Inkjet Printhead Recirculation Pump for Nozzle Clogging
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Solution Overview
Problem
Inkjet printheads face issues with ink blockage and clogging due to air bubbles and pigment-ink vehicle separation (PIVS), leading to print quality degradation and increased ownership costs, with existing solutions being cumbersome and expensive.
Innovation Solution
An auxiliary pump resistor of irregular size and shape is placed between thermal inkjet chambers to create an inertial mechanism for fluid recirculation, maintaining nozzle density and resolution while addressing PIVS, air, and particle accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional inkjet printheads are used without recirculation, then device complexity is low, but ink blockage and clogging occur due to air bubbles and pigment-ink vehicle separation
Solution Approach 1:
The recirculation channel is integrated within the printhead structure, nesting the fluid recirculation pathway inside the existing printhead geometry. This allows the pump to circulate ink through channels that are already part of the printhead assembly, adding recirculation functionality without requiring external housing or separate circulation systems.
Solution Approach 2:
The recirculation pump serves dual functions: it pumps ink through the recirculation channel to prevent blockage, and simultaneously supplies ink to the firing chambers for normal printing operations. This merging of recirculation and supply functions into a single pump component reduces overall system complexity while maintaining reliability.
2Reliability
If servicing is performed before and after use to prevent clogging, then ink blockage is reduced, but productivity decreases due to servicing time and ink consumption
Solution Approach 1:
The recirculation pump continuously circulates ink through the printhead channels before printing occurs, pre-preventing pigment settlement and air bubble formation. This preliminary action ensures that the ink remains fluid and free of blockages before the actual printing process begins, eliminating the need for pre-servicing priming operations.
Solution Approach 2:
The recirculation pump operates continuously during non-printing periods and between printing jobs, maintaining constant ink movement through the printhead channels. This continuous action prevents pigment-ink vehicle separation and air bubble accumulation throughout storage and idle periods, ensuring immediate printing readiness without servicing interruptions.
3Manufacturing precision
If nozzle density is increased for higher resolution, then manufacturing precision improves, but device complexity increases making pump integration difficult
Solution Approach 1:
The recirculation channel is positioned in a different spatial dimension than the nozzle array, running parallel to and between the nozzle rows rather than interfering with the nozzle pitch. This dimensional separation allows high-density nozzle arrangements to be maintained while accommodating the recirculation pathway without increasing overall device complexity.
Solution Approach 2:
The recirculation pump is positioned at a specific location within the printhead assembly where it can access the fluid slot and connect to recirculation channels without interfering with the nozzle structure. This strategic local placement allows the pump to integrate with high-density nozzle configurations while maintaining manufacturing precision and avoiding excessive 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
This solution effectively prevents ink blockage and clogging, reducing decap time and ink consumption, and ensuring immediate printing readiness while maintaining standard nozzle pitch and density.
Implementation Method 1
An auxiliary pump resistor of irregular size and shape is placed between thermal inkjet chambers to create an inertial mechanism for fluid recirculation
Implementation Method 2
a thermal inkjet printhead ejects drops from a nozzle by passing electrical current through a heating element to generate heat and vaporize a small portion of the fluid within a firing chamber
Data Source
AI summary
A fluid ejection assembly includes a fluid slot, and a group of uniformly spaced drop generators, where each drop generator is individually coupled to the fluid slot through a first end of a drop generator channel and to a connection channel at a second end of the drop generator channel. The fluid ejection assembly includes a pump disposed within a pump channel located between two drop generator channels, and is configured to circulate fluid from the fluid slot, into the connection channel through the pump channel, and back to the fluid slot through the drop generator channels.