Sacrificial Sheet Steering for Full-Width Inkjet Printhead Maintenance
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Solution Overview
Problem
Inkjet printheads clog when unused for extended periods due to viscous fluid buildup, leading to missing jets, reduced ink ejection, and potential irreversible damage, especially with certain ink colors drying faster than others.
Innovation Solution
The system employs sacrificial sheets and dual edge registration to maintain full-width printhead jetting, using sacrificial sheets to align with both edges of the sheet transport, ensuring all nozzles are periodically jetted, regardless of sheet size, and controlling the inkjet printhead to eject ink from specific nozzles based on usage time or sheet count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a smaller size sheet or short edge feed is used, then sheet size adaptability is improved, but nozzle clogging increases due to extended idle periods of unused jets
Solution Approach 1:
The system divides the sheet transport width into multiple zones and uses multiple sacrificial sheets positioned at different locations. Each sacrificial sheet receives ink from specific nozzle groups, ensuring all nozzles remain active even when printing on smaller sheets. This segmentation allows the system to maintain full nozzle functionality while adapting to various sheet sizes.
Solution Approach 2:
The system performs preliminary jetting actions onto sacrificial sheets before actual printing jobs. By periodically ejecting ink onto sacrificial sheets that are positioned to receive output from all nozzle groups, the system prevents idle nozzles from clogging in advance of potential use, maintaining nozzle reliability across different sheet size configurations.
2Reliability
If print head maintenance processes are run frequently, then nozzle clogging is reduced, but consumable waste increases and productivity decreases
Solution Approach 1:
The system uses sacrificial sheets as self-service maintenance targets. Instead of requiring manual intervention or dedicated maintenance cycles, the printing system automatically directs periodic jetting onto these sacrificial sheets during normal operation, allowing the printhead to self-maintain without stopping production or wasting additional consumables on separate maintenance jobs.
Solution Approach 2:
The system discards sacrificial sheets after they have served their maintenance function, rather than attempting to recover or reuse them. Each sacrificial sheet is used once to receive ink from specific nozzle groups, then discarded, while the nozzles remain functional for subsequent printing jobs. This approach eliminates the need for complex sheet recovery processes.
3Reliability
If all nozzles are jetted continuously, then nozzle clogging is prevented, but ink consumption increases and productivity decreases
Solution Approach 1:
The system applies local quality by directing ink jetting onto different portions of sacrificial sheets based on which nozzle groups need maintenance. Rather than uniformly jetting all nozzles at all times, the system selectively activates specific nozzle groups onto corresponding sacrificial sheet zones, reducing overall ink consumption while maintaining all nozzles functionality.
Solution Approach 2:
The system implements periodic jetting actions onto sacrificial sheets rather than continuous jetting. By timing maintenance jetting to occur during idle periods or between printing jobs, and by using sacrificial sheets to absorb the maintenance ink, the system prevents nozzle clogging without requiring continuous ink ejection that would waste consumables and reduce productivity.
4Reliability
If dual edge registration with multiple sacrificial sheets is implemented, then full width printhead jetting is achieved, but device complexity increases
Solution Approach 1:
The sheet registration device performs multiple functions: it aligns sacrificial sheets for maintenance jetting, positions actual printing sheets for production, and accommodates various sheet sizes. By making the registration system universal rather than dedicated solely to sacrificial sheet handling, the system achieves full width printhead jetting without requiring separate complex mechanisms.
Solution Approach 2:
The system merges the handling of sacrificial sheets and printing sheets into a single sheet transport and registration mechanism. Rather than having separate systems for maintenance and production, the dual edge registration device manages both types of sheets through one integrated system, reducing overall device complexity while maintaining full nozzle functionality.
Data Source
AI summary
Devices and processes include/use an inkjet printhead, a sheet transport positioned to move sheets of media past the inkjet printhead, a sheet registration device positioned to align the sheets of media, and a controller electrically connected to the inkjet printhead and the sheet registration device. The controller is adapted to periodically control the sheet registration device to align a first sacrificial sheet with a first edge of the sheet transport and align a second sacrificial sheet with a second edge of the sheet transport and that is opposite the first edge. The controller is adapted to control the inkjet printhead to eject ink from a first set of nozzles to the first sacrificial sheet and eject ink from a second set of nozzles to the second sacrificial sheet. The first set of nozzles contains different nozzles from the second set of nozzles.