Inkjet Printer Conduit Design for Bubble Removal
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Solution Overview
Problem
Inkjet printers face challenges in minimizing 'wake-up' times and efficiently purging air bubbles from printheads, which can cause print artifacts and inefficiencies in the ink delivery system.
Innovation Solution
The ink delivery system features a second ink conduit with a smaller internal cross-sectional area than the first conduit, facilitating higher flow speeds and efficient bubble removal, along with a peristaltic pump positioned above the printhead to encourage bubble movement towards the pump and prevent re-entry, and a multi-channel valve arrangement to control ink and air flow, minimizing ink drooling during printhead replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a smaller internal cross-sectional area is used for the second ink conduit, then flow speed increases and bubble removal efficiency improves, but the conduit becomes more prone to blockages and requires higher pumping pressure
Solution Approach 1:
The patent applies different internal cross-sectional areas to different conduits: the first ink conduit has a larger internal cross-sectional area for reliable ink supply, while the second ink conduit has a smaller internal cross-sectional area specifically in the bubble removal section to increase flow speed and enhance bubble entrainment, thus applying local quality differentiation to optimize both reliability and productivity
Solution Approach 2:
The patent changes the physical parameter of internal cross-sectional area of the second ink conduit to optimize flow characteristics. By reducing the internal cross-sectional area, the flow speed increases, which improves bubble removal efficiency through enhanced entrainment, while the system manages the trade-off through pump positioning and pressure control
2Productivity
If the pump is positioned above the printhead, then bubble movement towards the pump is encouraged by buoyancy, but ink drooling may occur during printhead replacement
Solution Approach 1:
The patent extracts the harmful effect of ink drooling by positioning the pump above the printhead, which uses buoyancy to move bubbles upward toward the pump. This positioning ensures that bubbles are removed from the system before they can cause drooling, effectively separating the bubble removal function from the ink delivery function
Solution Approach 2:
The pump acts as an intermediary element that mediates between bubble removal and ink delivery. By positioning it above the printhead, the system uses the pump as a buffer zone where bubbles are captured and removed, preventing them from returning to the printhead and causing drooling during replacement operations
3Productivity
If air bubbles are present in the second conduit when the ink container is below the printhead, then natural buoyancy counteracts flow direction, but higher flow speed can overcome this to improve bubble removal
Solution Approach 1:
The patent changes the flow speed parameter in the second ink conduit by using a smaller internal cross-sectional area. This increases the flow velocity to a level that overcomes the opposing buoyancy force of air bubbles, ensuring that bubbles are carried toward the pump rather than rising against the flow, thus improving bubble removal efficiency
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 configuration enhances air bubble purging efficiency, reduces 'wake-up' times, and minimizes ink spillages during printhead replacement, ensuring faster and more reliable printer readiness.
Implementation Method 1
a pump positioned in the second ink conduit... Preferably, the pump is a peristaltic pump positioned in the second conduit
Implementation Method 2
This relatively higher flow speed in the second conduit facilitates removal of trapped bubbles in the second conduit by entrainment of the bubbles in the higher flow speed
Implementation Method 3
Air bubbles are particularly problematic in the second conduit when the ink container is positioned below a height of the printhead. This is because the natural buoyancy of the air bubbles tends to counter the flow direction in the second conduit
Implementation Method 4
Positioning the pump above the height of the printhead advantageously moves bubbles towards the pump in a direction generally corresponding to the natural buoyancy of air bubbles
Data Source
Figure 1
Figure 2~3
AI summary
An inkjet printer includes: a printhead having a first port and a second port; an ink container for supplying ink to the printhead, the ink container comprising a supply port and a return port; a first ink conduit interconnecting the supply port and the first port; a second ink conduit interconnecting the return port and the second port; and a pump configured for pumping ink from the supply port to the return port. The second ink conduit has a smaller internal cross-sectional area than the first ink conduit for providing a faster flow speed of ink in the second ink conduit relative to the first ink conduit when the pump is actuated.