Ink Jet Head Bypass Flow Paths for Stable Ejection
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Solution Overview
Problem
Ink jet recording apparatuses face challenges in maintaining stable ejection characteristics due to ink thickening and circulation stream interference, where high circulation speeds reduce ejection efficiency and low circulation amounts lead to ink shortages, especially with increased nozzle numbers.
Innovation Solution
A liquid ejecting head with bypass flow paths connecting liquid storage sections, where the flow path resistance of bypass paths is lower than the resistance through pressure generation chambers, allowing most liquid to flow through bypass paths, reducing circulation speed and preventing ink thickening, ensuring sufficient ink for ejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the circulation amount of the liquid is increased to prevent ink thickening, then the liquid flows faster inside the pressure generation chamber and prevents thickening, but the liquid is hardly ejected from the nozzle opening and stable ejection is disturbed
Solution Approach 1:
The circulation path is segmented into two separate paths: a first circulation path through the pressure generation chamber with higher flow resistance, and a second bypass path with lower flow resistance. This segmentation allows the liquid to be divided into two streams, with most liquid taking the bypass path to maintain low circulation speed for stable ejection, while a small portion flows through the pressure generation chamber to prevent thickening.
Solution Approach 2:
Different parts of the circulation system are given different flow resistance characteristics. The first circulation path through the pressure generation chamber is designed with higher flow resistance to limit the circulation amount, while the second bypass path has lower flow resistance to accommodate the majority of liquid flow. This local differentiation in flow resistance enables the system to simultaneously achieve both prevention of thickening and maintenance of ejection stability.
2Reliability
If the circulation amount of the liquid is decreased to improve ejection stability, then the liquid flow inside the pressure generation chamber slows down, but ink shortage occurs when the number of ejection nozzles is increased and required ejection amount is increased
Solution Approach 1:
The circulation system is divided into two parallel paths that work together to satisfy different requirements. The first path through the pressure generation chamber provides sufficient liquid supply to prevent ink shortage, while the second bypass path maintains low overall circulation speed to preserve ejection stability. This segmented approach allows the system to meet both the quantity requirement and the stability requirement simultaneously.
Solution Approach 2:
The bypass path acts as an intermediary that carries the majority of liquid flow away from the pressure generation chamber, thereby controlling the circulation amount that actually enters the ejection system. This intermediary path enables the system to maintain sufficient overall liquid supply while limiting the disruptive circulation effect on ejection stability.
3Productivity
If the number of ejection nozzles is increased to improve productivity, then more liquid is required for ejection, but ink shortage occurs when the circulation amount is small
Solution Approach 1:
The dual-path circulation system segments the liquid flow to efficiently distribute liquid to multiple nozzles. The bypass path ensures sufficient overall liquid supply capacity to meet the increased demand from multiple nozzles, while the controlled flow through the pressure generation chamber maintains appropriate circulation levels. This segmentation enables the system to scale to multiple nozzles without encountering ink shortage.
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 enhances ejection characteristics by minimizing the impact of the circulation stream on ink ejection, preventing thickening, and ensuring a sufficient ink supply, resulting in improved printing quality.
Implementation Method 1
a pressure generation chamber (12) which communicates with a plurality of nozzle openings (13), respectively; a first liquid storage section (17) which communicates with each of the pressure generation chambers (12); and a second liquid storage section (29) which communicates with the pressure generation chamber (12) on the opposite side of the first liquid storage section (17)
Implementation Method 2
the flow path member (11) has a first and second bypass flow paths (35, 36) which connect the first and second liquid storage sections (17, 29), respectively in two locations of one end side and the other end side of a nozzle row
Data Source
AI summary
A ink jet type recording head which circulates ink between a first manifold and a second manifold via a pressure generation chamber is provided, the flow path member has a first and second bypass flow paths which connect the first and second manifolds, respectively in two locations of one end side and the other end side of a nozzle row on the outside of the nozzle row on which the nozzle openings are formed, and a relationship between a flow path resistance R of the first and second bypass flow paths, and a flow path resistance r of a flow path portion including the pressure generation chamber which connects the first and second manifolds is R<r/N (wherein, N is the number of all nozzle openings).