Printhead Support Cavities for Pulse Damping
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Solution Overview
Problem
High-speed pagewidth inkjet printers face challenges in ink supply management, including shock waves and resonant pulses due to stiff ink lines, leading to nozzle flooding and depriming, which affect print quality.
Innovation Solution
The implementation of a printhead with a support structure featuring ink conduits containing cavities with specific edge configurations to inhibit capillary action and incorporate pulse dampers to absorb pressure spikes, ensuring stable ink flow and priming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-speed pagewidth printhead design is used to increase print speed, then productivity is improved, but shock waves and resonant pulses occur in the ink line causing nozzle flooding and depriming
Solution Approach 1:
The patent incorporates compliant elements (elastomeric materials) into the ink line structure beforehand to cushion and absorb shock waves and resonant pulses before they reach the nozzles. This prevents nozzle flooding and depriming that would otherwise occur at high print speeds, allowing the pagewidth printhead design to operate reliably without compromising print quality.
2Strength
If stiff structure is used to define the ink line for structural integrity, then strength is improved, but shock waves and resonant pulses are not dampened leading to nozzle flooding
Solution Approach 1:
The patent uses composite construction for the ink line, combining stiff structural components with compliant elastomeric materials. The stiff portions maintain structural integrity and proper ink line definition, while the elastomeric portions dampen shock waves and resonant pulses. This composite approach allows the ink line to simultaneously achieve structural strength and pulse dampening, preventing nozzle flooding while maintaining print quality at high speeds.
3Productivity
If high flow rate is used to supply ink to pagewidth printhead, then productivity is improved, but abrupt stopping of ink flow creates shock waves exceeding Laplace pressure
Solution Approach 1:
The compliant elastomeric elements are positioned in the ink line upstream of the nozzles to cushion abrupt pressure changes before they reach the nozzle chambers. When high flow rate ink supply is abruptly stopped, these compliant elements absorb the shock wave and prevent pressure from exceeding Laplace pressure, thereby preventing nozzle flooding while allowing high productivity operation during active printing.
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 nozzle flooding and depriming, maintaining print quality by managing ink flow and pressure pulses, even at high speeds.
Implementation Method 1
the transition face being configured to inhibit ink from filling the cavity by capillary action during initial priming of the ink conduit
Implementation Method 2
each ink conduit includes a plurality of cavities distributed along a roof of the ink conduit... to absorb pressure spikes
Data Source
AI summary
A printhead for an inkjet printer is disclosed. The printhead has one or more a printhead integrated circuits (ICs) with an array of nozzles for ejecting ink. A support structure of the printhead supports the printhead ICs. The support structure has ink conduits for supplying the array of nozzles with ink. Each ink conduit includes cavities distributed along a roof of the ink conduit. An opening to each respective cavity has an upstream edge and a downstream edge. The upstream edge contacts the ink before the downstream edge during initial priming of the ink conduits from an ink supply. The upstream edge has a transition face between the ink conduit and the cavity interior. The transition face is configured to inhibit ink from filling the cavity by capillary action during initial priming of the ink conduit. This causes gas to be trapped within the cavity. The gas acts to compress pressure pulses in the ink.