Liquid Ejection Head Bubble Reservoir Layout for Stable Ink Ejection
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Solution Overview
Problem
Existing liquid ejection heads face issues with ejection errors due to bubbles entering the pressure chamber, leading to potential image defects, and require additional structures that increase the head's size and complexity.
Innovation Solution
A liquid ejection head design incorporating a printing element board with pressure chambers, supply and collection flow passages, and bubble reservoir units with varying volumes to manage pressure differences and trap bubbles away from the ejection ports, thus preventing errors without increasing the apparatus' size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separator structure and air vent region are added to separate air and liquid, then the liquid ejection head can handle bubbles, but the size of the head increases and ink may adhere to the separator structure
Solution Approach 1:
The invention extracts the bubble management function from the main ejection path by providing a separate bubble reservoir unit that connects to the circulation flow passage. Bubbles are diverted into this dedicated reservoir through the second opening, separating them from the pressure chamber and ejection ports. This extraction approach handles bubbles effectively without requiring a large separator structure within the head body.
Solution Approach 2:
The invention segments the flow passages into distinct functional zones: a supply flow passage for ink delivery, a circulation flow passage for bubble collection, and a bubble reservoir unit for bubble storage. The first and second openings create separate communication paths that divide the bubble management function from the main ejection function, allowing compact integration while maintaining reliability.
2Reliability
If bubbles are guided to an air-liquid separator by inclining the circulation path, then bubbles can be separated, but the circulation path does not pass through the pressure chamber, creating ejection errors when bubbles enter
Solution Approach 1:
The invention introduces a bubble reservoir unit as an intermediary component between the circulation flow passage and the pressure chamber. The second opening acts as a mediator that allows bubbles to be transferred from the circulation path into the reservoir, preventing them from entering the pressure chamber while maintaining proper ink circulation through the first opening. This intermediary structure resolves the conflict between bubble separation and ejection accuracy.
3Device complexity
If the circulation path does not pass through the pressure chamber, then bubbles can be separated externally, but there is no circulation of fluid in the pressure chamber, risking ejection errors
Solution Approach 1:
The circulation flow passage serves multiple functions: it circulates ink through the pressure chamber to maintain fluid dynamics and prevent stagnation, and simultaneously provides a path for bubbles to be diverted into the reservoir. The first opening ensures continuous ink circulation through the pressure chamber for ejection stability, while the second opening enables bubble separation. This multi-functionality resolves the contradiction between simple circulation path configuration and ejection reliability.
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 managing bubbles in dedicated reservoir units, maintaining stable ink flow and reducing the risk of image defects while avoiding unnecessary size or cost increases.
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.