Air-Knife Aerosol Extractor to Prevent Inkjet Media Strikes
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Solution Overview
Problem
Conventional aerosol extraction systems in inkjet printing systems suffer from issues such as media strikes, reduced effectiveness due to nozzle blockages, and print quality defects, particularly when suction nozzles are placed close to the media path and subjected to increased suction.
Innovation Solution
An aerosol extractor utilizing an air knife and suction nozzle configuration that leverages the Coanda effect to disrupt and lift aerosol away from the media surface, allowing for effective extraction at a distance, with a wide suction slot and adjustable airflow speeds to minimize blockages and media strikes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If suction nozzles are placed close to the media path to extract ink aerosol effectively, then aerosol extraction efficiency is improved, but the risk of media strikes increases causing print quality reduction and system downtime
Solution Approach 1:
The patent introduces a lateral airflow dimension by positioning the air knife adjacent to the media path and directing airflow perpendicular to media travel direction. This creates a three-dimensional aerosol capture zone that combines lateral airflow with downstream suction, allowing effective aerosol extraction without placing suction nozzles in direct contact with the media path, thereby reducing media strike risk while maintaining extraction efficiency
2Productivity
If increased suction is applied to suction nozzles to improve aerosol extraction, then aerosol removal effectiveness is improved, but dehydration of inkjet nozzles increases and excessive airflow causes print quality defects
Solution Approach 1:
The patent extracts aerosol from the boundary layer using a combination of lateral air knife airflow and downstream suction, rather than relying solely on high-intensity suction at the media path. This distributed extraction approach achieves effective aerosol removal with lower suction intensity, preventing inkjet nozzle dehydration and avoiding excessive airflow that would cause print quality defects
Solution Approach 2:
The air knife acts as an intermediary device that pre-disrupts the aerosol boundary layer laterally before the suction nozzle captures the aerosol. This two-stage process using moderate suction intensity combined with lateral airflow achieves effective aerosol extraction without the need for high suction forces that would dehydrate inkjet nozzles or create excessive airflow interfering with print quality
3Duration of action of moving object
If suction nozzles operate during long print runs, then continuous aerosol extraction is maintained, but nozzles become blocked with dehydrated ink and paper dust reducing effectiveness
Solution Approach 1:
The patent creates a wide airflow zone using the air knife that distributes aerosol capture across a broader area. This distributed capture system with multiple entry points into the suction nozzle reduces the likelihood of any single location becoming blocked with dehydrated ink or paper dust, maintaining reliable operation during extended print runs
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
The system achieves efficient aerosol extraction with reduced risk of media strikes and blockages, maintaining print quality by directing aerosol into a suction nozzle, even at varying stand-off heights and print speeds.
Implementation Method 1
An aerosol extractor utilizing an air knife and suction nozzle configuration that leverages the Coanda effect to disrupt and lift aerosol away from the media surface
Implementation Method 2
directing disrupted aerosol into the suction nozzle for extraction
Data Source
Figure 1~2
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Figure 5~6
AI summary
An inkjet printing system includes: a printhead (2) positioned over a media feed path; and an aerosol extractor (10) positioned downstream of the printhead relative to a media feed direction. The aerosol extractor includes: an air knife (12) having a knife slot for directing a flow of air towards print media; and a suction nozzle (16) positioned upstream of the knife slot for directing aerosol into a suction channel.