Liquid Ejecting Head Circulating System Ink Thickening
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing liquid ejecting heads face issues with ink thickening near the ejection port due to evaporation of volatile components, leading to changes in ink ejection speed and direction, which can cause color unevenness and failure in ink ejection, especially when the pause time is long or the solid component of ink adheres to the ejection port, increasing fluid resistance.
Innovation Solution
A liquid ejecting head with a circulating system that includes a first and second ejection port configuration, where the second ejection port has an enlarged diameter portion radially outward from the first ejection port, and specific dimensions of the ejection port components (height, length, and width) to ensure a positive velocity component for ink flow, preventing ink retention and thickening by promoting continuous ink circulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ink is circulated within the print head to suppress thickening, then ink thickening is suppressed, but color unevenness occurs due to change in coloring material concentration
Solution Approach 1:
The patent applies local quality by creating a dedicated circulation flow path that is spatially separated from the ejection port region. The circulation path includes a circulation inlet positioned away from the ejection port and a circulation outlet that returns ink to a different location, ensuring that ink circulation occurs in a specific zone without directly affecting the ejection port's ink concentration and composition.
Solution Approach 2:
The patent segments the ink flow system into distinct functional zones: an ejection port region for ink ejection, a circulation path region for ink circulation, and separate inlet/outlet positions. This segmentation allows independent optimization of each zone - the circulation path can operate continuously to prevent thickening while the ejection port maintains stable ink composition for consistent ejection performance.
2Reliability
If pause time of not ejecting ink is long, then ink thickening is suppressed by circulation, but solid component adheres to ejection port increasing fluid resistance
Solution Approach 1:
The patent implements continuous ink circulation through the circulation path during pause periods when ejection is not occurring. The circulation pump maintains continuous flow through the circulation inlet and outlet, ensuring ink remains in motion and does not stagnate or adhere to the ejection port, thereby preventing increase in fluid resistance during extended pause times.
3Reliability
If ink circulation is implemented, then ink thickening is suppressed, but device complexity increases
Solution Approach 1:
The patent merges the circulation function with the existing ink supply and ejection system by integrating the circulation path into the overall ink flow architecture. The circulation inlet and outlet are positioned to work with the existing pressure chamber and ink supply mechanisms, allowing the circulation pump and flow path to be incorporated without requiring completely separate systems, thereby limiting the increase in device complexity.
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 suppresses ink thickening near the ejection port, maintaining ink flow and preventing color unevenness, even with high solid content inks, by ensuring continuous ink circulation and reducing evaporation rates, thus ensuring reliable ink ejection.
Implementation Method 1
a circulating system which circulates liquid within the liquid ejecting head
Implementation Method 2
an ejection energy generating element which generates energy for ejecting the liquid from the pressure chamber
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3C
AI summary
In a circulating system which circulates liquid within a liquid ejecting head (10), thickening of liquid in the vicinity of an ejection port (11, 21, 23, 26, 28, 30) can be more securely suppressed. The ejection port (11, 21, 23, 26, 28, 30) includes a first ejection port (11) disposed in an upstream side in an ejecting direction of ink and a second ejection port (21, 23, 26, 28, 30) disposed in a downstream side in the ejecting direction. The second ejection port (21, 23, 26, 28, 30) includes an enlarged diameter portion whose diameter is enlarged in a radially outward manner from at least a part of an opening edge portion of the first ejection port (11).