Anti-Curl Fluid Applicator for Inkjet Substrate Flatness
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Solution Overview
Problem
Inkjet printing systems face the issue of substrate curling due to the absorption and subsequent drying of aqueous inks, leading to shrinkage and unevenness, which affects the flatness and desirability of printed substrates.
Innovation Solution
A new printing system incorporates an anti-curl fluid applicator with an anilox roller and a pressure member having electrically insulated segments, which applies anti-curl fluid to the substrate opposite the inkjet printing area, using a switching network to selectively apply electrical energy and control the migration of anti-curl fluid to counteract curling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If aqueous ink is applied to the substrate for printing, then the substrate absorbs water and solvents causing shrinkage, but this shrinkage leads to substrate curling and loss of flatness
Solution Approach 1:
The patent applies anti-curl fluid to the substrate before or during the drying process to counteract the curling effect. The anti-curl fluid creates a weight imbalance that opposes the shrinkage-induced curling, thereby maintaining substrate flatness despite the inherent curling tendency caused by aqueous ink absorption and evaporation
Solution Approach 2:
The patent changes the physical-chemical parameters of the substrate surface by applying a liquid anti-curl fluid composition. This fluid modifies the surface properties and weight distribution, transforming the substrate's mechanical state to resist curling while the ink dries
2Reliability
If the substrate is dried after printing to remove water and solvents, then the drying process completes the ink fixation, but the drying causes the substrate to shrink and curl
Solution Approach 1:
The anti-curl fluid is applied in advance to counteract the dimensional changes that will occur during drying. The fluid's weight and distribution are specifically designed to offset the shrinkage forces that develop as water and solvents evaporate from the substrate
Solution Approach 2:
The anti-curl fluid acts as an intermediary substance between the substrate and the drying process. It mediates the dimensional stability during the transition from wet to dry state, allowing complete ink fixation while maintaining substrate shape
3Stability of the object's composition
If humectants and moisture remain in the substrate after drying, then the substrate retains some flexibility, but the remaining moisture continues to cause shrinkage and curling for days after printing
Solution Approach 1:
The anti-curl fluid provides immediate counter-balancing weight to offset curling forces, acting throughout the extended period when humectants and moisture gradually evaporate. This preliminary anti-action maintains flatness throughout the multi-day drying and stabilization process
4Productivity
If significant curl occurs in the substrates, then the curled substrates fill the output tray, but this unevenness creates issues for stacking and reduces the desirability of printed sheets
Solution Approach 1:
By applying anti-curl fluid before substrates leave the printer, the system ensures substrates remain flat throughout handling and stacking operations. This eliminates the operational difficulties associated with stacking curled substrates while maintaining normal production throughput
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 system effectively reduces substrate curling by applying anti-curl fluid strategically, maintaining the original size and flatness of printed substrates, even after drying, without significant increases in drying complexity or temperature.
Implementation Method 1
an anilox roller... positioned so a portion of the anilox roller rotates in the anti-curl fluid in the reservoir and another portion of the anilox roller forms a nip with the pressure member
Implementation Method 2
a switching network configured to independently and selectively apply electrical energy to the segments of the pressure member
Data Source
AI summary
An aqueous ink printer includes an anti-curl fluid applicator that applies anti-curl fluid to a side of a substrate that is opposite a side that bears or will bear an ink image. The anti-curl fluid applicator includes a switching network that is configured to independently and selectively bias segments of a pressure member electrically. The segments are arranged along a longitudinal axis of the pressure member. The pressure member forms a nip with a anilox roller partially immersed in a reservoir of anti-curl fluid. As the switching network is operationed to selectively and independently bias the segments electrically using data corresponding to the ink image, anti-curl fluid migrates from the anilox roller onto the substrate in areas opposite the electrically biased segments.