Pagewide Printhead Nozzle Hydration via Tailored Keep-Wet Patterns
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Solution Overview
Problem
Inkjet printers face challenges in maintaining nozzle hydration, particularly in Memjet® printers, which can lead to clogging and reduced print quality due to dehydration, especially in high-speed web printing where maintenance interventions are time-consuming and wasteful, and keep-wet patterns compromise print quality by adding visible dots.
Innovation Solution
A method for generating print data that includes a keep-wet pattern tailored to each ink plane of the printhead, using parameters like position, ink type, print speed, and ambient conditions to minimize nozzle dehydration while reducing the visibility of the keep-wet pattern, by varying the frequency and pattern of droplet ejections across different ink planes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If keep-wet patterns are printed at high frequency to maintain nozzle hydration, then nozzle hydration is improved, but print quality deteriorates due to visible dots
Solution Approach 1:
The patent applies local quality by differentiating the keep-wet pattern frequency and visibility requirements across different ink planes. Each ink plane is assigned a tailored keep-wet pattern frequency based on its specific position, ink type, and dehydration risk, rather than applying a uniform high-frequency pattern across all nozzles. This allows critical nozzles to receive higher hydration while minimizing visible patterns in less critical areas.
Solution Approach 2:
The patent changes parameters such as keep-wet pattern frequency, dot density, and spacing based on multiple input parameters including ink plane position, ink type, print speed, and ambient conditions. By dynamically adjusting these parameters, the system maintains nozzle hydration while optimizing the visibility of keep-wet patterns for each specific operating condition.
2Reliability
If maintenance cycles are performed frequently to unclog nozzles, then nozzle functionality is improved, but productivity deteriorates due to time consumption and ink waste
Solution Approach 1:
The patent implements preliminary action by continuously maintaining nozzle hydration through tailored keep-wet patterns during normal printing operations. This preventive approach ensures nozzles remain functional without requiring frequent reactive maintenance interventions, thereby preserving productivity while ensuring nozzle reliability.
3Reliability
If sub-ejection pulses are used to warm ink and reduce viscosity, then nozzle hydration is improved, but energy consumption increases
Solution Approach 1:
The patent changes the parameters of droplet ejection by varying the frequency and energy of sub-ejection pulses based on multiple input parameters including ink plane position, ink type, print speed, and ambient conditions. This allows the system to apply thermal energy only when and where needed to maintain hydration, rather than continuously heating all nozzles, thereby optimizing energy consumption.
Data Source
AI summary
A method of multi-color printing in a single pass using a fixed pagewide array of monochrome inkjet printheads. The printheads are aligned with each other in a media feed direction and the method includes the steps of: feeding print media along the media feed direction past a first printhead positioned furthest upstream in the array, a third printhead downstream of the first printhead and a second printhead positioned furthest downstream in the array; printing a yellow ink onto the print media using the first printhead; printing a black ink onto the print media using the third printhead; and printing a cyan or magenta ink onto the print media using the second printhead.