Serial Printhead Misalignment Compensation via Edge Mapping
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Solution Overview
Problem
Misalignment of serially arranged printheads in imaging devices leads to visible defects in image quality, particularly at cross-process edges, due to errors in mounting, manufacturing tolerances, and paper movement, which are not effectively compensated by existing systems.
Innovation Solution
A method that detects cross-process edges in image data and disproportionately maps image values to one or more printheads, allowing a single printhead to handle cross-process edges with reduced resolution while maintaining higher resolution in the process direction, thereby minimizing the visibility of printhead misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple printheads are arranged in series to increase pixel density, then image resolution is improved, but misalignment between printheads becomes visible
Solution Approach 1:
The patent applies local quality by differentiating how image values are mapped to printheads based on their location in the image. Cross-process edges are identified and handled differently from other areas - specifically, image values at cross-process edges are disproportionately mapped to favor one printhead over another, while other areas use equal distribution. This localized differentiation resolves the alignment issue at critical edge regions while maintaining the benefits of multiple printheads in other areas.
Solution Approach 2:
The patent changes the mapping parameter from equal distribution to disproportionate distribution based on edge detection. By detecting cross-process edges and adjusting the mapping ratio dynamically, the system adapts the image value distribution to compensate for printhead misalignment. This parameter change allows the system to maintain high resolution while accounting for manufacturing tolerances in printhead positioning.
2Measurement precision
If cross-process edges are printed with high resolution using multiple printheads, then image quality is improved, but misalignment visibility increases
Solution Approach 1:
The patent converts the harmful effect of printhead misalignment into a beneficial outcome by using disproportionate mapping. Instead of trying to eliminate misalignment entirely, the system accepts it and uses unequal image value distribution to compensate. By favoring one printhead for cross-process edges, the misalignment becomes less visible, effectively turning the manufacturing limitation into a workable solution that maintains both edge quality and alignment appearance.
3Ease of manufacture
If image values are evenly distributed to multiple printheads, then manufacturing complexity is reduced, but registration errors become visible
Solution Approach 1:
The patent applies preliminary action by detecting cross-process edges and determining disproportionate mapping ratios before actual printing occurs. The system pre-calculates which printhead should receive more image values at edge locations, allowing compensation for misalignment to be built into the printing process beforehand. This preliminary processing step ensures that registration errors are compensated without requiring complex mechanical adjustments to the printheads themselves.
Data Source
AI summary
A method processes image data for a color separation to reduce visible perception of misalignment of printheads in a plurality of serially arranged printheads. The method includes detecting cross-process edges in image values for objects in a color separation to be printed by a plurality of serially arranged printheads, and disproportionately mapping image values corresponding to the object in the color separation to one of the printheads in the plurality of serially arranged printheads.