Liquid Ejection Head Overlapping Orifice Flow Control
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Solution Overview
Problem
Inkjet recording apparatuses face issues with viscosity rise and sedimentation of pigment in liquid ejection orifices due to infrequent use, leading to uneven image density and quality problems, especially in line heads where overlapping orifices are involved in image formation.
Innovation Solution
A liquid ejection head design with overlapping and non-overlapping ejection orifices, where the flow rate of liquid through branch flow paths is optimized, with more pump elements in overlapping orifices to maintain liquid circulation and prevent degradation, ensuring consistent ink ejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If overlapping ejection orifices are arranged to prevent image density unevenness, then image quality is improved, but the frequency of use of each orifice is reduced causing liquid viscosity rise and degradation
Solution Approach 1:
The liquid supply system is segmented into multiple independent branch flow paths, with each path dedicated to supplying liquid to a specific ejection orifice. This segmentation allows independent flow rate control for each orifice, enabling the overlapping orifices (which are used less frequently) to receive higher flow rates to prevent liquid degradation, while non-overlapping orifices receive lower flow rates.
Solution Approach 2:
Different flow rate characteristics are applied to different locations in the ejection orifice array. Overlapping ejection orifices are provided with higher liquid flow rates through their dedicated branch flow paths to prevent viscosity rise and liquid degradation, while non-overlapping ejection orifices receive lower flow rates. This local differentiation resolves the contradiction by tailoring the liquid supply characteristics to the specific usage pattern of each orifice group.
2Reliability
If liquid circulation is increased in overlapping orifices to prevent viscosity rise, then liquid ejection reliability is improved, but device complexity increases due to additional pump elements
Solution Approach 1:
The pump system is segmented into multiple independent pump elements, with each pump element dedicated to driving liquid circulation in a specific branch flow path. This segmentation allows individual control of liquid circulation in each branch, enabling targeted circulation enhancement in overlapping orifice regions without uniformly increasing complexity across the entire system.
Solution Approach 2:
Each pump element serves multiple functions: it drives liquid circulation in its dedicated branch flow path, prevents liquid degradation in the associated ejection orifice, and contributes to overall liquid supply stability. This multi-functionality justifies the addition of pump elements by demonstrating their comprehensive benefit to system reliability.
3Reliability
If branch flow paths are provided for each ejection orifice with optimized flow rates, then liquid degradation is prevented, but the device complexity and manufacturing cost increase
Solution Approach 1:
The liquid supply system is divided into multiple branch flow paths, with each path dedicated to a specific ejection orifice. This segmentation enables precise control of liquid flow rates to different orifices, allowing overlapping orifices to receive higher flow rates for degradation prevention while non-overlapping orifices receive lower rates, optimizing liquid quality maintenance.
Solution Approach 2:
Different flow rate characteristics are implemented in different regions of the liquid supply system. Overlapping ejection orifices are supplied with higher flow rates through their dedicated branch flow paths to prevent liquid viscosity rise and degradation, while non-overlapping ejection orifices are supplied with lower flow rates. This local differentiation optimizes liquid quality maintenance while managing system complexity.
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 design minimizes viscosity rise and sedimentation, resulting in high-quality images with reduced density unevenness and striped patterns by maintaining fresh ink circulation in frequently underused orifices.
Implementation Method 1
each of the plurality of branch flow paths includes a pump element for driving liquid circulation
Data Source
AI summary
A liquid ejection head comprises a plurality of ejection orifices for ejecting liquid, a liquid supply flow path for supplying liquid to the plurality of ejection orifices and a plurality of branch flow paths branched from the liquid supply flow path each being held in communication with corresponding one of the plurality of ejection orifices. The plurality of ejection orifices form a first row and a second row each extending in parallel with each other. The first and second rows of ejection orifices are partially overlapping with each other as viewed in the direction orthogonal relative to the extending direction. The flow rate in the branch flow paths held in communication with the ejection orifices located in the overlapping part is made greater than the flow rate in the branch flow paths held in communication with the ejection orifices located in the non-overlapping part.