Inkjet Ejection Device Flow-Through Recirculation
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Solution Overview
Problem
Thermal inkjet printheads face issues with startup and idle time, leading to ink wastage and reduced print speed due to increased viscosity from ink drying, especially in multi-color printers without effective maintenance solutions.
Innovation Solution
The implementation of a flow-through ejector design with multiple vias per color and a pump for ink recirculation, which maintains bulk ink flow through the nozzles, reducing viscosity and eliminating the need for waste 'spits' by keeping the ink fresh and preventing drying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If nozzles are left uncapped during idle time to maintain print readiness, then print speed is improved, but ink dries in the nozzles causing viscosity increase and requiring maintenance spits
Solution Approach 1:
The patent implements continuous ink circulation through the nozzle array during idle periods, ensuring that ink continuously flows through all nozzles to prevent drying. This maintains nozzle readiness without requiring maintenance spits, resolving the contradiction between maintaining print speed and preventing nozzle clogging.
Solution Approach 2:
The system performs preliminary circulation of ink through the nozzles before printing operations begin and during idle periods. This preliminary action prevents ink from drying in the nozzles, ensuring immediate print readiness without subsequent maintenance requirements.
2Reliability
If maintenance spits are performed to clear dried ink from nozzles, then nozzle functionality is restored, but ink is wasted and print speed is reduced
Solution Approach 1:
By maintaining continuous ink circulation through the nozzles during idle periods, the system prevents ink from drying in the first place. This eliminates the need for maintenance spits and the associated ink wastage, directly resolving the contradiction between maintaining nozzle functionality and reducing ink loss.
Solution Approach 2:
The circulation system allows the ink itself to prevent drying by continuously moving through the nozzles. The ink serves its dual function of both printing and self-maintenance, preventing the need for separate maintenance operations that waste ink.
3Quantity of substance
If recirculation occurs upstream of the ejector, then ink flow is maintained, but nozzles are not truly kept fresh requiring continued maintenance spits
Solution Approach 1:
The patent implements circulation specifically at the ejector level where the nozzles are located, rather than upstream. This local circulation ensures that ink directly contacts and flows through each nozzle, truly keeping them fresh and ready. The localized approach at the critical interface between ink supply and ejection resolves the contradiction between maintaining ink flow and ensuring nozzle readiness.
4Speed
If heater chip length is increased to improve print speed, then more nozzles are available, but waste ink from maintenance spits increases linearly
Solution Approach 1:
The continuous circulation system maintains ink freshness across the entire nozzle array simultaneously, regardless of the number of nozzles or heater chip length. This scales efficiently to page-wide printheads with thousands of nozzles, preventing the linear increase in waste ink that would otherwise accompany increased nozzle count.
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 significantly reduces ink wastage and maintains print speed by keeping nozzles fresh without the need for maintenance spits, even during extended periods of disuse, and addresses pressure drop issues in multi-color printers.
Implementation Method 1
an inkjet printhead according to an exemplary embodiment includes a pump positioned upstream of the array of ejectors
Implementation Method 2
The array of ejectors is arranged in a single row and extends along a x-axis. Each ejector includes a heater element
Implementation Method 3
Thermal inkjet printheads
Implementation Method 4
Each ejector includes a heater element
Implementation Method 5
Thermal inkjet printheads
Implementation Method 6
Evaporation of water from the ink in the nozzles causes the viscosity to increase significantly
Implementation Method 7
a flow feature layer disposed over the substrate, the flow feature layer comprising a plurality of flow features
Data Source
AI summary
A fluid ejection including a substrate having at least one fluid ejecting element adapted to eject a fluid, a flow feature layer disposed over the substrate, the flow feature layer including a plurality of flow features, a nozzle plate layer disposed over the flow feature layer, the nozzle plate layer including one or more nozzle arrays, each nozzle in each of the one or more nozzle arrays being in fluid communication with a corresponding flow feature of the plurality of flow features and a corresponding fluid ejecting element of the at least one fluid ejecting elements, at least one intake via through which fluid flows into the plurality of flow features, and at least one output via through which fluid flows out of the plurality of flow features.