second corrective pulse train sections are established such as to commence the periodic successions (S 2A ,S 2B ) of pulses with phases differing between the first and second pulse trains (22,23) in accordance with the determined skew value.