Printing Apparatus Forward Backward Scan Dot Pattern Balance
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Solution Overview
Problem
Existing printing techniques face challenges in maintaining image quality due to uneven distribution of image data during forward and backward scanning, and they do not effectively address inter-color printing position shifts that affect graininess and image quality.
Innovation Solution
A printing apparatus and method that generate first and second data for dot patterns in forward and backward scans, respectively, ensuring these patterns have either a blue noise or green noise characteristic and maintaining equal dot counts in both scans, while also differing between colors to improve graininess and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If image data is binarized using fixed patterns such as m x n index patterns, then the binarization process is simplified, but the amounts of image data printed forward and backward become uneven
Solution Approach 1:
The patent applies asymmetry by using different index patterns for forward and backward scanning directions. Instead of using the same fixed pattern for both directions, the system employs direction-specific patterns that compensate for the inherent asymmetry in printing mechanics, ensuring equal dot distribution despite the different scanning directions
Solution Approach 2:
The patent implements dynamics by making the index pattern selection dependent on the scanning direction. The system dynamically adjusts which index pattern is applied based on whether the current scan is forward or backward, allowing the binarization process to adapt to directional variations and maintain balanced dot distribution
2Device complexity
If a fixed thinning pattern is used for forward and backward printing, then the printing process is simplified, but it becomes harder to align the amounts of image data printed forward and backward
Solution Approach 1:
The patent applies asymmetry by implementing different thinning patterns for forward and backward scanning directions. The system recognizes that fixed thinning in both directions creates imbalance, so it introduces directional-specific thinning strategies that maintain simplicity while achieving precise dot distribution control
Solution Approach 2:
The patent applies local quality by customizing the thinning pattern according to the local scanning direction. Each scanning direction receives a thinning pattern optimized for its specific characteristics, allowing the system to maintain overall process simplicity while achieving precise local control over dot distribution
3Productivity
If the amounts of image data printed forward and backward are not made equal, then the printing process is simpler, but the dispersiveness of each pass deteriorates and image quality decreases
Solution Approach 1:
The patent applies periodic action by systematically alternating between forward and backward scanning with carefully designed index patterns. This periodic structure ensures that over the course of complete printing cycles, the dot distribution remains balanced and dispersiveness is maintained, while keeping individual pass processing efficient
Data Source
AI summary
A printing apparatus operable to form dots on a printing medium by repeating a forward scan and a backward scan comprises a generation unit configured to generate first data of a dot pattern to be formed in a forward scan and second data of a dot pattern to be formed in a backward scan. The generation unit generates the first data and the second data such that the dot pattern to be formed in the forward scan and the dot pattern to be formed in the backward scan have either a blue noise characteristic or a green noise characteristic as a spatial frequency characteristic, and the number of dots to be formed in the forward scan and the number of dots to be formed in the backward scan are substantially the same.