Liquid Ejection Head Layout for Pump-Free Ink Circulation
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Solution Overview
Problem
Existing liquid ejection heads face challenges in maintaining efficient ejection and circulation characteristics due to the need for additional mechanisms like pressure adjusting mechanisms and pumps, leading to increased size and complexity.
Innovation Solution
A liquid ejection head design incorporating a first energy generating element for ejection and a second energy generating element for circulation, with a circulation flow passage and communication passages configured to enhance ink flow and circulation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a differential pressure system with pressure adjusting mechanism and pump is used to circulate ink, then ink circulation is achieved, but the recording apparatus main body and head become larger in size
Solution Approach 1:
The patent extracts the circulation function from the traditional differential pressure system by providing a separate circulation flow passage with its own energy generating element. This allows the circulation function to be independent and integrated within the head, eliminating the need for external pumps and pressure adjusting mechanisms, thereby reducing the overall size of the recording apparatus while maintaining ink circulation efficiency
Solution Approach 2:
The circulation flow passage is nested within the individual flow passage structure of the head. The circulation flow passage includes a circulation pressure chamber that is integrated into the existing head architecture, allowing the circulation function to be embedded within the ejection system without adding external components, thus reducing the volume of the recording apparatus
2Productivity
If additional mechanisms like pressure adjusting mechanism and pump are added to circulate ink, then ink circulation is improved, but device complexity increases
Solution Approach 1:
The patent extracts the circulation function from the traditional differential pressure system by providing a separate circulation flow passage with its own energy generating element. This allows the circulation function to be independent and integrated within the head, eliminating the need for external pumps and pressure adjusting mechanisms, thereby reducing the overall size of the recording apparatus while maintaining ink circulation efficiency
Solution Approach 2:
The energy generating element in the circulation flow passage serves multiple functions: it generates circulation flow to remove air bubbles, maintains ink level in the pressure chamber, and can work in conjunction with the ejection function. This multi-functionality reduces the need for separate dedicated components, thereby reducing device complexity while maintaining ink circulation efficiency
3Ease of manufacture
If chip configuration with energy generating elements is used, then integration is improved, but ejection characteristics and circulation characteristics need improvement
Solution Approach 1:
The patent applies local quality by providing different flow passage configurations for different functions: the individual flow passage for ejection has specific characteristics optimized for droplet ejection, while the circulation flow passage has characteristics optimized for circulation and air bubble removal. The circulation flow passage includes a circulation pressure chamber with specific geometry and connection to the ejection pressure chamber, creating localized flow patterns that improve both ejection and circulation characteristics while maintaining high integration
Solution Approach 2:
The patent introduces a new dimension to the flow passage design by creating a circulation flow passage that extends in a direction intersecting with the ejection port row. This three-dimensional configuration allows the circulation function to operate independently from the ejection function while maintaining integration. The circulation flow passage includes an inlet, pressure chamber, and outlet arranged in a specific spatial configuration that improves both ejection and circulation characteristics
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
Improves ejection stability and reduces waste ink by minimizing the need for preliminary ejections, thereby enhancing throughput and yield while maintaining ink quality.
Implementation Method 1
a first energy generating element generating energy for ejecting the liquid disposed inside of the pressure chamber from the ejection port
Implementation Method 2
a second energy generating element generating energy for causing liquid to flow... disposed on a side closer to the inlet than the first energy generating element in the circulation flow passage
Implementation Method 3
the communication passage allowing the outflow-side common flow passage and the inflow-side common flow passage to communicate with each other
Data Source
AI summary
In a liquid ejection head, a circulation flow passage has an inlet in which a liquid to a pressure chamber flows and an outlet from which a liquid from the pressure chamber flows out, the circulation flow passage in which the pressure chamber is arranged between the inlet and the outlet extends such that the inlet, the pressure chamber, and the outlet are aligned in this order, a second energy generating element is disposed on an inlet side than a first energy generating element, and a communication passage allowing an outflow-side common flow passage and an inflow-side common flow passage to communicate with each other has an outflow-side opening in the outflow-side common flow passage and includes an outflow-side communication passage formed on a side surface that is inclined such that the farther from the outflow-side opening in a first direction, the larger a width in a second direction.