Fluid Recirculation Channels for Inkjet Printheads
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Solution Overview
Problem
Inkjet printers face issues such as air bubbles blocking ink flow, pigment-ink vehicle separation leading to clogged nozzles, and increased ink viscosity, which degrade print quality and require frequent decapping and ink spitting, resulting in inefficiencies and waste.
Innovation Solution
The implementation of fluid recirculation channels with multiple sub-channels, pumps, and drop generators that allow for recirculation of ink during both idle and active operations, enabling higher nozzle density and efficient ink flow, reducing the need for decapping and ink spitting, and accommodating high solid load inks like UV curable inks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inkjet printers operate without fluid recirculation channels, then the device complexity is lower, but air bubbles block ink flow and pigment-ink vehicle separation clogs nozzles, degrading print quality
Solution Approach 1:
The fluid recirculation system is segmented into multiple sub-channels (first recirculation sub-channel and second recirculation sub-channel) that are fluidically coupled to the firing chamber. This segmentation allows independent recirculation paths for different functions: one sub-channel handles air bubble removal while the other manages pigment-ink vehicle separation, enabling targeted solutions for multiple flow problems without requiring a completely redesigned single-channel system.
Solution Approach 2:
The recirculation channels perform preliminary action by continuously circulating ink through the firing chamber even during idle periods before printing operations begin. This preliminary circulation prevents air bubbles from accumulating and keeps pigment particles suspended in the ink vehicle, addressing potential flow problems before they occur during actual printing, thereby maintaining ready-to-print conditions without frequent decapping.
2Productivity
If fluid recirculation channels are implemented, then ink flow is maintained and print quality improves, but the device complexity increases
Solution Approach 1:
The recirculation channel system serves multiple functions simultaneously: it removes air bubbles from the ink, prevents pigment-ink vehicle separation, maintains ink circulation during idle and active operations, and keeps nozzles clear. By consolidating these multiple functions into a unified recirculation architecture with interconnected sub-channels, the system achieves high productivity across various printing conditions without requiring separate mechanisms for each function, thereby limiting the increase in device complexity.
Solution Approach 2:
The recirculation channels maintain continuous ink circulation through the firing chamber during both idle and active printing operations. This continuity ensures that ink is constantly moved through the system, preventing stagnation, keeping pigment particles suspended, and maintaining ready-to-eject conditions in the nozzles. The continuous action eliminates the need for periodic decapping and ink spitting operations, significantly improving printing efficiency and productivity.
3Reliability
If decapping and ink spitting are performed frequently, then nozzle blockages are cleared, but ink waste increases and operational efficiency decreases
Solution Approach 1:
The recirculation channel system provides self-service by automatically maintaining nozzle functionality through continuous ink circulation. The first and second recirculation sub-channels work together to prevent air bubble accumulation and pigment separation at the nozzle level, keeping nozzles clear without requiring external intervention. This self-maintaining system eliminates the need for frequent manual decapping and ink spitting operations, thereby preventing ink waste while ensuring reliable nozzle function.
4Adaptability or versatility
If high solid load inks like UV curable inks are used, then ink compatibility and print quality improve, but ink viscosity increases and flow becomes difficult
Solution Approach 1:
The recirculation channel system applies hydraulic principles by using controlled fluid flow to manage high viscosity ink. The interconnected sub-channels create continuous circulation that applies gentle hydraulic pressure to move high solid load inks through the firing chamber, preventing stagnation and maintaining flow without requiring excessive pressure that could damage the system. This hydraulic approach enables the use of versatile inks like UV curable inks while managing their inherent viscosity challenges.
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 enhances print quality by maintaining ink flow, reducing decap time, and minimizing ink waste, allowing for higher efficiency and broader ink compatibility, thereby lowering operational costs and improving nozzle health.
Implementation Method 1
A number of pumps may be incorporated into the at least one pump channel
Implementation Method 2
passing electrical current through a heating element to generate heat and vaporize a small portion of the fluid within a firing chamber
Implementation Method 3
a piezoelectric inkjet printhead uses a piezoelectric material actuator to generate pressure pulses that force ink drops out of a nozzle
Data Source
AI summary
A fluid recirculation channel for dispensing a plurality of fluid drop weights includes a number of sub-channels. The sub-channels include at least one pump channel, and a plurality of drop generator channels fluidically coupled to the at least one pump channel. The fluid recirculation channel further includes a number of pump generators incorporated into the at least one pump channel, a number of drop generators incorporated into drop generator channels, and a plurality of nozzles defined within the drop generator channels, the nozzles being at least as numerous as the number of drop generators.