Liquid Ejection Head Flow Path for Large Droplets Without Viscosity Rise
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Solution Overview
Problem
Liquid ejection heads face issues with increased liquid viscosity due to evaporation at the ejection port, leading to ejection defects and reduced landing accuracy, especially when the halt time after ejection is long.
Innovation Solution
The liquid ejection head design includes a configuration where the height of the liquid chamber exceeds the height of the individual supply flow path, with the sidewall of the liquid chamber coinciding with or overlapping the ejection port, ensuring efficient ink circulation and reducing viscosity by continuously replacing ink in the ejection port area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the height of the flow path and the thickness of the ejection port member are increased to increase the ejection amount per liquid droplet, then the ejection amount is improved, but the liquid may not flow into the entire ejection port part, causing an increase in liquid viscosity
Solution Approach 1:
The patent introduces a new dimensional parameter - the height of the flow path from the liquid supply source to the ejection port - to optimize liquid flow dynamics. By controlling this vertical dimension, the patent ensures adequate liquid circulation throughout the ejection port part while maintaining large droplet ejection capability, thus preventing viscosity increase in the ejection region
2Object-affected harmful factors
If liquid is caused to flow into the ejection port part to prevent increase in liquid viscosity, then the liquid viscosity is reduced, but the ejection amount per liquid droplet decreases
Solution Approach 1:
The patent applies different flow path characteristics to different regions: the flow path height is optimized in the liquid supply region to ensure adequate liquid circulation and prevent viscosity increase, while the ejection port region maintains dimensions suitable for large droplet formation. This localized optimization allows both low viscosity and large ejection amount to be achieved simultaneously
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 design effectively prevents the increase in viscosity at the ejection port, allowing for larger liquid droplet volumes with improved ejection stability and accuracy.
Implementation Method 1
a volatile component in the liquid evaporates from an ejection port from which the liquid is ejected, and thus a liquid viscosity in the vicinity of the ejection port may increase
Data Source
AI summary
A liquid ejection head including an ejection port forming part, a flow path forming part including a liquid chamber, and an individual supply flow path configured to supply liquid to the liquid chamber, and a substrate including a supply flow path configured to supply liquid to the individual supply flow path and an outflow flow path configured to cause liquid to flow out of the liquid chamber, wherein a height of the individual supply flow path is larger than a height from a surface of the liquid chamber facing the ejection port to the ejection port forming member, and when viewed from the direction perpendicular to the surface of the substrate, a sidewall surface of the liquid chamber on a side with the supply flow path (1) coincides with an end surface of the ejection port, or (2) is disposed within the ejection port.