Dynamic Stitch Correction for Staggered Jetting Modules
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Solution Overview
Problem
Page-width printing systems with staggered jetting modules face challenges in maintaining perfect alignment, leading to irregular pitch and density issues, resulting in artifacts like gaps or bands in the printed output, which conventional correction methods may not adequately address across all image content and density levels.
Innovation Solution
A method involving dynamic correction of nozzle alignments during production, where test patterns are used to calculate correction values based on image attributes like gray levels, allowing for real-time adjustments to ensure uniformity across the image tone scale, including coarse and sub-pixel corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional stitching methods with fixed correction values are used, then alignment between jetting modules is improved, but uniformity across different image density levels deteriorates
Solution Approach 1:
The patent implements dynamic correction values that adjust based on image density characteristics. The system analyzes the density level of image regions and applies different correction values accordingly - darker regions receive different correction than lighter regions. This dynamic adaptation resolves the contradiction by making the correction process responsive to actual image content rather than using fixed values, thereby maintaining both alignment precision and density uniformity across varying image conditions.
Solution Approach 2:
The patent changes the correction parameter based on image density levels. By measuring or estimating the density characteristics of different image regions, the system adjusts the correction values applied to stitch joints. This parameter change strategy allows the system to optimize alignment for each density level independently, resolving the contradiction between maintaining precise alignment and ensuring uniformity across different density regions.
2Reliability
If dynamic correction based on image attributes is applied, then uniformity across density levels is improved, but processing complexity increases
Solution Approach 1:
The patent applies local quality by treating different density regions of the image differently. Instead of applying a uniform correction across the entire image, the system identifies local density characteristics and applies region-specific correction values. This localised approach improves uniformity across the tone scale while keeping processing complexity manageable by focusing corrections only where needed rather than uniformly across all pixels.
Solution Approach 2:
The patent implements partial action by applying corrections selectively to specific regions based on their density characteristics. The system identifies stitch joint regions and applies dynamic correction primarily to these areas rather than processing the entire image uniformly. This partial application of correction reduces overall processing complexity while still achieving the desired uniformity improvement in the critical stitch regions.
3Object-affected harmful factors
If stitching masks are used to correct artifacts, then visible gaps and bands are reduced, but correction effectiveness varies across different image content
Solution Approach 1:
The patent transforms static stitching masks into dynamic correction values that adapt to image content. Instead of using fixed masks that work for all image types, the system calculates correction values based on actual image density attributes. This dynamic approach maintains the benefit of gap and band reduction while improving adaptability across different image content by responding to the specific characteristics of each image region.
Solution Approach 2:
The patent implements feedback by using measured or estimated image density attributes to inform the correction process. The system analyzes the density characteristics of image regions and uses this information to adjust correction values accordingly. This feedback mechanism ensures that corrections are tailored to the actual image content, improving both the reduction of visible artifacts and the adaptability across different image types.
Data Source
AI summary
A method of printing is described for a page-width printer including a line head having a plurality of jetting modules that are staggered in a page-width direction. In a set up procedure, a test pattern is printed using the nozzles of adjacent jetting modules, and the pattern is analyzed to detect a stitch error in the overlap regions. The results of this analysis is used to calculate a set of correction values to be applied to print data subsequently sent to nozzles of the adjacent jetting modules to make a correction for the stitch error. During a subsequent production run, the print data sent to the nozzles of the adjacent jetting modules is analyzed to sense an image content attribute, such as gray or density level, of the print data. These results of the analysis of the print data is then used to calculate a dynamic adjustment that is used to adjust the set of correction values calculated during the set up procedure. The line head is then used to print the corrected print data by applying the set of adjusted correction values to production print data subsequently sent to the jetting modules.