Liquid Ejection Head Pressure Control for Ink Flow Uniformity
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Solution Overview
Problem
Existing circulation-type liquid ejection apparatuses face issues with pressure variations and ink flow rate inconsistencies, leading to uneven ink drop volumes and image quality degradation, particularly in high-duty printing and when using thermal or piezo-type print heads.
Innovation Solution
The apparatus incorporates a liquid ejection head with a configuration of common and individual passages, along with pressure adjustment mechanisms set to different control pressures, to maintain optimal pressure and flow rates, ensuring consistent ink flow and reducing the impact of pressure differences and heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large amount of ink is supplied to an elongated liquid ejection head, then printing productivity is improved, but pressure difference around ejection openings increases causing non-uniform ink drop volume
Solution Approach 1:
The liquid ejection head is divided into multiple independently controllable ejection units, each with its own pressure adjustment mechanism. This segmentation allows individual pressure control for each ejection opening, compensating for pressure differences caused by high ink supply rates and maintaining uniform ink drop volumes across all ejection points.
Solution Approach 2:
Each ejection opening is equipped with its own pressure adjustment mechanism that can independently regulate local pressure. This local quality approach ensures that each ejection point receives appropriate pressure control tailored to its specific conditions, preventing non-uniform ink drop volumes even when overall ink supply is high.
2Productivity
If circulation pump operates at high speed, then liquid circulation rate is improved, but pressure variation around ejection openings increases
Solution Approach 1:
Pressure adjustment mechanisms with feedback control are provided for each ejection unit. These mechanisms continuously monitor and adjust local pressure to compensate for variations caused by high-speed circulation pump operation, maintaining stable pressure conditions despite high circulation rates.
Solution Approach 2:
The system dynamically adjusts pressure parameters at each ejection opening based on real-time conditions. When circulation pump operates at high speed, the pressure adjustment mechanisms modify local pressure parameters to counteract induced variations, maintaining stable ink flow conditions.
3Manufacturing precision
If multiple pressure control mechanisms are provided for each ejection opening, then ink flow uniformity is improved, but device complexity increases
Solution Approach 1:
The pressure adjustment mechanisms serve multiple functions: they control ink flow rate, regulate pressure, and compensate for variations caused by circulation pump operation. This multi-functionality reduces the need for separate dedicated components for each function, managing complexity while achieving uniform ink flow.
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 stabilizes pressure variations, enhances ink flow consistency, and improves image quality by preventing ink thickening and foreign substance accumulation, allowing for high-speed, high-quality printing across various printing duties.
Implementation Method 1
a pressure difference is generated between the supply path and the collection path, thereby generating an ink flow passing through an ejection opening
Data Source
AI summary
A liquid ejection apparatus of the invention is a liquid ejection apparatus including a liquid storage container that stores liquid, a circulation mechanism that circulates liquid in a circulation path, and a liquid ejection head fluidly-connected to the liquid storage container, the liquid ejection head having a plurality of ejection openings, wherein the liquid ejection head includes at least a pair of common passages and a plurality of individual passages that connect one of the pair of common passages to the other one of the pair of common passages and communicate with the plurality of ejection openings, respectively, and at least a pair of pressure adjustment mechanisms whose pressures are set to different control pressures is connected to respective upstream sides or downstream sides of the pair of common passages.