Patent ID: 7909216

Claim:
A web alignment device to align a web of continuous print medium having two outer edges and originating from an upstream device to a stable lateral position with respect to a printing system for further printing on said continuous web, the printing system having a drive system downstream of the web alignment device, the alignment device comprising: mechanical means for defining an entry position of the web, the web contacting the mechanical means in sliding or rolling, the web being supplied as a nearly tension free loop, braking means to reduce the tension-force per unit of medium width at the end of an alignment zone compared to the tension force per unit of medium width downstream as exerted by the drive system of the printing system, means defining a curved or partially curved first web movement trajectory including areas where the print medium slides in friction contact with a curved surface, the means for defining the curved or partially curved first web movement trajectory being located upstream of said braking means, the sliding zone of the curved or partially curved first web movement trajectory extending over a finite length L 1 satisfying the relation L 1>max(50 mm, P/ 4) where P corresponds to the width of the print medium, adjustable lateral guiding means with side guides on both side edges of the web adjustable in width to contact at either of the two outer edges or at both outer edges of said print medium, thus limiting the lateral movement dimension available for said print medium in two opposing directions, the adjustable guiding means extending over a finite second web movement trajectory of said print medium, wherein the finite second web movement trajectory with side guides on both side edges of the web extends in the upstream direction to further than said means for defining the entry position and comprises at least a part of the first trajectory where said print medium is in sliding contact with said means defining said curved or partially curved first trajectory, L 2 being the length of simultaneous side-guiding and support for sliding satisfying the relationship: L 2>⅔*max(50 mm, P/ 4).