Inkjet Printhead Nozzle Drying Detection and Humidification Control
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Solution Overview
Problem
Inkjet imaging devices face issues with aqueous inks drying out quickly and ink satellites causing nozzle failures, leading to quality degradation and maintenance challenges, especially when unused inkjets need to be fired to maintain ink flow without affecting image quality.
Innovation Solution
A method and system that detect failing inkjets by forming a test pattern and using an optical sensor to compare image data, with a diffuser emitting humidified air to maintain ink viscosity and prevent nozzle drying, allowing inkjets to be restored without purging or maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If unused inkjets are fired to maintain ink flow and prevent drying, then ink viscosity is maintained and nozzles remain operational, but extraneous ink is deposited on the media affecting image quality
Solution Approach 1:
The patent divides the inkjet array into actively used inkjets and unused inkjets. The unused inkjets are selectively fired at reduced frequency compared to active inkjets, allowing maintenance of ink flow in unused nozzles without depositing excessive ink on the media. This segmentation enables differential operation based on usage requirements.
Solution Approach 2:
The patent applies partial action by firing unused inkjets at a frequency lower than fully active inkjets but higher than complete idle state. This partial firing maintains sufficient ink flow to prevent drying and clogging while minimizing extraneous ink deposition that would degrade image quality.
2Manufacturing precision
If aqueous inks are used for printing, then image quality and color variety are improved, but inks dry out quickly in unused inkjets during printing operations
Solution Approach 1:
The patent implements periodic action by firing unused inkjets at intervals during printing operations. This periodic firing maintains ink flow and prevents the aqueous ink from drying out in unused nozzles, while allowing the majority of printing operations to proceed with high-quality image formation.
Solution Approach 2:
The patent changes the operational parameters of unused inkjets by reducing firing frequency compared to active inkjets. This parameter adjustment maintains ink流动性 in unused nozzles preventing drying, while the reduced firing rate minimizes impact on overall printing efficiency and image quality.
3Manufacturing precision
If ink satellites are allowed to land near inkjet nozzles during printing, then complete ink coverage is achieved, but satellites dry out and cause nozzle failures over time
Solution Approach 1:
The patent uses humidified air as an intermediary environment in the print zone. This humidified atmosphere prevents ink satellites that land near nozzles from drying out, thereby preventing the formation of clogs that would cause nozzle failures, while still allowing complete ink coverage to be achieved.
4Reliability
If a diffuser is used to emit humidified air toward the media, then ink viscosity is maintained and drying is prevented, but device complexity increases
Solution Approach 1:
The patent implements self-service by using the waste heat from the printer's normal operation to humidify the air in the print zone. This approach maintains ink viscosity and prevents drying without requiring a separate, complex humidification system, thereby adding minimal device complexity.
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
Effectively identifies and remedies failing inkjets by maintaining ink flow and preventing nozzle failures, ensuring continuous operation without adverse impact on image quality or requiring extensive maintenance.
Implementation Method 1
operating with the controller a diffuser to direct humidified air toward the media passing the diffuser
Implementation Method 2
generating with an optical sensor image data of the test pattern formed on the media
Data Source
AI summary
A directionality detector is configured for use in an inkjet printer to attenuate the effects of ink drying in the nozzles of a printhead during printing operations. The directionality detector includes an optical sensor that generates image data of a test pattern formed on media by the printer, a diffuser that emits humidified air toward the media before the media is printed, and a controller operatively connected to the optical sensor and diffuser. The controller is configured compare the image data of the test pattern to stored image data of the test pattern printed at a previous time and determine whether any difference between the two images is greater than a predetermined threshold. The controller then operates the diffuser to direct humidified air toward the media passing the diffuser using the differences between the stored image data of the test pattern and the image data of the test pattern.