Printer Stepped Media Path Printhead Alignment
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Solution Overview
Problem
High-speed inkjet printing requires accurate media handling, especially in wide print zones, where existing vacuum belt mechanisms are prone to ink fouling and complex roller systems lead to alignment issues at high speeds.
Innovation Solution
A printer design with a stepped media path using a first and second platen positioned in a downward trajectory, minimizing the distance between overlapping printheads, and employing a simplified intermediary roller assembly to stabilize media handling and reduce alignment problems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If vacuum belt mechanisms are used to transport media through the print zone, then media transport is achieved, but the belt becomes fouled with ink during printing
Solution Approach 1:
The patent removes the vacuum belt from the system entirely, replacing it with a vacuum platen that remains stationary. This extracts the harmful transporting function from the printing system, allowing media to be fed mechanically while the print zone remains stationary and clean, eliminating ink fouling of the transport mechanism
Solution Approach 2:
The patent introduces an intermediary feed mechanism with rollers that transfers media to the stationary vacuum platen. This intermediary system handles the transport function separately from the printing function, allowing the platen to remain clean while still achieving secure media holding through vacuum
2Measurement precision
If complex roller assemblies are used between platens to raise media sheets, then media positioning is achieved, but the distance between printheads increases causing alignment problems
Solution Approach 1:
The patent positions both platens at the same vertical level, creating an equipotential arrangement that eliminates the need for complex roller assemblies to raise or lower media between print zones. Media sheets remain horizontally aligned throughout the printing process, maintaining precision without adding mechanical complexity
Solution Approach 2:
The patent combines the media support and positioning functions into a single horizontal feed path with co-planar platens. This merging of functions eliminates the need for separate elevation mechanisms, reducing device complexity while maintaining positioning accuracy through the simplified roller assembly design
3Area of stationary object
If printheads are arranged in staggered overlapping array to create wide print zones, then print zone width increases, but the distance between printheads increases leading to alignment issues at high speeds
Solution Approach 1:
The patent transitions from a vertical stacking arrangement of printheads to a horizontal array configuration. By arranging printheads side-by-side in the horizontal dimension rather than stacking them vertically, the system achieves wide print zones while maintaining minimal distance between printheads in the media feed direction, ensuring alignment precision at high speeds
Solution Approach 2:
The patent employs an asymmetric staggered overlapping array where adjacent printheads are offset horizontally by half their width. This asymmetric arrangement creates continuous wide print coverage while keeping the vertical spacing between printhead arrays minimal, resolving the conflict between print zone width and alignment precision
Data Source
AI summary
A printer includes: a first fixed printhead having a respective first print zone; a second fixed printhead positioned downstream of the first printhead relative to a media feed direction, the second printhead having a respective second print zone; an input roller assembly positioned upstream of the first platen, the input roller assembly being configured for feeding media sheets along a downward trajectory towards the first print zone; and an intermediary roller assembly positioned between the first and second print zones, the intermediary roller assembly being configured for receiving the media sheets from the first print zone and feeding the media sheets along a downward trajectory. The second print zone is positioned relatively lower than the first print zone.