Inkjet Nozzle Column Alternation for Banding Reduction
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Solution Overview
Problem
Inkjet printers face issues with banding due to variations in ink droplet ejection timing and dryness, leading to unevenness and visual recognition of uneven glossiness, particularly at the upper and lower ends of the printing medium, where differences in ink droplet landing times and surrounding dryness cause bleeding and shape variations.
Innovation Solution
The method involves alternating the use of first and second nozzle columns, where the second nozzle column is used less than 0.5 times the number of times the first nozzle column, reducing the blank time and minimizing differences in dryness by controlling the ejection and non-ejection intervals during scanning, ensuring consistent drying times and reducing printing unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of nozzles is increased to increase printing speed, then productivity is improved, but banding occurs due to variation in ink ejecting properties at switching portions
Solution Approach 1:
The patent applies preliminary action by performing overlap printing in advance at the boundaries between band regions. Specifically, dots are printed in overlapping regions before the main printing process, ensuring that when multiple nozzle columns work together, the boundary areas are pre-filled to prevent visible banding. This preliminary overlap printing compensates for potential variations in ink ejecting properties before they can manifest as quality issues.
Solution Approach 2:
The patent applies local quality by treating the boundary regions between bands differently from the main printing areas. The overlap printing is specifically applied at the switching portions where nozzle columns transition, creating a localized quality enhancement at these critical boundary areas. This ensures uniform appearance at the most vulnerable points while maintaining high-speed printing across the entire image area.
2Productivity
If the number of dots ejected in one scanning is increased to increase printing speed, then productivity is improved, but banding occurs due to difference in timing of ink droplet ejection
Solution Approach 1:
The patent applies preliminary action by pre-printing dots in overlap regions before the main high-speed printing process. This ensures that even when multiple dots are ejected in one scanning at high speed, the boundary areas are already prepared with ink, preventing visible banding caused by timing variations in droplet ejection across multiple nozzle columns.
3Productivity
If ink droplet ejection timing varies across multiple nozzle columns, then productivity is maintained, but printing unevenness occurs due to difference in degree of dryness
Solution Approach 1:
The patent applies local quality by specifically addressing the boundary regions between nozzle column coverage areas. Overlap printing is applied at these local boundary areas where drying time variations would be most noticeable, ensuring uniform appearance at the most critical points while maintaining high-speed printing across the entire image.
Data Source
AI summary
A liquid droplet ejecting method which includes forming an image which is configured by a raster which is completed using liquid droplet ejecting operations of n times by alternately repeating a transport operation, and a liquid droplet ejecting operation in which liquid droplets are ejected on the medium while moving a first head which includes a plurality of nozzles, and a second head which aligns on the upstream side of the first head, in a scanning direction which intersects the transport direction in a scanning manner, in which, in a liquid droplet ejecting operation after a liquid droplet ejecting operation in which a first nozzle column and a second nozzle column are used in one liquid droplet ejecting operation, the number of times m (blank time) in which a liquid droplet ejecting operation of not using the second nozzle column is continuously executed is less than 0.5n.