Vacuum Pulldown for Print Media Buckling Prevention
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Solution Overview
Problem
In digitally controlled printing systems, the expansion and contraction of print media due to moisture content from inkjet printing cause dimensional changes, leading to image quality issues like buckling and creases, particularly when printheads are not aligned properly with the expanding media.
Innovation Solution
A printing system incorporating a vacuum assembly with a vacuum manifold aligned opposite non-print zones of lineheads to apply a vacuum force to the print media, adjusting its curvature and stiffness to prevent buckling and ensure proper alignment, while an adjustable vacuum manifold accommodates varying print media widths and densities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the print media is supported by rollers that create friction to prevent crosstrack sliding, then the print media is constrained from expanding freely, but this causes localized buckling and flute formation that degrades image quality
Solution Approach 1:
Instead of supporting the print media from below with friction-based rollers, the invention applies vacuum suction from the opposite side (above the media) to hold it flat. This reverses the support direction and mechanism, allowing the media to expand without friction-induced buckling while maintaining stability during printing.
Solution Approach 2:
The invention replaces mechanical friction-based roller support with a vacuum-based pneumatic system. The vacuum manifold creates negative pressure to hold the print media flat against the printing surface, eliminating the buckling and flute formation caused by friction constraints while maintaining media stability.
2Quantity of substance
If drying is applied frequently to remove moisture from the print media, then moisture content is reduced, but this causes dimensional changes that adversely affect image quality
Solution Approach 1:
Instead of applying drying action after every color layer, the system uses vacuum holding to prevent buckling during the printing process itself. This partial application of stabilization (only where and when needed during printing) allows moisture to remain without causing image quality degradation from repeated drying-induced dimensional changes.
Solution Approach 2:
The invention converts the harmful effect of moisture-induced expansion into a benefit by using vacuum suction to accommodate and control the expansion. Rather than fighting the expansion through drying, the vacuum system allows the media to expand while maintaining flatness, turning the moisture problem into a manageable condition.
3Adaptability or versatility
If the print media expands in the crosstrack direction, then moisture absorption is accommodated, but the friction from roller support prevents free expansion causing wrinkles and permanent creases
Solution Approach 1:
The invention reverses the support approach by applying vacuum from above rather than friction from below. This allows the print media to expand in the crosstrack direction freely while maintaining contact with the printing surface, preventing wrinkles and creases while accommodating moisture absorption.
Solution Approach 2:
The vacuum pneumatic system replaces friction-based mechanical support, enabling the print media to expand horizontally without being constrained by roller friction. The vacuum force normal to the media surface allows free in-plane expansion while maintaining flatness and preventing permanent deformation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The vacuum system effectively reduces the formation of flutes and wrinkles, maintaining image quality by ensuring the print media does not contact the support structure, thereby preventing smearing and moisture transfer, and allowing for uniform vacuum force application across different media widths.
Implementation Method 1
at least one vacuum assembly having a vacuum manifold disposed opposite a second side of the print media... outputs a vacuum force proximate to the second side of the print media
Data Source
AI summary
A printing system (500) includes one or more lineheads (206) disposed opposite a first side of a print media (212) and at least one vacuum assembly (506) having a vacuum manifold (508) disposed opposite a second side of the print media. The linehead or lineheads has one or more print zones (504) where a liquid or ink is deposited onto the first side of the print media. The vacuum manifold is aligned with a non-print zone (510) of each linehead and outputs a vacuum force proximate to the second side of the print media such that at least a portion of the second side of the print media (212) is deflected away from the lineheads. The printing system can also include another component, such as a dryer (208), disposed over the print media and laterally adjacent to the linehead (206). Another vacuum manifold can be disposed adjacent to the second side print media between the linehead and the component.