Fluidic Damping in Printhead Ink Lines
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Solution Overview
Problem
High-speed pagewidth inkjet printers face issues with ink supply and fluid dynamics, leading to shock waves, nozzle flooding, and resonant pulses due to the stiff structure of the ink line, which affects print quality and efficiency.
Innovation Solution
An active fluidic system with a downstream pump, shut-off valve, and LCP molding with air cavities and a weir design to manage ink flow, pressure pulses, and prevent flooding, combined with a capper to maintain nozzle integrity and prevent dehydration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-speed pagewidth printhead printing is used, then print speed is improved, but shock waves and nozzle flooding occur due to abrupt ink flow termination
Solution Approach 1:
The patent introduces a compliant ink line section with elastic memory effect before the ink delivery point. This compliant section acts as a cushion that absorbs and dampens shock waves generated by abrupt ink flow termination at high print speeds, preventing the shock waves from reaching and flooding the nozzles. The elastic memory effect of the compliant material provides continuous damping action throughout the ink line.
Solution Approach 2:
The patent changes the physical parameters of the ink line by introducing a compliant section with different elastic properties compared to the rigid ink line. This parameter change allows the ink line to flex and absorb pressure spikes, transforming the system from completely rigid to having controlled compliance that prevents nozzle flooding while maintaining high-speed printing capability.
2Manufacturing precision
If stiff ink line structure is used, then manufacturing precision is improved, but resonant pulses occur that cause nozzle flooding or deprime
Solution Approach 1:
The patent applies local quality by having different sections of the ink line with different properties: most of the ink line remains rigid for manufacturing precision and structural integrity, while a specific local section is made compliant with elastic memory effect to dampen resonant pulses. This localized compliance prevents resonant pulse propagation to the nozzles without compromising the overall structural rigidity of the printhead.
Solution Approach 2:
The compliant ink line section is positioned upstream in the ink delivery path to provide beforehand cushioning against resonant pulses generated by simultaneous nozzle firing. This cushioning section absorbs and dampens pressure spikes before they can propagate through the rigid ink line structure and cause nozzle flooding or deprime.
3Productivity
If high ink flow rate is used, then productivity is improved, but shock waves exceed Laplace pressure and flood nozzles
Solution Approach 1:
The patent changes the pressure dynamics parameter by introducing a compliant ink line section that can expand and contract. This allows the system to maintain high ink flow rates for productivity while the compliant section absorbs pressure spikes, preventing shock wave pressure from exceeding the Laplace pressure at the nozzle openings that would cause flooding.
Solution Approach 2:
The compliant ink line with elastic memory effect provides beforehand cushioning that absorbs and dampens shock waves generated by high-velocity ink flow abrupt termination. This cushioning action prevents the shock wave pressure from building up to levels that would exceed the Laplace pressure and flood the nozzles, enabling sustained high flow rate operation.
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
The solution effectively manages ink flow, prevents nozzle flooding, and maintains print quality by absorbing pressure spikes and ensuring consistent ink supply, enhancing the operational reliability and speed of pagewidth printheads.
Implementation Method 1
The LCP molding 64 incorporates a pulse damper to remove pressure spikes from the ink line. The damper may be an enclosed volume of gas that can be compressed by the ink.
Implementation Method 2
The LCP molding 64 incorporates a pulse damper to remove pressure spikes from the ink line... Any pressure pulses in the ink in the main channels 184 act directly on the air in the cavities 200 and quickly dissipate.
Implementation Method 3
The printer also incorporates a pump in the ink supply line downstream of the LCP molding. The pump is controllable to dispense ink at a variety of flow rates.
Implementation Method 4
The pump can be controlled to dispense ink at a variety of flow rates or the pump can be stopped and a valve can be closed off to stop the flow of ink.
Implementation Method 5
The Laplace pressure (the pressure provided by the surface tension of the ink at the nozzles openings to retain ink in the nozzle chambers)
Data Source
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AI summary
A printhead for an inkjet printer that has a printhead integrated circuit (68) with nozzles for ejecting ink, and a support structure (64, 176, 108) for supporting the printhead IC. The support structure has ink conduits (182) for supplying the nozzles with ink and a fluidic damper (200) containing gas for compression by pressure pulses in the ink within the ink conduits to dissipate the pressure pulse. Damping pressure pulses using gas compression can be achieved with small volumes of gas. This preserves a compact design while avoiding any nozzle flooding from transient spikes in the ink pressure.