Multi-Array Inkjet Head Arrangement for Bleeding Control
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Solution Overview
Problem
Conventional inkjet printers face issues with excessive ink ejection leading to bleeding and image quality degradation when printing with multiple colors, especially when using seven-color separation mode, as they often require high ink amounts per position, which can result in curling and cockling on paper media.
Innovation Solution
The use of a printing apparatus with six or more inkjet heads arranged in multiple arrays, where only one or two heads eject ink droplets simultaneously in the main scanning direction, reducing the number of colors mixed at each position and minimizing ink overlap, thereby decreasing the ink ejection amount and preventing bleeding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple inkjet heads eject ink droplets simultaneously onto the same position during main scanning, then color expression is achieved through subtractive color process, but ink ejection amount becomes excessive causing bleeding and image quality degradation
Solution Approach 1:
The inkjet heads are divided into multiple arrays (first array and second array) that are dislocated in the sub-scanning direction. This segmentation ensures that not more than two heads from the same array eject ink droplets simultaneously onto the same pixel position, thereby reducing the total ink ejection amount while maintaining color expression capability through coordinated operation of multiple arrays.
Solution Approach 2:
The patent introduces a spatial dimension solution by dislocating inkjet head arrays in the sub-scanning direction (orthogonal to the main scanning direction). This dimensional arrangement controls which heads can simultaneously eject onto the same position, reducing ink overlap from potentially four heads to maximum two heads per array, thus solving the excessive ink ejection problem.
2Manufacturing precision
If ink ejection amount to each position exceeds 120-150%, then color mixing is achieved, but bleeding between inks occurs and image quality degrades
Solution Approach 1:
By segmenting inkjet heads into multiple arrays with dislocated positions in the sub-scanning direction, the system limits simultaneous ink ejection onto any single position to maximum two heads per array. This segmentation prevents the harmful effect of ink bleeding by controlling the ink ejection amount to remain below the 120-150% threshold that causes bleeding.
3Productivity
If four color inks (Y, M, C, K) are used with inkjet heads disposed side by side in main scanning direction, then printing speed is maintained, but ink ejection amount reaches 200-400% causing curling and cockling on paper
Solution Approach 1:
The patent solves the excessive ink ejection problem by utilizing the sub-scanning direction dimension to dislocate inkjet head arrays. This allows the system to maintain high printing speed through parallel operation of multiple arrays while reducing ink ejection amount to maximum 200% (from two heads per array) instead of 400% (from four heads), preventing paper curling and cockling.
4Manufacturing precision
If seven-color separation mode is used with more inkjet heads, then higher definition printing is achieved, but ink ejection amount increases requiring reduction methods
Solution Approach 1:
The patent applies segmentation by dividing seven or more inkjet heads into multiple arrays dislocated in the sub-scanning direction. This allows higher definition printing through seven-color separation while controlling ink ejection amount by ensuring maximum two heads per array eject onto the same position, thus reducing total ink usage despite increased color capability.
Data Source
AI summary
A printing apparatus includes six or more inkjet heads, a carriage that is a head holder to hold a plurality of inkjet heads, a main scanning driver, and a sub-scanning driver. The carriage dividedly holds a plurality of inkjet heads in a plurality of arrays including at least a first array in which a plurality of inkjet heads are disposed side by side in a main scanning direction, and a second array in which a plurality of inkjet heads are disposed side by side in the main scanning direction while being dislocated in a sub-scanning direction with respect to the first array. Merely not more than two inkjet heads in the first array ejects an ink droplet, and merely not more than two inkjet heads in the second array ejects an ink droplet with respect to a position of each pixel in a single time of a main scanning operation.