Nozzle Geometry for Liquid Ejection Head Ink Retention
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Solution Overview
Problem
In liquid ejection heads, the retention of ink at steps in the nozzle due to varying cross-sectional areas leads to inefficient ejection, causing deterioration and potential ejection failure, as the liquid near the inner wall is hindered from moving downstream and accumulates, resulting in solidification and clogging.
Innovation Solution
The nozzle configuration features a first portion with a constant cross-sectional area in the ejection direction and a second portion with a smaller cross-sectional area, where the meniscus vibrates to accelerate ink flow, reducing retention by ensuring stable ink distribution and efficient ejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the flow path portion coupled upstream is made thicker than the portion including the opening end, then the liquid can be efficiently supplied from the flow path further upstream to the nozzle, but the liquid is retained at the step formed in the coupling portion and is not efficiently ejected from the nozzle opening
Solution Approach 1:
The invention applies local quality by creating a specific geometric configuration at the coupling portion where the upstream flow path connects to the nozzle. The upstream flow path has a larger cross-sectional area than the nozzle opening, forming a gradual transition rather than a sharp step. This local geometric modification ensures that liquid near the inner wall can smoothly transition into the nozzle flow without being trapped, while still maintaining efficient liquid supply from the upstream region.
2Productivity
If a step is formed in the coupling portion to increase upstream flow path area, then liquid supply efficiency improves, but liquid near the inner wall is hindered from moving downstream and accumulates
Solution Approach 1:
The invention employs curvature principles by designing a gradual transition region at the coupling portion between the upstream flow path and the nozzle. Instead of a sharp angular step, the geometry is configured to provide a smooth curved transition that guides liquid flow from the larger upstream cross-section into the smaller nozzle opening. This curved transition prevents liquid accumulation near the inner wall by ensuring continuous flow path without abrupt obstacles.
3Reliability
If the cross-sectional area of the flow path portion at the opening end is reduced, then the liquid can be more stably ejected from the opening, but the liquid is retained in the nozzle for a long time and deteriorates
Solution Approach 1:
The invention applies preliminary action by configuring the upstream flow path with a larger cross-sectional area before the nozzle opening. This pre-expansion allows liquid to be efficiently supplied and accelerated into the nozzle, ensuring that the liquid reaches the opening end with sufficient velocity and pressure. The gradual transition design ensures liquid is continuously fed into the nozzle without prolonged retention, preventing deterioration while maintaining stable ejection.
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 configuration ensures efficient ink supply and stable ejection by minimizing retention near the inner wall and at the nozzle's central axis, preventing clogging and maintaining ink quality over time.
Implementation Method 1
the meniscus vibrates to accelerate ink flow, reducing retention by ensuring stable ink distribution and efficient ejection
Data Source
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AI summary
A certain position in a nozzle in an ejection direction is a first position, a certain position downstream of the first position in the ejection direction is a second position, a substantially center in a second direction intersecting a first direction and the ejection direction is a third position, a certain position in the first direction is a fourth position, and a certain position that is closer to an end of the nozzle in the first direction than is the fourth position is a fifth position. A width of the nozzle width in the first direction at a position where the position in the ejection direction is the first position and the position in the second direction is the third position is a first width, a width of the nozzle in the first direction at a position where the position in the ejection direction is the second position and the position in the second direction is the third position is a second width, a width of the nozzle in the second direction at a position where the position in the ejection direction is the second position and the position in the first direction is the fourth position is a third width, and a width of the nozzle in the second direction at a position where the position in the ejection direction is the second position and the position in the first direction is the fifth position is a fourth width. The second width is smaller than the first width and the fourth width is larger than the third width.