Full-Width Printhead Array for Large Inkjet Printers
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Solution Overview
Problem
Large-scale inkjet printers face challenges in maintaining accurate movement of substrates over long distances and suffer from image quality issues due to banding artifacts caused by multi-pass printing techniques, which can lead to inefficiencies and reduced print quality.
Innovation Solution
A multipass large format flat bed inkjet printer design where the printhead array is arranged to cover the full width of the image, allowing for image building in layers rather than swathes, with minimal indexing of the printheads and the use of modular printhead modules for easier alignment and maintenance, along with a curing device that spans the full width for uniform gloss control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multi-pass printing is used to build up the image, then tolerance to defective nozzles is improved, but banding artifacts appear and print quality deteriorates
Solution Approach 1:
The print array is divided into multiple independently controllable printhead modules, each covering a specific width portion. This segmentation allows selective operation of individual modules or groups of modules, enabling defective nozzles to be bypassed while maintaining continuous printing coverage without banding artifacts.
Solution Approach 2:
The invention transitions from traditional single-direction multi-pass printing to a two-dimensional printing approach where multiple printhead modules print simultaneously across the full width of the substrate. This dimensional change eliminates the need for repeated passes over the same areas, thereby preventing banding artifacts while maintaining tolerance to defective nozzles through spatial redundancy.
2Productivity
If the printhead array covers the full width of the image, then the number of print passes is reduced and productivity increases, but the complexity of aligning and maintaining the large printhead array increases
Solution Approach 1:
The large printhead array is segmented into multiple modular units that can be independently positioned and aligned. Each module covers a specific width portion and can be calibrated separately, simplifying the alignment process compared to positioning a single large array. The modular design allows for easier maintenance and replacement of individual modules without affecting the entire system.
Solution Approach 2:
The printhead modules are designed with universal interfaces and standardized mounting mechanisms that simplify alignment and installation. The modules can be universally applied across different printer configurations and can perform multiple functions including printing, monitoring, and self-diagnosis, reducing overall system complexity despite the large coverage area.
3Manufacturing precision
If smaller index distances are used between print passes, then banding effects are reduced, but the number of print passes increases and productivity decreases
Solution Approach 1:
The invention eliminates the need for repeated indexing in the print direction by implementing simultaneous full-width printing across multiple printhead modules. This dimensional transition from sequential multi-pass printing to parallel single-pass printing across the width dimension completely eliminates banding artifacts while maintaining high productivity, as each module prints its designated portion without requiring repositioning.
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 approach eliminates banding artifacts, enhances print quality, increases productivity by reducing the number of print passes, and simplifies the alignment and maintenance of large printhead arrays, while allowing for precise control of gloss levels across the image.
Implementation Method 1
drop-on-demand ink jet printers, in particular piezoelectric ink jet printers
Implementation Method 2
a curing device that spans the full width for uniform gloss control
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
A multipass large format flat bed inkjet printer (1 ) for printing an image on a substrate is described. In examples described, the printer (1 ) has a print carriage (8) for supporting an array of printheads (18) adjacent the substrate (6) during printing; a bed (4) for supporting the substrate (6) during printing; and a movement mechanism (5) for providing relative movement of the print carriage (8) and the substrate (6) in a print direction during a print pass. The print carriage (8) is such that the width of the array of printheads (18) transverse to the print direction is at least substantially the full width of the image. In examples described, the printheads (18) provide an array of nozzles (22) which is substantially continuous across the array of printheads (18).