Inkjet Printing Graininess Mitigation via Separate Passes
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Solution Overview
Problem
Image graininess, specifically overlay graininess and multi-color graininess, remains a significant issue in inkjet printing that cannot be comprehensively addressed using special inks or printheads, affecting the quality of printed products.
Innovation Solution
The method involves identifying distortable ink colors that interact when printed together and controlling the printhead and sheet feeders to print these colors in separate passes, with the dryer applying varying levels of drying between passes to ensure proper ink laydown and alignment, using heat-activated alignment marks for registration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple ink colors are printed in the same printing pass, then printing speed is improved, but graininess occurs due to irregular mixing of wet inks
Solution Approach 1:
The printing process is divided into multiple separate passes, with each pass printing a specific subset of ink colors. This segmentation prevents simultaneous contact of different wet inks, eliminating graininess while maintaining efficient production through optimized pass sequencing.
2Manufacturing precision
If ink colors are printed in separate passes, then graininess is reduced, but printing time increases
Solution Approach 1:
The system performs preliminary analysis of the print job to identify distortable ink color combinations before printing. This allows the controller to pre-determine the optimal printing pass sequence, ensuring that inks requiring separation are printed in different passes while minimizing the total number of passes and reducing overall printing time.
3Manufacturing precision
If sheets are dried between print passes, then ink alignment is improved, but energy consumption increases
Solution Approach 1:
The drying process is applied selectively based on the specific ink colors being printed. The system identifies which ink combinations require separation and applies drying only between those specific passes, rather than uniformly drying after every pass. This localized approach maintains alignment precision while minimizing unnecessary energy consumption.
4Measurement precision
If heat-activated alignment marks are used, then registration accuracy is improved, but the process complexity increases
Solution Approach 1:
Heat-activated alignment marks utilize thermochromic ink that changes color or becomes visible when exposed to heat from the dryer. This provides a simple, automated visual reference system for registration that leverages the existing drying process, avoiding the need for complex mechanical alignment systems or additional alignment components.
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
This approach significantly improves image smoothness and quality by allowing each ink color to dry before the next is applied, reducing graininess without the need for primers, thereby enhancing the overall image quality and reducing the need for multi-pass printing where not necessary.
Implementation Method 1
control the sheet feeders and a dryer of the printing apparatus to dry the ink printed on the sheets of media between the different print passes
Implementation Method 2
The heat-activated alignment marks become temporarily visible after being activated by the dryer
Data Source
AI summary
Printing methods and devices identify distortable ink colors in a print job. These distortable ink colors interact with one another when printed in the same printing pass on the same area of a sheet. These methods and devices control printheads and sheet feeders to separately print the distortable ink colors in different print passes.