Liquid Ejection Head Vertical Port Positioning for Air Entry Prevention
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Solution Overview
Problem
Existing liquid ejection apparatuses face stability issues due to air entering the circulation path, leading to reduced pumping performance and ejection stability, particularly when the liquid surface recedes and air enters the circulation pump.
Innovation Solution
A liquid ejection head with a pressure control chamber where the outlet is positioned higher in the vertical direction than the discharge port, and the discharge port is positioned higher than the supply port, to prevent air from entering the circulation pump and maintain stable circulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the ink inlet port is positioned vertically higher than the ink supply port, then the circulation path is simplified, but air enters the circulation pump when the liquid surface recedes, reducing pumping performance and ejection stability
Solution Approach 1:
The patent applies vertical positioning strategy by arranging the outlet, discharge port, and supply port at different vertical heights. Specifically, the outlet is positioned highest, followed by the discharge port, and the supply port is lowest. This vertical arrangement uses gravity to ensure that the liquid surface remains above the supply port, preventing air entry while maintaining circulation path functionality.
Solution Approach 2:
The pressure control chamber serves as an intermediary component between the circulation pump and the ejection module. It includes a liquid reservoir that maintains a liquid surface above the supply port, acting as a buffer to prevent air from reaching the circulation pump while still allowing liquid to flow through to the ejection module.
2Device complexity
If air enters the circulation pump, then the circulation path remains simple, but pumping performance is reduced due to air damper effect, preventing desired circulation flow rate
Solution Approach 1:
The patent uses vertical positioning of components to create a gravity-assisted liquid barrier. The supply port is positioned at the lowest point, ensuring that the liquid surface in the pressure control chamber always remains above it, physically blocking air from entering the circulation pump and maintaining optimal circulation flow rate.
Solution Approach 2:
The patent converts the potential harm of air entry into a beneficial arrangement by positioning the outlet higher than the discharge port. This creates a liquid column that actively prevents air from reaching the pump, turning the vertical height difference into a protective mechanism that ensures continuous, air-free circulation.
3Ease of operation
If the liquid surface recedes, then the circulation path operates freely, but air enters the circulation pump, reducing pumping performance
Solution Approach 1:
The patent addresses liquid surface recession by using vertical positioning where the supply port is at the lowest point and the outlet is highest. This ensures that even when liquid is consumed or the surface recedes, the liquid level remains above the supply port due to the vertical arrangement, preventing air entry while maintaining free circulation operation.
Solution Approach 2:
The pressure control chamber with its liquid reservoir acts as an intermediary that decouples the liquid surface level from the pump operation. The reservoir maintains a sufficient liquid head above the supply port, ensuring that pump performance is not affected by variations in overall liquid level in the system.
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 the reduction in ejection stability by maintaining a stable liquid flow and preventing air from entering the circulation pump, ensuring consistent performance.
Implementation Method 1
in the pressure control chamber, an outlet during the liquid circulation in the circulation pump is positioned higher in a vertical direction than a discharge port to discharge the liquid to the ejection module, and the lowermost portion of the discharge port is positioned higher in the vertical direction than the uppermost portion of a supply port to which the liquid is supplied from the circulation pump
Data Source
AI summary
Provided are a liquid ejection head and a liquid ejection apparatus that can suppress reduction of the ejection stability. To this end, an opening of a circulation pump connected with a supply port is positioned higher than a discharge port in a vertical direction in a usage orientation of the liquid ejection head, and the discharge port is positioned higher than the supply port in the vertical direction or at the same height as that of the supply port in the vertical direction in the usage orientation of the liquid ejection head.