Liquid Ejection Head Vertical Flow Stabilization
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Solution Overview
Problem
Existing liquid ejection heads face instability in ejection due to the interface between the bubbling medium and the ejection medium, particularly when they flow side by side in a horizontal direction, leading to potential misalignment with the ejection port and inefficient ejection.
Innovation Solution
The liquid ejection head is designed such that the bubbling medium and the ejection medium flow in a vertical direction within a pressure chamber, with specific configurations of the liquid flow passages and pressure chambers to ensure stable parallel flows and laminar interfaces, using a confluence unit and lateral walls to manage the flow of liquids, allowing the ejection medium to be effectively ejected from the ejection port.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the bubbling medium and ejection medium flow side by side in a horizontal direction, then the liquid flow passage can be simplified, but the ejection stability deteriorates because the ejection medium may fail to come into contact with the ejection port
Solution Approach 1:
The patent transitions the flow arrangement from horizontal (width direction) to vertical (height direction) by introducing a lateral wall that divides the pressure chamber into upper and lower regions. This dimensional change ensures the ejection medium flows directly above the bubbling medium, guaranteeing contact with the ejection port while maintaining interface stability.
Solution Approach 2:
The pressure chamber is segmented into distinct upper and lower regions by the lateral wall, with the bubbling medium confined to the lower region and the ejection medium to the upper region. This segmentation prevents horizontal side-by-side flow and ensures proper vertical arrangement for stable ejection.
2Ease of manufacture
If the interface between bubbling medium and ejection medium is formed horizontally, then the flow passage design is simpler, but the ejection reliability worsens due to potential misalignment with ejection port
Solution Approach 1:
The interface between the two liquids is reoriented from horizontal to vertical by using the lateral wall to divide the pressure chamber into upper and lower regions. This vertical interface arrangement ensures the ejection medium is positioned directly above the bubbling medium, aligning with the ejection port for reliable ejection.
3Productivity
If thermal energy is applied to generate bubbles in the bubbling medium, then liquid ejection can be achieved, but the interface stability between the two liquids may be compromised
Solution Approach 1:
The lateral wall segments the pressure chamber to create distinct flow regions for the bubbling medium and ejection medium. This segmentation maintains a stable vertical interface between the two liquids, preventing mixing and ensuring the ejection medium remains positioned correctly for stable ejection even during bubble generation.
Solution Approach 2:
By arranging the liquids vertically rather than horizontally, the interface is oriented perpendicular to the direction of thermal energy application and bubble growth. This vertical arrangement maintains interface stability during the ejection process while still enabling effective bubble-driven ejection.
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 stabilizes the ejection of the ejection medium by maintaining a stable interface between the two liquids, ensuring reliable and efficient ejection, even with immiscible solvents like oil and water, and allows for the use of a wide range of liquids as the ejection medium, including high-density inks and other specialized fluids.
Implementation Method 1
a pressure generating element (12) which comes into contact with the first liquid (31) and generates pressure by applying thermal energy
Implementation Method 2
to eject the ejection medium along with growth of a bubble generated in the bubbling medium as a consequence of imparting thermal energy
Implementation Method 3
a liquid flow passage (13) in which a first liquid (31) and a second liquid (32) flow while forming an interface therebetween
Data Source
Figure 1
Figure 2
Figure 3
AI summary
In a liquid ejection head (1), a substrate (15) is provided with a first inflow port (20) located on an upstream side of a pressure chamber (18) in a direction of flow of liquids in a liquid flow passage (13) and configured to allow a first liquid (31) to flow into the liquid flow passage, a second inflow port (21) located on the upstream side of the first inflow port and configured to allow a second liquid (32) to flow into the liquid flow passage, and a lateral wall (51) extending in a direction of extension of the liquid flow passage. At least part of the lateral wall is located above the first inflow port. In the pressure chamber, the first liquid flows in contact with a pressure generating element (12) while the second liquid flows closer to the ejection port than the first liquid does.