Liquid Ejection Head with Inclined Flow Path for Air Bubble Removal
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Solution Overview
Problem
Existing liquid ejection heads face issues with ejection failures due to air bubbles entering the pressure chamber, leading to concerns about ink solidification and increased head size, particularly in designs without fluid circulation through the pressure chamber.
Innovation Solution
A liquid ejection head design incorporating a printing element substrate with a pressure chamber, a first and second supply flow path, and a circulation pump, where the second supply flow path has a double the cross-sectional area and is inclined to facilitate gravitational guidance of air bubbles away from the pressure chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separator structure for separating gas from liquid is added to the liquid ejection head, then air bubbles can be removed from the liquid, but the size of the head increases
Solution Approach 1:
The patent extracts the air bubble removal function from a separate separator structure and integrates it into the circulation flow path itself. The inclined flow path design allows air bubbles to naturally separate and move toward the pump inlet without requiring additional separator components, thus removing the harmful function (air bubble accumulation) while maintaining compact head size.
Solution Approach 2:
The inclined circulation flow path acts as an intermediary mechanism between the pressure chamber and the pump. By designing the flow path with a specific inclination angle, air bubbles are guided along the inclined surface toward the pump inlet, serving as a passive air removal system without requiring active separation components.
2Device complexity
If fluid circulation through the pressure chamber is eliminated to simplify the structure, then the head size is reduced, but ejection failures occur when air bubbles enter the pressure chamber
Solution Approach 1:
The patent establishes continuous fluid circulation through the pressure chamber by designing a circulation flow path that passes through the pressure chamber and connects to the pump. This continuous circulation actively removes air bubbles from the pressure chamber, preventing ejection failures while maintaining structural simplicity without requiring separate air removal systems.
Solution Approach 2:
The circulation system serves itself by using the pump to drive fluid through the pressure chamber and back to the pump, creating a self-sustaining circulation loop. The inclined flow path design enables the system to automatically remove air bubbles without external intervention, making the ejection system self-maintaining and reliable.
3Reliability
If the circulation pump is positioned to create a pressure difference for fluid circulation, then air bubbles can be removed from the liquid, but the apparatus size increases
Solution Approach 1:
The patent merges the air removal function with the fluid circulation function by positioning the pump at the inlet of the inclined circulation flow path. The pump serves dual purposes: driving fluid circulation through the pressure chamber and simultaneously removing air bubbles that accumulate at the inlet. This integration eliminates the need for separate air removal devices, maintaining compact apparatus size while achieving effective air bubble removal.
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 design effectively suppresses ejection failures by guiding air bubbles away from the pressure chamber, maintaining stable ink flow without increasing the apparatus size.
Implementation Method 1
a circulation pump causing a pressure difference to occur between the first supply flow path and the first collection flow path so that liquid is supplied from the first supply flow path to the pressure chamber and liquid of the pressure chamber is collected from the first collection flow path
Implementation Method 2
a flow path inner wall inclined with respect to the gravitational direction and whose component force of a normal vector has a component in the gravitational direction
Implementation Method 3
guiding air bubbles away from the pressure chamber
Data Source
AI summary
A liquid ejection head and a liquid ejection apparatus suppressing the occurrence of an ejection failure without increasing the size of the apparatus are provided. To this end, between a circulation unit and a supply flow path communicating with a pressure chamber, a flow path is provided, having a vertical cross-sectional area in a liquid circulation direction, which is double or more a vertical cross-sectional area in a liquid circulation direction in the supply flow path and having a flow path inner wall inclined with respect to the gravitational direction and whose component force of a normal vector has a component in the gravitational direction.