Moisture Protection in Fluid Ejector Actuators
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Solution Overview
Problem
Moisture intrusion into the electrical or actuating components of fluid droplet ejection devices can cause failure due to electrical shorting or degradation of piezoelectric material, reducing the device's lifetime.
Innovation Solution
Incorporating an absorbent layer inside a chamber adjacent to the substrate to absorb moisture and utilizing a channel in the housing that connects to a cavity with an absorbent material or a pump activated by a humidity sensor to vent moisture away from integrated circuit elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an absorbent layer is added inside the chamber to absorb moisture, then the reliability of actuators and integrated circuit elements is improved, but the device complexity increases
Solution Approach 1:
An absorbent layer is introduced as an intermediary component between the moisture source and the sensitive electrical components. This layer acts as a mediator that captures and holds moisture, preventing it from reaching the actuators and integrated circuit elements, thereby protecting them without requiring fundamental redesign of the device architecture.
Solution Approach 2:
The internal chamber space is segmented into functional zones: a moisture-absorbing region containing the absorbent layer and a protected region housing the sensitive electrical components. This segmentation allows the moisture management function to be isolated from the operational components, improving reliability while maintaining clear functional separation.
2Reliability
If a channel connecting to a pump activated by a humidity sensor is implemented to vent moisture, then the reliability is improved, but the device complexity and energy consumption increase
Solution Approach 1:
A humidity sensor is implemented to monitor moisture levels within the chamber and provides feedback control for the pump system. When humidity reaches a threshold level, the sensor triggers the pump to activate and vent excess moisture, creating a closed-loop control system that maintains optimal humidity levels while avoiding unnecessary pump operation.
Solution Approach 2:
The system uses its own operational byproducts - the heat generated during fluid ejection operations - to drive moisture evaporation and movement toward the vent channel. This self-service approach reduces the energy burden on the pump system while maintaining effective moisture management.
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 solution effectively prevents degradation and shorting of actuators and integrated circuit elements, extending the lifetime of the fluid ejector by reducing moisture levels and increasing air volume around the components.
Implementation Method 1
an absorbent layer inside the cavity
Implementation Method 2
The absorbent layer can include a desiccant. The desiccant can be desiccant is chosen from a group consisting of silica gel, calcium sulfate, calcium chloride, montmorillonite clay, molecular sieves, zeolite, alumina, calcium bromide, lithium chloride, alkaline earth oxide, potassium carbonate, copper sulfate, zinc chloride, and zinc bromide.
Data Source
AI summary
A fluid ejection apparatus includes a substrate having a plurality of fluid passages for fluid flow and a plurality of nozzles fluidically connected to the fluid passages, a plurality of actuators positioned on top of the substrate to cause fluid in the plurality of fluid passages to be ejected from the plurality of nozzles, a protective layer formed over at least a portion of the plurality of actuators, a housing component having a chamber, the chamber adjacent to the substrate, and an absorbent layer inside the cavity. The absorbent layer is more absorptive than the protective layer.