Recirculating Purge Media for Inkjet Printhead Maintenance
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Solution Overview
Problem
Inkjet printers face issues with ink drying and clogging when printing on media sheets narrower than the print zone, leading to operational status problems and image quality defects, as unused inkjets are prone to viscosity changes and evaporation, resulting in inefficiencies and increased costs due to the need for purge sheets.
Innovation Solution
A printer system that incorporates a supply of purge sheets and a controller to strategically insert and recirculate these sheets through the print zone, ensuring all inkjets are maintained in a low viscosity state by repeatedly merging them into the media stream, thereby reducing ink evaporation and preserving operational status.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If purge sheets are inserted into the media stream to maintain inkjet operational status, then inkjet reliability is improved, but media waste increases
Solution Approach 1:
The patent implements a recirculating purge media system where purge sheets are inserted into the media stream to clean unused inkjets, then collected and reused in subsequent print jobs. Instead of discarding purge sheets after single use, the system recovers them from the output tray, stores them in a recirculating purge media stack, and reinserts them into the media stream for continued inkjet maintenance, thereby reducing media waste while maintaining inkjet reliability
Solution Approach 2:
The purge sheets serve multiple functions: they act as cleaning substrates for unused inkjets during periods of inactivity, serve as recyclable media that can be reused across multiple print jobs, and function as a bridge between different print job requirements. The recirculating system allows the same purge sheets to perform inkjet maintenance duties repeatedly across different media types and print jobs
2Reliability
If purge sheets are used to prevent ink drying, then inkjet reliability is improved, but printing productivity decreases
Solution Approach 1:
The system performs inkjet maintenance actions during transitions between print jobs or during idle periods when the printer is not actively processing media. The controller monitors for periods of printhead inactivity and inserts purge sheets into the media stream during these intervals to clean unused inkjets, ensuring that maintenance occurs preliminarily before the next print job begins, thereby minimizing impact on active printing productivity
Solution Approach 2:
The recirculating purge media system operates periodically by inserting purge sheets into the media stream at scheduled intervals during print jobs or between jobs. The controller manages the periodic insertion and recirculation of purge sheets through the duplex path and back into the media stream, providing continuous inkjet maintenance without requiring constant intervention, thus balancing reliability improvement with productivity maintenance
3Reliability
If all inkjets are fired regularly to prevent clogging, then inkjet reliability is improved, but ink consumption increases
Solution Approach 1:
The system applies different treatment strategies to different inkjet groups based on their usage patterns. Unused inkjets (those outside the media width or not selected for the current print job) receive targeted maintenance through purge sheet insertion, while actively used inkjets continue normal operation. This localized approach ensures that maintenance resources are concentrated where needed most, preventing unnecessary ink consumption from firing all inkjets uniformly while still maintaining reliability of all inkjet components
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 approach effectively reduces ink drying and clogs, maintaining the operational status of all inkjets, minimizing waste, and enhancing printing efficiency by using purge sheets to maintain ink viscosity and correct operational issues during job streams.
Implementation Method 1
attenuate the drying of ink from inkjets in a printhead during periods of partial printhead inactivity
Data Source
AI summary
A method of operating a printer repetitively merges a purge sheet into a media stream of a job stream in the printer so the controller of the printer can operate inactive inkjets and eject ink onto the purge sheet to maintain the operational status of the inactive inkjets. The purge sheet has a width that is at least the maximum width of a print zone in the printer in the cross-process direction and a length that is less than a length of any media sheet in the job stream in the process direction. The purge sheet is diverted through a duplex path in the printer to repetitively merge the purge sheet into the media stream of the job stream to maintain the operational status of the inactive inkjets.