Liquid Ejection Head Ink Circulation Viscosity Control
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Solution Overview
Problem
The existing liquid ejection heads face issues with color unevenness due to increased ink viscosity resulting from evaporation, particularly with inks having low moisture content, leading to poor image quality.
Innovation Solution
A liquid ejection head design that circulates ink between a tank and the ejection head, utilizing a thermal system to generate bubbles for ejection, with specific flow path configurations and pressure control mechanisms to manage viscosity and prevent ink stagnation, ensuring effective ink circulation and recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ink is circulated through a flow path to prevent viscosity increase, then ejection reliability is improved, but device complexity increases due to additional circulation components
Solution Approach 1:
The patent combines the circulation pump, flow paths, and ejection head into an integrated structure where the circulation channels are formed within the ejection head body itself. This merging of functions reduces the number of separate components and simplifies the overall device while maintaining the ink circulation capability needed for reliable ejection.
Solution Approach 2:
The ejection head structure serves multiple functions: it acts as both the ejection mechanism and the circulation channel housing. The flow paths are designed to serve dual purposes of ink delivery and circulation, eliminating the need for separate circulation piping and reducing device complexity.
2Productivity
If pause time after ejection is extended, then productivity is improved, but ink viscosity increases causing ejection failure
Solution Approach 1:
The circulation system maintains continuous ink flow through the ejection head even during pause periods between ejection cycles. This continuous circulation prevents ink stagnation and viscosity increase, allowing extended pause times without compromising ejection reliability, thereby improving productivity.
Solution Approach 2:
The circulation pump operates periodically to refresh the ink in the flow paths at regular intervals. This periodic circulation action prevents prolonged stagnation and viscosity buildup, enabling longer operational cycles while maintaining ejection performance.
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 reduces color unevenness by maintaining ink viscosity and preventing stagnation, ensuring high-quality image formation even with inks of low moisture content.
Implementation Method 1
a flow path in which an energy generating element, which generates an energy to be used for ejecting the liquid
Implementation Method 2
The liquid inside the flow path is circulated between the inside and the outside of the flow path
Data Source
AI summary
A liquid ejection head includes an ejection orifice for ejecting a liquid; a flow path in which an energy generating element is disposed, generates an energy to be used for ejecting the liquid; a liquid inside the flow path; an ejection orifice part that allows the ejection orifice and the flow path to communicate with each other; a supply flow path for supplying the liquid from the outside; and a recovery flow path for recovering the liquid to the outside. The moisture content of the liquid is 65 wt % or less. The liquid inside the flow path is circulated between the inside and the outside of the flow path.