Inkjet Ejection Head Flow Direction Layout for Density Uniformity
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Solution Overview
Problem
Existing liquid ejection technologies suffer from density unevenness due to fixed relations between ink flow direction and ejection head movement, leading to landing position shifts and visible density variations in printed regions.
Innovation Solution
The solution involves configuring the ejection head with ejection openings where the direction of ink circulation in the pressure chamber is alternated relative to the scanning direction, ensuring that some openings have opposite circulation directions to others, thereby balancing ink ejection and reducing density unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the direction of ink flow at the ejection pressure generation part is fixed relative to the ejection head movement direction, then the ink ejection system is simple to control, but density unevenness occurs in the printed region due to landing position shifts
Solution Approach 1:
The ejection head is divided into multiple ejection opening groups (first group and second group), where each group has a different ink flow direction. This segmentation allows different regions of the ejection head to compensate for landing position shifts in opposite directions, thereby reducing overall density unevenness while maintaining simple control operation.
Solution Approach 2:
Different local regions (ejection opening groups) are assigned different ink flow directions tailored to their specific positions relative to the ejection head movement. This local differentiation ensures that each region's ink flow characteristics are optimized for its location, reducing density unevenness across the entire printed area while keeping the overall control system simple.
2Device complexity
If ink circulation direction is uniform across all ejection openings, then the ejection head structure is simple, but landing position shifts cause visible density variations
Solution Approach 1:
The ejection head structure is segmented into multiple ejection opening groups with different ink circulation directions. This segmentation increases structural complexity only locally within each group while maintaining overall simplicity, and effectively reduces density variations by compensating for landing position shifts in different directions.
Solution Approach 2:
The ink circulation directions are made asymmetric across different ejection opening groups rather than uniform. This asymmetric design introduces deliberate directional differences that compensate for landing position shifts, improving print density uniformity while adding minimal complexity to the ejection head structure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively reduces density unevenness by separating the landing positions of main droplets and satellites, resulting in improved printing quality by minimizing areas of low density in printed images.
Implementation Method 1
a liquid flow is generated in a pressure chamber
Data Source
AI summary
In a liquid ejection apparatus, density unevenness of initial ejection from ejection openings after ejection stop can be reduced in a region in which printing is performed by relative movement of an ejection head. The liquid ejection apparatus includes: an ejection head including ejection openings, pressure chambers communicating with the ejection openings, and a flow path communicating with each pressure chamber; a generation mechanism configured to generate liquid flow passing through each pressure chamber via the flow path and differentiate first and second directions of liquid flow for each ejection opening; a scanning mechanism configured to scan the ejection head in the first and second directions; and a control unit configured to perform printing by causing the scanning mechanism to scan the ejection head relative to a printing medium and ejecting liquid from the ejection openings of the first and second directions to a unit region.