Liquid Ejection Apparatus Differential Pressure Control
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Solution Overview
Problem
Existing liquid ejection apparatuses face challenges in maintaining a predetermined differential pressure between the supply and collection paths due to variations in resistance, leading to fluctuations in ink flow and pressure, which can result in uneven image density and defects in printed images.
Innovation Solution
A liquid ejection apparatus with a differential pressure generating unit and a flow resistance adjustment unit that measures pressures at various flow rates and adjusts the flow resistance to maintain a consistent pressure difference between the supply and collection paths, ensuring stable ink flow and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If two pressure adjustment tanks are used to generate predetermined differential pressure between supply path and collection path, then ink flow is generated in the passage, but the predetermined differential pressure cannot be generated when resistance errors occur in supply path or collection path
Solution Approach 1:
The patent introduces a feedback control mechanism where a pressure sensor detects the actual differential pressure between supply and collection paths, and a controller adjusts the flow resistance adjustment mechanism accordingly. This closed-loop feedback system compensates for resistance variations and ensures the predetermined differential pressure is maintained despite manufacturing tolerances or resistance changes over time.
Solution Approach 2:
The patent dynamically changes the flow resistance parameter by adjusting the opening degree of the flow resistance adjustment mechanism (such as a valve) based on feedback from pressure measurements. This parameter adjustment allows the system to compensate for resistance errors in supply or collection paths and maintain stable differential pressure under varying operating conditions.
2Productivity
If number of ejection openings increases in long head, then supply amount of ink increases, but flow amount fluctuation and pressure loss difference increase due to ejection duty fluctuation
Solution Approach 1:
The patent applies local quality control by providing individual pressure adjustment mechanisms for each print element board or group of ejection openings. Each local region can independently adjust its flow resistance to compensate for pressure variations caused by different ejection duties, ensuring uniform pressure distribution across the entire liquid passage even when some regions are actively ejecting while others are not.
Solution Approach 2:
The patent implements feedback control at the local level by equipping each print element board with pressure sensors and adjustment mechanisms. The system continuously monitors actual pressure in each region and automatically adjusts flow resistance to maintain uniform pressure distribution, compensating for fluctuations caused by varying ejection patterns across different openings.
3Reliability
If flow resistance adjustment mechanism is added to maintain differential pressure, then pressure stability improves, but device complexity increases
Solution Approach 1:
The patent merges multiple functions into integrated components. The flow resistance adjustment mechanism is combined with the pressure adjustment tanks, and the control system integrates pressure sensing, signal processing, and valve control into a unified assembly. This merging reduces the number of separate components and simplifies the overall structure while maintaining pressure stability.
Solution Approach 2:
The patent designs the flow resistance adjustment mechanism to serve multiple functions: it controls differential pressure between supply and collection paths, compensates for resistance variations, and maintains stable flow rates. This multi-functional approach eliminates the need for separate dedicated components for each function, thereby reducing device 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
The solution effectively generates a predetermined differential pressure even with varying resistances, stabilizing ink flow and preventing defects such as uneven image density, thereby improving the quality and consistency of printed images.
Implementation Method 1
differential pressure generating unit that includes a supply passage of the liquid supplied to the print element board and a collection passage of the liquid collected from the print element board, and is configured to generate a difference between a pressure of the liquid in the supply passage and a pressure of the liquid in the collection passage
Implementation Method 2
flow resistance adjustment unit provided in the supply passage and/or the collection passage
Data Source
AI summary
A liquid ejection apparatus using a liquid ejection head and ejecting a liquid from the liquid ejection head includes a liquid supply unit that has a supply passage of the liquid supplied to the liquid ejection head and a collection passage of the liquid collected from the liquid ejection head, and supplies and collects the liquid by generating a difference between a pressure of the liquid in the supply passage and a pressure of the liquid in the collection passage, and a flow resistance adjustment unit provided in the supply passage and/or the collection passage.