Liquid Ejection Head With Asymmetric Bubble Reservoirs
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Solution Overview
Problem
Existing liquid ejection heads face issues with ejection errors due to bubbles entering the pressure chamber, which are not addressed by current technologies without increasing the size of the apparatus.
Innovation Solution
A liquid ejection head design incorporating a printing element board with pressure chambers, supply and collection flow passages, and bubble reservoir units to manage pressure differences and collect bubbles, preventing them from entering the ejection ports.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separator structure and air vent region are added to separate air and liquid, then bubble removal capability is improved, but the size of the head increases
Solution Approach 1:
The patent combines the bubble reservoir function with the existing pressure chamber structure. The pressure chamber serves dual purposes: as the ejection pressure chamber and as a bubble reservoir, eliminating the need for a separate bubble removal structure and avoiding increase in head size while maintaining bubble removal capability
Solution Approach 2:
The pressure chamber is designed to perform multiple functions: it serves as both the ejection pressure chamber and the bubble reservoir. This multi-functional design allows the system to remove bubbles without adding separate dedicated structures, thereby avoiding increased head size
2Reliability
If a circulation path with separator structure is implemented, then bubble collection is improved, but ink adherence to the separator structure occurs
Solution Approach 1:
The patent extracts the harmful separator structure from the circulation path and replaces it with a bubble reservoir that uses gentle circulation flow. Bubbles are removed from the ejection path and collected in the reservoir without requiring physical separation structures that cause ink adherence
Solution Approach 2:
The circulation flow acts as an intermediary mechanism to transport bubbles from the ejection path to the reservoir without direct contact between ink and separator structures. The flow field gently guides bubbles to the reservoir while minimizing ink loss through adherence
3Device complexity
If the circulation path does not pass through the pressure chamber, then the structure is simpler, but ejection errors occur when bubbles enter the pressure chamber
Solution Approach 1:
The patent implements preliminary bubble removal by circulating ink through the pressure chamber before ejection, allowing bubbles to rise to the reservoir and be removed in advance. This preliminary action prevents bubbles from interfering with the ejection process while maintaining a relatively simple circulation path structure
Solution Approach 2:
The circulation path continuously flows ink through the pressure chamber, maintaining constant bubble removal action. This continuous circulation ensures that bubbles are constantly being removed from the ejection path, maintaining ejection accuracy without requiring complex intermittent bubble removal mechanisms
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
The solution effectively suppresses ejection errors by guiding bubbles to reservoir units, maintaining stable ink ejection without enlarging the apparatus size or increasing waste ink production.
Implementation Method 1
a liquid feeding mechanism configured to generate a difference in pressure between the supply flow passage and the collection flow passage in such a way as to supply the liquid from the supply flow passage to the pressure chamber and to recover the liquid in the pressure chamber from the collection flow passage
Implementation Method 2
a first bubble reservoir unit connecting the supply flow passage to the liquid feeding mechanism, and a second bubble reservoir unit connecting the collection flow passage to the liquid feeding mechanism
Data Source
AI summary
A liquid ejection apparatus includes a printing element board, supply and collection flow passages, a liquid feeding mechanism, and first and second bubble reservoir units. The printing element board includes a pressure chamber having an ejection port from which the printing element board ejects a liquid. The supply and collection flow passages communicate with the pressure chamber. The liquid feeding mechanism generates a difference in pressure between the supply and collection flow passages to supply the liquid from the supply flow passage to the pressure chamber and to recover the liquid in the pressure chamber from the collection flow passage. The first bubble reservoir unit connects the supply flow passage to the liquid feeding mechanism. The second bubble reservoir unit connects the collection flow passage to the liquid feeding mechanism. A volume of the first bubble reservoir unit is larger than a volume of the second bubble reservoir unit.