Ejection Port Protrusion Orientation for Print Quality and Durability
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Solution Overview
Problem
Existing liquid ejection heads face issues with satellite droplets and mist formation, which affect print quality and can cause apparatus breakdown, as protrusions on the inner surface of ejection ports are prone to breakage during wiping operations and make it difficult to remove adhering liquid droplets or foreign substances.
Innovation Solution
A printing element substrate with protrusions on the inner surface of ejection ports, where the tip portions are positioned closer to the substrate than the outer periphery, reducing the likelihood of breakage during wiping and allowing effective removal of liquid droplets and foreign substances from the outer periphery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If protrusions are provided on the inner surface of ejection ports to reduce satellite droplets and mist, then print quality is improved, but the protrusions are prone to breakage during wiping operations
Solution Approach 1:
The invention repositions the protrusions from extending toward the ejection port opening to extending toward the substrate, changing the spatial dimension of the protrusion orientation. This dimensional change allows the protrusions to maintain their droplet-coalescence function while being protected from wiping operations that occur at the port opening surface.
Solution Approach 2:
The protrusions are positioned to extend toward the substrate before any wiping operation occurs, creating a configuration where the delicate protrusion structures are already protected by the substrate proximity. This preliminary positioning prevents contact between the protrusions and wiping members before damage can occur.
2Reliability
If ejection ports are formed in recessed portions to protect protrusions, then protrusion breakage is reduced, but it becomes difficult to remove liquid droplets and foreign substances from the outer periphery
Solution Approach 1:
Instead of recessing the ejection ports to protect protrusions, the invention changes the protrusion orientation to extend toward the substrate dimension. This maintains a flat or protruding port surface that remains accessible to wiping members, solving the cleaning accessibility problem while still protecting protrusions through their reoriented configuration.
3Object-generated harmful factors
If protrusions extend toward the ejection port opening to increase meniscus, then satellite droplet generation is reduced, but the protrusions come into contact with wiping members and break
Solution Approach 1:
The invention inverts the conventional protrusion orientation by making them extend toward the substrate instead of toward the ejection port opening. This reversal maintains the meniscus-modifying function (as protrusions are still present on the inner surface) while eliminating the harmful contact with wiping members that occurs when protrusions extend toward the opening.
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 reduces satellite droplet and mist formation, enhances print quality by ensuring protrusions remain intact, and facilitates efficient cleaning of the ejection ports, thereby maintaining apparatus stability and performance.
Implementation Method 1
an energy generating element disposed on one surface of the substrate and configured to generate energy for use in ejecting liquid
Implementation Method 2
protrusions on the inner surface of each of ejection ports that eject liquid to increase the meniscus between the protrusions to thereby decrease tailing of the ejected droplets, thereby reducing generation of mist
Data Source
AI summary
A printing element substrate includes a substrate, an energy generating element, and an ejection-port formed member. The energy generating element is disposed on one surface of the substrate and configured to generate energy for use in ejecting liquid. The ejection-port formed member includes ejection ports that eject the liquid. A protrusion protruding toward inside of each of the ejection ports is provided on an inner surface of the ejection port. In a surface of the ejection-port formed member remote from the substrate, a tip portion of the protrusion is positioned closer to the substrate than an outer periphery of the ejection port.