Overprint Trough Vent Holes Direct Ink Mist Away From Media
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Solution Overview
Problem
Conventional image forming apparatuses face issues with ink mist deposition on media and printhead damage due to inadequate media hold-down, leading to image degradation and increased costs from re-printing due to media tearing during cutting.
Innovation Solution
A media hold-down device with a vacuum platen featuring a two-dimensional array of chambers and adjustable negative pressure, along with an overprint trough with vent holes to direct ink mist away from the media, ensuring consistent hold-down pressure and preventing ink mist deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a vacuum platen is used to hold down the media, then the media positioning precision is improved, but ink mist deposits on the media and printhead damage occurs due to inadequate media hold-down
Solution Approach 1:
The vacuum platen is divided into multiple vacuum chambers arranged in an array, allowing different vacuum levels to be applied to different zones. This segmentation enables the cutting zone to have reduced or zero vacuum pressure, preventing ink mist deposition and printhead damage, while other zones maintain sufficient vacuum for media hold-down and positioning precision.
Solution Approach 2:
Different regions of the vacuum platen are assigned different vacuum pressure characteristics. The cutting zone has local quality of reduced or zero vacuum pressure to prevent harmful effects, while surrounding zones maintain high vacuum pressure for precise media positioning. This local differentiation resolves the contradiction between positioning precision and ink mist deposition prevention.
2Reliability
If the media is held down firmly across the entire platen, then the media hold-down is sufficient to prevent printhead contact, but the media tends to pull away and tear during cutting
Solution Approach 1:
The vacuum platen is segmented into multiple chambers that can be independently controlled. During cutting operations, the chamber corresponding to the cutting zone has its vacuum pressure reduced or eliminated, allowing the media to be released in that specific area. This prevents the media from being pulled away and tearing, while other chambers continue to provide firm hold-down for overall reliability.
Solution Approach 2:
The vacuum pressure in different chambers is dynamically adjusted based on the cutting operation. The system transitions from a static full-vacuum state to a dynamic state where vacuum pressure is selectively applied only where needed, allowing the media to be released in the cutting zone and preventing tearing while maintaining hold-down reliability in other areas.
3Stability of the object's composition
If constant vacuum pressure is applied across all chambers, then the media hold-down is consistent, but the pressure is not appropriate for all stages of media advancement and cutting
Solution Approach 1:
The vacuum pressure in each chamber is dynamically controlled based on the operational stage and media position. During media advancement, chambers are activated sequentially as media covers them. During cutting, the cutting zone chamber pressure is reduced or eliminated. This dynamic pressure adaptation maintains stability where needed while providing versatility for different operational requirements.
Solution Approach 2:
The vacuum chambers are activated and deactivated in periodic sequences corresponding to media advancement and cutting cycles. As media advances, chambers are periodically activated; during cutting, the cutting zone chamber is periodically deactivated. This periodic action provides both consistent hold-down during printing and adaptability during cutting operations.
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 enhances image quality by maintaining precise media positioning, reduces re-printing costs by preventing media tearing, and effectively manages ink mist, ensuring high-quality borderless printing without ink residue on the media or printhead.
Implementation Method 1
a recording medium is attracted onto a flat platen under a vacuum suction
Implementation Method 2
air in an enclosed space below the platen is evacuated to the outside to create a negative pressure in the space
Implementation Method 3
An overprint trough has vent holes in the sloping side walls to suction capture ink mists so as to prevent the mists from landing on the backside of the advancing media
Data Source
AI summary
An image forming apparatus includes a reference surface that is partitioned into an array of chambers; an image forming head for forming an image on a media; and a source of negative pressure. The array of chambers is in fluid communication with the source of negative pressure. An overprint trough is positioned neighboring the array of chambers. The overprint trough includes a side wall with a plurality of vent holes to direct airborne ink mist produced by the image forming head away from a back side of the media.