Positive pressure web wrinkle reduction system

1. A web-guiding system for guiding a web of media travelling from upstream to downstream along a transport path in an in-track direction, the web of media having a first side and an opposing second side, comprising:

a web-guiding structure including an exterior surface having a pattern of recesses formed into the exterior surface, wherein the web of media travels past the web-guiding structure with the first side of the web of media contacting at least some non-recessed portions of the exterior surface of the web-guiding structure;

an air source for providing an air flow between the first side of the web of media and the exterior surface of the web-guiding structure thereby producing a lifting force to lift portions of the web of media overlying the recesses away from the exterior surface of the web-guiding structure; and

wherein the air source is located downstream of the web-guiding structure and blows air between the first side of the web of media and the exterior surface of the web-guiding structure along a boundary where the web of media leaves contact with the web-guiding structure.

2. The web-guiding system of claim 1 wherein a direction of travel of the web of media is redirected by at least 2 degrees as it travels along the transport path past the web-guiding structure.

3. The web-guiding system of claim 1 wherein the exterior surface of the web-guiding structure is curved.

4. The web-guiding system of claim 1 wherein the web-guiding structure is a rotating roller.

5. The web-guiding system of claim 4 wherein a diameter of the exterior surface of the roller varies along a length of the roller to provide a convex or a concave surface profile.

6. The web-guiding system of claim 1 wherein the exterior surface of the web-guiding structure is provided by a fixed media support having a surface facing the web of media.

7. The web-guiding system of claim 6 wherein the exterior surface of the fixed media support has an arc-shaped cross-section.

8. The web-guiding system of claim 6 wherein the exterior surface is fabricated using a material having a coefficient of friction with the web of receiver of less than 0.2.

9. The web-guiding system of claim 1 wherein the recesses formed into the exterior surface of the web-guiding structure have rounded edges where they meet the non-recessed portions of the exterior surface of the web-guiding structure.

10. The web-guiding system of claim 1 wherein the recesses include a plurality of grooves that extend along at least a portion of the exterior surface of the web-guiding structure, each of the grooves being parallel to the in-track direction.

11. The web-guiding system of claim 1 wherein the air flow provided between the first side of the web of media and the exterior surface of the web-guiding surface varies as a function of cross-track position along a length of the web-guiding structure.

12. The web-guiding system of claim 11 , wherein the air source includes a manifold with openings that are aligned with the recesses to vary the air flow across a cross-track length of the web-guiding structure such that the lifting force is directed to the portions of the web of media overlying the recesses.

13. The web-guiding system of claim 11 wherein the air source includes an adjustable manifold providing an adjustable cross-track air flow profile.

14. The web-guiding system of claim 1 further including an air restrictor positioned on an opposite side of the web-guiding structure from the air source adapted to restrict the air flow which passes between the first side of the web of media and the exterior surface of the web-guiding structure.

15. The web-guiding system of claim 1 wherein the web-guiding system is a component of a printing system adapted to print on one or both sides of the web of media.

16. A web-guiding system for guiding a web of media travelling from upstream to downstream along a transport path in an in-track direction, the web of media having a first side and an opposing second side, comprising:

a web-guiding structure including an exterior surface having a pattern of recesses formed into the exterior surface, wherein the web of media travels past the web-guiding structure with the first side of the web of media contacting at least some non-recessed portions of the exterior surface of the web-guiding structure; and

an air source for providing an air flow between the first side of the web of media and the exterior surface of the web-guiding structure thereby producing a lifting force to lift portions of the web of media overlying the recesses away from the exterior surface of the web-guiding structure;

wherein the air source is located upstream of the web-guiding structure and blows air between the first side of the web of media and the exterior surface of the web-guiding structure along a boundary where the web of media first comes into contact with the web-guiding structure; and

further including a second air source, the second the air source being located downstream of the web-guiding structure and blows air between the first side of the web of media and the exterior surface of the web-guiding structure along a boundary where the web of media leaves contact with the web-guiding structure.

17. The web-guiding system of claim 16 wherein the web-guiding structure is a rotating roller.

18. The web-guiding system of claim 16 wherein the recesses include a plurality of grooves that extend along at least a portion of the exterior surface of the web-guiding structure, each of the grooves being parallel to the in-track direction.

19. The web-guiding system of claim 16 wherein the air flow provided between the first side of the web of media and the exterior surface of the web-guiding surface varies as a function of cross-track position along a length of the web-guiding structure.

20. A web-guiding system for guiding a web of media travelling from upstream to downstream along a transport path in an in-track direction, the web of media having a first side and an opposing second side, comprising:

a web-guiding structure including an exterior surface having a pattern of recesses formed into the exterior surface, wherein the web of media travels past the web-guiding structure with the first side of the web of media contacting at least some non-recessed portions of the exterior surface of the web-guiding structure;

an air source for providing an air flow between the first side of the web of media and the exterior surface of the web-guiding structure thereby producing a lifting force to lift portions of the web of media overlying the recesses away from the exterior surface of the web-guiding structure; and

an air restrictor positioned on an opposite side of the web-guiding structure from the air source adapted to restrict the air flow which passes between the first side of the web of media and the exterior surface of the web-guiding structure, wherein the air restrictor includes fingers or rollers that are positioned in the recesses between the first side of the receiver media and the exterior surface of the web-guiding structure.

21. The web-guiding system of claim 20 wherein the air source is located upstream of the web-guiding structure and blows air between the first side of the web of media and the exterior surface of the web-guiding structure along a boundary where the web of media first comes into contact with the web-guiding structure.

22. The web-guiding system of claim 20 wherein the web-guiding structure is a rotating roller.

23. The web-guiding system of claim 20 wherein the air flow provided between the first side of the web of media and the exterior surface of the web-guiding surface varies as a function of cross-track position along a length of the web-guiding structure.