Bypass Flow Passage Prevents Filter Clogging in Liquid Ejecting Heads
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Solution Overview
Problem
Ink-jet recording apparatuses face issues with air bubbles trapping in filters, leading to clogged filters and obstructed circulatory flow, which decreases print performance.
Innovation Solution
A liquid ejecting head design featuring a bypass flow passage with a larger inner diameter than the filter holes and nozzle openings, allowing air bubbles to escape and preventing filter clogging, while maintaining circulatory flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a filter is provided in the filter chamber to trap air bubbles, then air bubble removal is improved, but the filter becomes clogged up when air bubbles cover the upper surface, obstructing circulatory flow
Solution Approach 1:
The bypass flow passage acts as an intermediary path that mediates between the filter chamber and the circulatory system. When air bubbles accumulate in the filter chamber, they can escape through the bypass passage (which has higher flow resistance) rather than clogging the filter, thus maintaining both air bubble removal capability and circulatory flow continuity
Solution Approach 2:
The flow path is segmented into two separate passages: the main circulation passage with lower resistance for continuous ink flow, and the bypass passage with higher resistance for air bubble escape. This segmentation allows different functions (circulation and air removal) to occur simultaneously without interference
2Reliability
If the bypass flow passage has a larger inner diameter than filter holes, then air bubbles can escape more easily, but ink may flow into the bypass passage
Solution Approach 1:
The bypass flow passage is designed with specific parameter combinations: larger inner diameter than filter holes to allow air bubble passage, but higher flow resistance to prevent ink from flowing into the bypass under normal operating conditions. The parameters are optimized to exploit the difference in flow characteristics between air bubbles and ink
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
Prevents filter clogging and ensures uninterrupted ink circulation, enhancing the liquid ejection characteristics and print performance by allowing air bubbles to escape through the bypass flow passage.
Implementation Method 1
when air bubbles trapped by the filter join and grow to stagnate inside the filter chamber, the air bubble(s) can escape through the bypass flow passage
Implementation Method 2
a filter that is provided in a filter chamber traps air bubbles
Data Source
AI summary
A liquid ejecting head comprising, a plurality of nozzle openings, a first flow passage, a circulation flow passage, a filter chamber, and a bypass flow passage, an inner diameter of the bypass flow passage is larger than a diameter of the hole of the filter, the inner diameter of the bypass flow passage is larger than a diameter of the nozzle opening, and a flow passage resistance of the bypass flow passage is larger than a flow passage resistance of the circulation flow passage from a branch point where the bypass flow passage branches from the supply passage to a junction point where the bypass flow passage merges into the collection passage.