Inkjet Printing Head Nozzle Row Shifting to Reduce Banding
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Solution Overview
Problem
Existing inkjet printing technologies suffer from banding issues, where overlapping scan bands result in visible streaks and vertical lines, leading to lower quality print images.
Innovation Solution
An inkjet printing device with a printing head featuring nozzle rows, a nozzle selecting unit, a main scan controlling unit, and a sub scan controlling unit, which selects and shifts activated nozzle rows to discharge ink at integer multiples of the image resolution, dispersing band boundaries and averaging print state variations across scans.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a part of the nozzle rows is selected as an activated nozzle row and the position of the activated nozzle row is changed to solve banding, then banding is reduced, but vertical lines become prominently visible in the print image
Solution Approach 1:
The nozzle rows are divided into multiple groups, and different groups are activated in different scans. This segmentation allows the printing to be distributed across multiple nozzle rows, preventing vertical lines from being consistently printed by the same nozzles and thereby reducing their prominence while also reducing banding effects.
Solution Approach 2:
The position of the activated nozzle row is changed periodically according to a predetermined rule. This periodic change in activation pattern ensures that no single nozzle or nozzle group is overused, which prevents the formation of prominent vertical lines and reduces banding by dispersing the printing load across different spatial positions over time.
2Productivity
If the activated nozzle row discharges ink continuously to improve printing speed, then productivity increases, but banding and vertical lines become more visible
Solution Approach 1:
The activated nozzle row is dynamically changed during the printing process according to a predetermined rule. This dynamic adjustment allows the system to maintain high printing speed by keeping nozzles continuously active while preventing banding and vertical lines by periodically switching which nozzles are active, thus distributing the printing workload and reducing repetitive patterns.
3Object-affected harmful factors
If the position of the activated nozzle row is changed frequently to reduce banding, then banding is reduced, but the complexity of the control system increases
Solution Approach 1:
The position of the activated nozzle row is changed periodically according to a simple predetermined rule rather than requiring complex real-time analysis. This periodic approach effectively reduces banding by dispersing print boundaries while maintaining relatively simple control logic that can be implemented through basic pattern repetition.
Solution Approach 2:
The system changes the parameter of which nozzle row is activated according to a predetermined pattern. This parameter change approach allows for effective banding reduction through systematic variation of nozzle activation while keeping the control mechanism relatively simple by using predetermined patterns rather than complex adaptive algorithms.
Data Source
AI summary
An aim is to provide a technique for obtaining a higher quality print image by reducing a banding caused upon printing using a printing head having nozzle rows. As a solution, an activated nozzle row is reselected each time when the activated nozzle row has discharged ink for a preset number of times, and in each scan, an interval by which the activated nozzle row discharges ink in a main scanning direction is set to be an integer multiple of a resolution of an image to be printed on a print medium in the main scanning direction.