Fluid Ejection Die Recirculation Bypass for High Flux Duty Cycles
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Solution Overview
Problem
Fluid ejection dies face issues with particle settling and heat buildup due to bulk fluid recirculation, leading to reduced fluid flow and impaired performance, especially in high print flux duty cycles.
Innovation Solution
The implementation of a hybrid fluid circulation system that includes both recirculation and bypass passages to reduce particle settling and enhance cooling, allowing some fluid to bypass the fluid actuator, thereby maintaining consistent fluid flow and temperature across fluid ejectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bulk fluid recirculation is used to reduce particle settling, then particle settling is reduced, but pressure drop increases and fluid flow decreases
Solution Approach 1:
The fluid circulation path is segmented into two separate channels: a recirculation passage that forces fluid to flow across the fluid actuator to prevent particle settling, and a bypass passage that allows fluid to flow directly from inlet to outlet to maintain high flow rate. This segmentation resolves the contradiction by allowing each channel to optimize for its specific function.
Solution Approach 2:
The bypass passage acts as an intermediary pathway that mediates between the recirculation system and the main fluid flow. It provides an alternative route that reduces the overall pressure drop while the recirculation passage maintains particle suspension through active fluid movement across the actuator.
2Temperature
If bulk fluid recirculation is used to cool the fluid ejection die, then cooling is improved, but fluid flow through the actuator is reduced
Solution Approach 1:
The cooling function is segmented from the main fluid flow path. The bypass passage provides a dedicated cooling channel that allows high-volume fluid flow for heat removal without interfering with the actuator flow. This separates the thermal management function from the ejection function, resolving the trade-off between cooling efficiency and flow rate.
3Productivity
If high print flux duty cycles are used to meet print demands, then productivity is improved, but heat buildup increases
Solution Approach 1:
The bypass passage serves as a thermal mediator that carries excess heat away from the die through high-volume fluid flow. This intermediary cooling path enables high print flux duty cycles by providing a dedicated heat removal mechanism that operates independently of the print ejection flow, allowing sustained high productivity without thermal damage.
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 approach enhances fluid flow, reduces pressure drops, and prevents air bubble accumulation and viscous plug formation, enabling reliable and consistent fluid ejection performance even at high duty cycles, while maintaining nozzle health and print quality.
Implementation Method 1
The recirculation passage is to supply fluid for ejection by the fluid actuator through an ejection orifice and to circulate fluid across the fluid actuator
Implementation Method 2
The bypass passage is to allow fluid to flow from the inlet channel to the outlet channel while bypassing the fluid actuator. The additional fluid flow across the bypass passage provides enhanced cooling of the fluid ejection die
Implementation Method 3
fluid ejection dies may include a fluid actuator that displaces fluid through an ejection orifice
Data Source
Figure 1~3
Figure 4A~4B
Figure 4C~4D
AI summary
A fluid ejection die may include a fluid actuator, a substrate supporting the fluid actuator, a chamber layer supported by the substrate and a bypass passage in the substrate. The substrate may include a closed inlet channel having an inlet opening for connection to an outlet of a fluid source and an outlet channel having an outlet opening of a first size for connection to an inlet of the fluid source. The chamber layer includes a recirculation passage to supply fluid for ejection by the fluid actuator through an ejection orifice and to circulate fluid across the fluid actuator from the closed inlet channel to the outlet channel. The bypass passage is of a second size less than the first size and connects the inlet channel to the inlet of the fluid source while bypassing any fluid actuator provided for ejecting fluid through an ejection orifice.