Fluid Ejection Nozzle Membrane for Pressure and Refill Control
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Solution Overview
Problem
Fluid ejection devices face challenges in achieving both rapid nozzle refilling and sufficiently high pressure for efficient fluid ejection due to large leakage flow paths, and contamination issues from impurities that can clog or damage nozzles.
Innovation Solution
Incorporating an impedance feature, such as a membrane with apertures, in the fluid flow path to manage fluidic impedance at different frequencies and acting as a filter to prevent contaminants, while maintaining nozzle readiness and preventing clogging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If large leakage flow paths are used to refill the depleted nozzle quickly, then the nozzle refilling speed is improved, but the pressure at the nozzle opening becomes insufficient for efficient fluid ejection
Solution Approach 1:
The flow path is divided into segments with different impedance characteristics. The first passage has higher impedance to maintain pressure during ejection, while the second passage has lower impedance to enable rapid refilling. This local differentiation of flow path properties resolves the contradiction between pressure maintenance and refilling speed.
Solution Approach 2:
The flow path is segmented into a first passage and a second passage with different impedance levels. The first passage (with higher impedance) supplies fluid during ejection, while the second passage (with lower impedance) enables rapid refilling from the return channel. This segmentation allows simultaneous optimization of both pressure and refilling rate.
2Stress or pressure
If an impedance feature is added to the flow path to maintain high pressure during ejection, then the pressure at the nozzle opening is improved, but the refilling speed of the depleted nozzle decreases
Solution Approach 1:
The flow path is segmented into two distinct passages: the first passage with higher impedance for pressure maintenance during ejection, and the second passage with lower impedance for rapid refilling. This segmentation resolves the contradiction by assigning different functions to different flow path segments.
Solution Approach 2:
The system dynamically switches between different flow paths based on operational needs. During ejection, the first passage is active to maintain pressure; during refilling, the second passage is active to maximize flow rate. This dynamic utilization of flow paths resolves the time-pressure contradiction.
3Reliability
If a filter is added to prevent contaminants from reaching the nozzle, then the reliability of fluid ejection is improved, but the device complexity increases
Solution Approach 1:
The filter is merged with the impedance feature, combining two functions (pressure control and contamination filtering) into a single integrated component. This reduces device complexity while maintaining both reliability and pressure control capabilities.
Solution Approach 2:
The membrane structure serves multiple functions simultaneously: it acts as an impedance feature for pressure control during ejection and as a filter to prevent contaminant ingress. This multi-functionality reduces the need for separate components, thereby reducing overall device complexity.
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
The impedance feature allows for high pressures during ejection and rapid refilling of depleted nozzles, while the filter prevents contamination, enhancing the efficiency and reliability of fluid ejection.
Implementation Method 1
The impedance feature introduces a fluidic impedance into the leakage flow path that is higher at or around the jet resonance frequency than at other frequencies
Implementation Method 2
The jet resonance frequency is the frequency at which the nozzle has high fluid flow, such as during fluid ejection from the nozzle
Implementation Method 3
The impedance feature can be a membrane with apertures positioned in the fluid supply path
Data Source
AI summary
A fluid ejector includes a nozzle layer, a body, an actuator and a membrane. The body includes a pumping chamber, a return channel, and a first passage fluidically connecting the pumping chamber to an entrance of the nozzle. A second passage fluidically connects the entrance of the nozzle to the return channel. The actuator is configured to cause fluid to flow out of the pumping chamber such that actuation of the actuator causes fluid to be ejected from the nozzle. The membrane is formed across and partially blocks at least one of the first passage, the second passage or the entrance of the nozzle. The membrane has at least one hole therethrough such that in operation of the fluid ejector fluid flows through the at least one hole in the membrane.