Nozzle Array Acoustic Streaming Debris Removal
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Solution Overview
Problem
Existing liquid projection devices, such as 'face-shooter' arrays, face issues with debris accumulation on the nozzle material layer, particularly when handling biological materials or volatile fluids, leading to clogging and requiring costly piezoelectric actuators for cleaning, which increases complexity and cost.
Innovation Solution
An asynchronous sub-firing regime is implemented, where nozzles are driven with sub-firing signals that create a ripple effect across the ejecting face, independent of firing signals, to clear debris by acoustic streaming, redistributing concentrated ink components back into the bulk fluid, reducing solid particle deposition near the nozzles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If piezoelectric actuators are added solely for cleaning, then debris removal effectiveness is improved, but device complexity and cost increase
Solution Approach 1:
The firing signals that normally operate the nozzles for liquid ejection are made to serve a dual function: they also generate acoustic streaming effects that clear debris from the nozzle inner faces. By adjusting the timing and characteristics of these existing signals, the system achieves cleaning functionality without adding dedicated piezoelectric actuators, thus maintaining reliability while reducing device complexity
Solution Approach 2:
The cleaning function is merged with the existing firing operation. The same acoustic fields used to eject liquid are also utilized to create streaming flows that remove debris. This combines two previously separate functions (liquid ejection and debris removal) into a single integrated process using the existing actuator infrastructure
2Device complexity
If sub-firing signals are used to clear debris, then device complexity is reduced, but cleaning effectiveness may be insufficient without dedicated actuators
Solution Approach 1:
The system dynamically utilizes the existing firing signals to create time-varying acoustic fields that generate streaming flows. By modulating the firing signal characteristics (timing, amplitude, frequency), the system creates dynamic fluid motion patterns that effectively transport debris away from nozzle surfaces, achieving adequate cleaning effectiveness with reduced complexity
Solution Approach 2:
The nozzle system serves itself by using its own operating signals to generate the cleaning effect. The firing signals intended for liquid ejection automatically create acoustic streaming that removes debris from the nozzle inner faces, eliminating the need for external dedicated cleaning actuators while maintaining effective debris removal
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 method effectively clears debris from the inner nozzle faces, reduces clogging, and maintains device performance without the need for dedicated piezoelectric actuators, enhancing operational efficiency and reducing maintenance costs.
Implementation Method 1
this provides the benefit of acoustic streaming in the region where the ink meets the actuating nozzles and this results in the clearing of debris or other build-up from the inner face of the nozzles
Implementation Method 2
each firing signal causing sufficient movement of a group of nozzles relative to the liquid such that liquid is projected as droplets
Data Source
AI summary
A method of producing droplets from a nozzle provided on a material layer, the method comprising the steps of supplying liquid to an inner end of an array of nozzles, the nozzles being split into M groups of one or more nozzles, generating one or more firing signals, each firing signal causing sufficient movement of a group of nozzles relative to the liquid such that liquid is projected as droplets from the outer face of the respective nozzles, generating one or more sub-firing signals associated with each group of nozzles, the one or more sub-firing signals causing movement of the group of nozzles which is insufficient to project liquid from the nozzles, the sub-firing signals of adjacent groups having a non-zero phase relationship, wherein the sub-firing signal(s) of at least one group of nozzles is independent of the firing signal(s) associated with that group.