Rotatable Gantry Printing Assembly for Skew Compensation
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Solution Overview
Problem
Existing printing assemblies face challenges in accurately positioning and rotating print heads for wide-format web printing, leading to misalignment and increased costs due to the complexity of controlling flexible recording mediums and guiding rollers, especially when dealing with anisotropic materials and large formats.
Innovation Solution
A printing assembly with a rotatable gantry that adjusts the scanning direction relative to the medium transport direction, combined with edge detection systems and adaptable guiding rollers, allows for compensation of misalignment and skew errors, enabling versatile and productive printing on wide-format webs by rotating the gantry and repositioning guiding rollers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a page-wide print head is used for wide-format printing, then the positional control is simplified, but the cost increases exponentially and rotational errors are amplified
Solution Approach 1:
The printing system divides the wide-format printing task into multiple scanning passes with a narrower print head. Instead of using one expensive page-wide print head, the system segments the printing process into multiple sequential operations, each using a more affordable, compact print head that scans across the medium in steps.
Solution Approach 2:
The patent introduces dynamic rotation capability to the print head carriage, allowing it to adapt its orientation during operation. This dynamic adjustment enables the system to compensate for medium skew and rotational errors through active control, replacing the need for an overly complex static page-wide print head arrangement.
2Productivity
If the recording medium is step-wise advanced, then productivity is improved, but misalignment of adjacent swaths occurs due to positioning errors
Solution Approach 1:
The system incorporates feedback mechanisms that continuously monitor the position and orientation of the recording medium during step-wise advancement. This feedback enables real-time adjustments to the print head positioning and scanning parameters, compensating for misalignment errors and ensuring accurate swath placement despite the stepped feeding process.
Solution Approach 2:
The patent employs dynamic adjustment of the print head carriage orientation and positioning during the printing process. As the medium is advanced step-wise, the system dynamically modifies scanning parameters and head position to maintain precise alignment between adjacent swaths, transforming a static positioning problem into a dynamically controlled process.
3Adaptability or versatility
If the print head is arranged on a scanning carriage, then flexibility for different media types is improved, but accurate control of print head position becomes more challenging
Solution Approach 1:
The scanning carriage design provides universal applicability across different media types while incorporating integrated control systems. The carriage is designed to accommodate various print head configurations and media widths, and includes built-in sensors and actuators that automatically adapt to the specific medium being printed on, reducing the need for complex external control systems.
Solution Approach 2:
The print head carriage incorporates self-positioning capabilities through integrated sensors and control mechanisms. The system automatically detects medium properties and adjusts its positioning and scanning parameters without requiring complex external intervention, enabling the carriage to serve itself in maintaining accurate position control across different media types.
4Speed
If guiding rollers are used to control the web, then medium transport is enabled, but rotational errors and misalignment increase due to flexibility in the web
Solution Approach 1:
The system employs dynamic compensation mechanisms that actively counteract the effects of web flexibility and roller-induced errors. During medium transport, the print head carriage and scanning system dynamically adjust their positioning and orientation in real-time to compensate for alignment deviations caused by web flexing and roller variations, maintaining precision despite the inherently flexible medium.
Solution Approach 2:
Feedback sensors monitor the actual position and orientation of the recording medium during transport through the guiding rollers. This information is fed back to the control system, which continuously adjusts the scanning parameters and print head positioning to compensate for alignment errors introduced by the roller system and web flexibility, ensuring accurate swath placement.
Data Source
Figure 1A~1B
Figure 2A~2D
Figure 3A~5A
AI summary
In a printer assembly for image-wise providing a recording substance on a recording medium, the printer assembly comprises a print surface for supporting the recording medium; a gantry supporting a print head; and a medium supply assembly for step-wise supplying the recording medium over the print surface in a medium transport direction. The print head is configured to provide a swath of the recording substance on the recording medium arranged on the print surface in a scanning direction. The gantry is rotatable in a plane substantially parallel to the print surface such that the scanning direction is rotatable relative to the medium transport direction. Thus, skewing of the recording medium may be compensated such to prevent visibility of banding due to misalignment of subsequently printed swaths.