Dot Pattern Control for Printing Graininess and Density
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Solution Overview
Problem
Existing printing technologies face challenges in maintaining image quality due to graininess and density unevenness caused by displacement of print positions during relative movement between the print head and the print medium, particularly in multi-pass printing processes.
Innovation Solution
The implementation of a robust pattern creation method, where two dot patterns with different tone values are superimposed to ensure that the increase in the number of dots from one pattern to another is controlled, maintaining consistent dot coverage and graininess even with displacement, by using a first creation unit for a first tone value and a second creation unit for a second tone value, ensuring the robust pattern characteristics are met.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-pass printing is performed with relative movement between print head and print medium, then printing productivity is improved, but print position displacement causes graininess and density unevenness
Solution Approach 1:
The printing process is divided into multiple passes, with each pass printing a portion of the image. By segmenting the printing into multiple scans and using robust patterns that are insensitive to displacement, the system achieves high productivity while maintaining image quality despite print position variations between passes.
Solution Approach 2:
Robust patterns are pre-designed and pre-calculated to inherently compensate for potential print position displacements. The threshold matrices and dot patterns are created in advance with built-in tolerance for displacement, so that even when print positions shift between passes, the superimposed dots maintain consistent coverage and graininess characteristics.
2Manufacturing precision
If threshold matrix is created for each print scan to stabilize dot coverage, then density unevenness is reduced, but graininess in original image remains conspicuous
Solution Approach 1:
The patent applies different processing strategies to different tonal regions. By controlling the number of dots in robust patterns based on local tone values and using different threshold matrix approaches for different density regions, the system maintains dot coverage stability while reducing conspicuous graininess in various parts of the image.
Solution Approach 2:
The patent changes parameters such as the number of dots in robust patterns, threshold values in threshold matrices, and dot patterns across different print scans. By dynamically adjusting these parameters based on tone values and displacement characteristics, the system optimizes both dot coverage stability and graininess reduction for different regions of the image.
Data Source
AI summary
The present disclosure aims to provide a high quality image without conspicuous graininess and density unevenness. An embodiment of the present invention is an apparatus for printing a plurality of dot patterns on a printing medium, the dot patterns being formed by substantially same color and substantially same dot diameter, the apparatus including: a first creation unit configured to create, based on a first tone value, a first dot pattern and a second dot pattern printed and superimposed on the first dot pattern; and a second creation unit configured to create, based on a second tone value larger than the first tone value, a third dot pattern having an equal or larger number of dots compared to the first dot pattern and a fourth dot pattern printed and superimposed on the third dot pattern and having an equal or larger number of dots compared to the second dot pattern.