Multi-Head Halftone Printing Layout for Mixed-Region Grain Control
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Solution Overview
Problem
Existing printing technologies face challenges in maintaining image quality when multiple print heads with overlapping nozzle rows form dots, leading to graininess and density variations due to positional deviations, especially in mixed regions where a single dither mask is reused across different overlapping regions.
Innovation Solution
A printing apparatus and method that utilizes a dither mask with specific pixel groupings and nozzle arrangements, including a first, second, and third head, with overlapping nozzle rows, and adjusts the dither mask elements based on the relative positions of these heads to minimize positional deviations and enhance dot distribution dispersibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single dither mask is reused across multiple overlapping regions, then the device complexity is reduced, but the image quality deteriorates due to changing relative positional relationships between mixed regions and the dither mask
Solution Approach 1:
The patent divides the printing system into multiple head units (first, second, and third head units) with overlapping nozzle rows. Each head unit processes specific regions (single regions and mixed regions), segmenting the overall printing task to manage dither mask application systematically across overlapping areas.
Solution Approach 2:
The patent applies different dither mask strategies to different regions: single regions (processed by one head unit) and mixed regions (processed by multiple overlapping head units). This local differentiation ensures optimal dot distribution characteristics in each region type, maintaining image quality despite positional deviations.
2Area of stationary object
If multiple head units with overlapping nozzle rows are used, then the printing width and coverage are improved, but graininess and density variations occur due to positional deviations in dot formation
Solution Approach 1:
The patent merges the output of multiple head units (first, second, and third head units) in overlapping regions to achieve wider printing coverage. The overlapping nozzle rows are positioned to create mixed regions where dots from multiple heads combine, expanding the effective printing area while maintaining quality through controlled dot distribution.
Solution Approach 2:
The patent modifies dither mask parameters and dot distribution characteristics specifically for mixed regions where multiple head units overlap. By adjusting dot formation parameters and using blue/green noise characteristics, the system compensates for positional deviations and maintains consistent image quality across the expanded printing area.
3Reliability
If dot formation positions between groups deviate from normal positions, then the image quality deteriorates significantly, but using traditional dither mask techniques only reduces the influence within a predetermined range
Solution Approach 1:
The patent changes dither mask parameters and dot distribution characteristics specifically for mixed regions to enhance robustness against positional deviations. By modifying these parameters, the system maintains reliable image quality even when dot formation positions deviate from normal positions, exceeding the performance of traditional dither mask techniques.
Solution Approach 2:
The patent implements dynamic dot distribution strategies that adapt to the specific conditions of mixed regions. The system adjusts dot formation characteristics based on the overlapping patterns of multiple head units, creating a dynamic response to positional variations that maintains image quality consistency.
Data Source
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AI summary
A printing apparatus includes a halftone processing section that uses a dither mask to determine whether or not to form a dot in each of a plurality of pixels constituting an output image based on an input gradation value of an original image, and a head unit that forms the output image on a medium based on a processing result of the halftone processing section, in which a direction in which a plurality of heads discharge a liquid is set as a first direction, a direction in which the medium is transported is set as a second direction, a direction orthogonal to the first direction and the second direction is set as a third direction, the output image includes a mixed region and a single region, a length of the mixed region in the third direction is a first length, a length of the single region in the third direction is a second length, and the number of elements of the dither mask in the third direction is N times or 1/N times a total number of the number of pixels corresponding to the first length and the number of pixels corresponding to the second length.