Liquid-Discharging Head with Electro-Osmotic Ink Circulation
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Solution Overview
Problem
The evaporation of volatile components from the ejection orifice in liquid ejection heads leads to liquid thickening, increasing viscosity and causing ejection failures and color unevenness in images, as existing methods like ACEOF do not effectively discharge concentrated liquid from the orifice.
Innovation Solution
A liquid ejection head design featuring a first and second liquid flow path with electrodes generating an electro-osmotic flow, ensuring continuous ink circulation and reducing ink retention in the pressure chamber, thereby maintaining ink freshness and preventing thickening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If liquid is ejected from the ejection orifice, then liquid is discharged to form an image, but volatile components evaporate causing liquid thickening and viscosity increase
Solution Approach 1:
The patent introduces fresh liquid into the pressure chamber before ejection occurs through a circulation flow path. This preliminary replenishment of fresh liquid prevents the liquid from thickening due to evaporation during the idle time between ejections, thereby maintaining ejection reliability without compromising ejection efficiency
Solution Approach 2:
The patent establishes a continuous circulation flow path that constantly moves fresh liquid through the pressure chamber. This continuous action ensures that the liquid in the pressure chamber is continuously renewed, preventing thickening and maintaining consistent ejection performance over time
2Reliability
If liquid circulates in the pressure chamber, then fresh liquid is introduced, but concentrated liquid stays inside causing thickening
Solution Approach 1:
The patent divides the flow path into distinct segments: a first flow path for introducing fresh liquid into the pressure chamber and a second flow path for discharging liquid from the pressure chamber. This segmentation allows independent optimization of each flow path to ensure effective liquid renewal without excessive complexity
Solution Approach 2:
The patent introduces a circulation liquid introducing hole that serves as an intermediary component to facilitate the introduction of fresh liquid into the pressure chamber. This intermediary structure enables the circulation function while maintaining relatively simple device architecture
3Loss of time
If idle time after ejection is long, then liquid has time to evaporate, but viscosity increases significantly causing ejection failure
Solution Approach 1:
The circulation system performs preliminary action by continuously introducing fresh liquid into the pressure chamber during idle time. This ensures that even when idle time is long, the liquid in the pressure chamber remains fresh and does not undergo significant evaporation, preventing viscosity increase and ejection failure
Solution Approach 2:
The continuous circulation flow path maintains useful action during idle periods by constantly renewing the liquid in the pressure chamber. This continuous liquid renewal counteracts the effects of long idle time, preventing the liquid from thickening and ensuring reliable ejection regardless of idle duration
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 electro-osmotic flow effectively circulates ink, reducing retention and thickening in the ejection orifice, enhancing ejection accuracy and minimizing color unevenness in images by maintaining a relatively fresh ink state.
Implementation Method 1
a first electrode positioned in the first liquid flow path, and a second electrode which is positioned in the second liquid flow path and generates an electro-osmotic flow in the liquid together with the first electrode
Data Source
Figure 1A~1D
Figure 2A~2D
Figure 3A~3C
AI summary
This liquid-discharging head 1 is provided with: a discharge port 12 for discharging a liquid; a first liquid flow path 13 which communicates with the discharge port 12, and through which the liquid flows; a second liquid flow path 14 which communicates with the discharge port 12 at the side of the discharge port 12 opposite to the first liquid flow path 13, and through which the liquid flows; a first electrode 21 which is positioned in the first liquid flow path 13; and a second electrode 22 which is positioned in the second liquid flow path 14, and which, in conjunction with the first electrode 21, generates an electroosmotic flow in the liquid.