Multilevel Printing Ink Distribution for Banding Reduction
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Solution Overview
Problem
Multilevel printing processes, such as inkjet printing, face quality defects like banding due to manufacturing tolerances in printing heads, leading to inconsistent droplet size and spacing, which are not effectively addressed by existing multi-pass printing methods that result in loss of speed.
Innovation Solution
A process that assigns n+1 different values to each pixel based on tonal values, using a threshold value matrix to calculate and fix pixel values, allowing for single-pass printing by distributing ink coverage variably to compensate for systemic fluctuations in droplet size and spacing, thereby reducing quality defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multi-pass printing is used to compensate for manufacturing tolerances, then printing quality is improved, but printing speed deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing optimal droplet distribution patterns in lookup tables before the actual printing process. The system pre-processes compensation data for manufacturing tolerances, so that during single-pass printing, the pre-computed distribution patterns can be directly applied without requiring multiple passes, thus maintaining both high quality and speed
Solution Approach 2:
The patent changes parameters by dynamically adjusting droplet distribution parameters based on detected manufacturing tolerances. The system modifies droplet size, spacing, and placement parameters in real-time using stored compensation data, allowing single-pass printing to achieve the quality that previously required multiple passes with fixed parameters
2Manufacturing precision
If manufacturing tolerances in printing heads are reduced, then droplet consistency is improved, but device complexity increases
Solution Approach 1:
The patent applies self-service by enabling the printing system to automatically compensate for its own manufacturing tolerances through built-in detection and correction mechanisms. The system detects variations in droplet characteristics and automatically adjusts distribution patterns using stored compensation data, eliminating the need for external calibration equipment or complex manual adjustment mechanisms
Solution Approach 2:
The patent implements feedback by continuously monitoring actual droplet output and comparing it against target specifications. The system uses this feedback information to select appropriate compensation patterns from lookup tables and adjust droplet distribution in real-time, maintaining consistent quality without requiring overly precise manufacturing tolerances
3Productivity
If ink coverage is distributed uniformly, then printing speed is maintained, but quality defects like banding increase
Solution Approach 1:
The patent applies local quality by varying ink coverage distribution according to local requirements rather than applying uniform coverage across the entire image. The system analyzes local image characteristics and manufacturing tolerance variations, then applies tailored droplet distribution patterns from lookup tables to specific regions, preventing banding in areas prone to defects while maintaining overall printing speed
Solution Approach 2:
The patent implements dynamics by making ink coverage distribution adaptive rather than static. The system dynamically adjusts droplet placement and spacing based on real-time detection of manufacturing variations and local image characteristics, selecting from multiple pre-computed distribution patterns to optimize both quality and speed for each specific printing condition
Data Source
AI summary
A process for printing substrates includes assigning image dots of printer-ready copy to pixels of a multilevel map and assigning values to the pixels depending on the tonal value of the image dot for assigning n+1 different values, where n>1. Artifacts are prevented in multilevel printing processes by assigning threshold values of any threshold value matrix to the pixels of the multilevel map on which the printing is based with respect to their positions relative to the printing substrate, calculating tonal values of the image dot, fixing the values of the pixels depending on the threshold value and the tonal value of the assigned image dot, and printing the multilevel map on a printing substrate in a multilevel printing process, with different values representing different amounts of ink of a printed pixel. A screen assignment device assigns a value to a pixel of a multilevel map generated by an RIP.