Inkjet Print Head Asymmetric Port Offset for Cavitation Reduction
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Solution Overview
Problem
Existing inkjet printing technologies experience surface damage due to cavitation in the bubble generation chamber, which reduces the durability of the heat generating element, despite measures like protective layers and offsetting the heat generating element's center line from the ink flow path.
Innovation Solution
The ink ejection head is designed with the ejection port and heat generating element arranged such that the center of the ejection port is shifted away from the center of the heat generating element, ensuring that at least part of the ejection port is outside the effective bubbling area, and bubble communication with air occurs first when the bubble volume is reduced, preventing bubble retention and cavitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the heat generating element is offset from the ink flow path center line, then cavitation damage to the heat generating element is reduced, but the ejection efficiency and droplet formation may be affected
Solution Approach 1:
The patent applies asymmetry by intentionally offsetting the heat generating element from the ink flow path center line. This asymmetric arrangement ensures that the bubble generation area does not coincide with the ink flow center, preventing cavitation damage to the heat generating element while maintaining effective ink ejection through the ejection port.
Solution Approach 2:
The patent implements local quality by creating different functional zones within the bubble generation chamber. The heat generating element is positioned to create bubbles in a specific local area that is offset from the ink flow path center, allowing bubble generation in one region while ink ejection occurs in another, thus protecting the heat generating element from cavitation damage.
2Reliability
If the bubble is allowed to communicate with external air during volume reduction, then cavitation occurrence is inhibited, but the ejection timing and precision may be affected
Solution Approach 1:
The patent applies preliminary action by designing the ejection port position and bubble generation area offset arrangement in advance. This pre-arranged configuration ensures that when the bubble reaches its maximum volume and begins to reduce, it naturally communicates with external air through the offset ejection port area, preventing cavitation before it can damage the heat generating element.
Solution Approach 2:
The patent uses the offset ejection port area as an intermediary zone. This intermediate area allows the bubble to communicate with external air during volume reduction without directly exposing the heat generating element to cavitation damage. The ejection port serves as a mediator that enables controlled air communication while protecting the sensitive heat generating element.
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 arrangement effectively reduces cavitation occurrence, enhancing the durability of the ink ejection head by ensuring that the bubble communicates with air before collapsing, thus preventing damage to the heat generating element.
Implementation Method 1
an electric signal is applied to a heat generating element to generate heat
Implementation Method 2
ink around the heat generating element in the bubble generation chamber is heated rapidly to the boiling point, i.e., is boiled, and forms a bubble on the heat generating element. As a consequence of this phase change
Implementation Method 3
This collapse of the bubble may cause surface damage within the bubble generation chamber. That is, surface cavitation may occur, and consequently, with the driving of the heat generating element, may damage the surface of the heat generating element
Data Source
AI summary
A print head, which ejects ink by using a method whereby a bubble generated by a heat generating element communicates with the air, and for which the occurrence of cavitation is deterred and the durability is improved, is provided. According to the print head, a bubble grows until the maximum volume is attained, and then, at a volume reduction step, communicates with the air. As a result, a liquid in a bubble generation chamber is ejected. An ejection port and the heat generating element are arranged so that the center of the ejection port is shifted away from the center of the heat generating element in a direction leading from an ink supply port to the ejection port.