Printed Recording Medium After-Treatment for Moisture Gradient Control
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Solution Overview
Problem
Printing with water-based inks on paper results in moisture gradients leading to inhomogeneous expansion and deformation of the paper surface, which is not fully equilibrated for hours and depends on storage conditions.
Innovation Solution
Applying a fluid, such as water or water additives, in non-printed regions more than in printed regions using an after-treatment device with an inkjet printing unit, a contact transfer element, and a control unit to equalize moisture content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If water-based print colors and printing inks are applied to paper, then printing quality is improved, but moisture gradients cause inhomogeneous expansion and deformation of the paper surface
Solution Approach 1:
The device applies fluid to non-printed regions before the paper can undergo excessive hydroexpansion, counteracting the moisture gradient effects in advance. The control unit calculates and applies compensating moisture to regions that would otherwise absorb excess moisture during printing and drying, preventing surface deformation before it occurs.
Solution Approach 2:
The system applies different amounts of fluid to different regions of the paper based on their specific moisture requirements. The control unit determines which regions are printed and which are non-printed, then applies fluid selectively to non-printed regions to create a more uniform moisture distribution across the entire paper surface.
2Shape
If fluid is applied to equalize moisture content, then paper expansion uniformity is improved, but additional equipment and space requirements increase
Solution Approach 1:
The device uses a printing unit that can perform dual functions: applying print colors/inks and applying fluid for moisture equalization. The same print heads and transport mechanism are used for both printing operations and the moisture equalization process, eliminating the need for separate application equipment and reducing overall system complexity.
Solution Approach 2:
The fluid application system is integrated with the existing printing unit and transport mechanism. The control unit coordinates fluid application with the printing process, using the same hardware infrastructure for both operations. This merging of functions reduces equipment requirements and space needs compared to having separate systems.
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
Reduces or eliminates moisture differences between printed and non-printed regions, ensuring uniform paper expansion and drying, without requiring expensive hardware or significant space.
Implementation Method 1
a contact transfer element, in particular a felt element or a blade element, to bring the fluid into contact with the front side of the recording medium over its entire area
Implementation Method 2
The surrounding non-printed regions have a moisture gradient relative to these printed regions. This moisture gradient leads to an inhomogeneous expansion of the paper (hydroexpansion)
Data Source
AI summary
A device and a method for after-treatment of a recording medium that has been printed to is provided. A fluid is applied onto the front side of the recording medium that has been printed to at least on its front side. The printed front side is contacted by a contact transfer element. The fluid is applied and/or distributed by the contact transfer element for after-treatment of the recording medium.