Inkjet printer
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Solution Overview
Problem
Inkjet printers with multiple print bars are prone to image defects due to positioning inaccuracies, especially when printing large areas, as slight substrate position variations can lead to distortions and visible 'stitches' between scan bands.
Innovation Solution
The implementation of at least two encoders to determine substrate positions along a first axis, with a compensation module generating individual compensation parameters for each inkjet print bar to adjust ink ejection, ensuring accurate registration and minimizing image errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple inkjet print bars are used to print large areas, then printing coverage and productivity are improved, but positioning inaccuracies cause image defects and registration errors
Solution Approach 1:
The system uses encoders to continuously monitor the actual positions of the substrate and print bars during printing, feeding this information back to a control unit that calculates compensation values. These compensation values are then applied to adjust the ink ejection timing or print bar positions, creating a closed-loop feedback system that actively corrects positioning errors and maintains accurate registration across large printing areas.
Solution Approach 2:
The system dynamically changes operational parameters (such as ink ejection timing, print bar position, or substrate feed rate) based on real-time encoder measurements. By adjusting these parameters in response to detected position variations, the system compensates for positioning inaccuracies and maintains precise image registration even when printing large areas with multiple print bars.
2Ease of operation
If substrate position is allowed to vary slightly during printing, then ease of substrate handling is improved, but image registration and quality deteriorate due to visible stitches and distortions
Solution Approach 1:
Encoders continuously monitor substrate position variations during printing, and the control unit processes this feedback information to calculate real-time compensation values. These compensations adjust the printing parameters to account for substrate movement, allowing flexible substrate handling while maintaining precise image registration and preventing visible stitches or distortions.
Solution Approach 2:
The system transitions from a static printing approach to a dynamic one where compensation parameters are continuously adjusted during the printing process based on real-time substrate position measurements. This dynamic adaptation allows the system to accommodate substrate position variations and maintain high registration accuracy throughout the printing operation.
3Manufacturing precision
If individual compensation parameters are generated for each print bar, then image registration accuracy is improved, but device complexity and computational requirements increase
Solution Approach 1:
The compensation system is segmented by assigning individual compensation parameters to each print bar based on its specific position and characteristics. The control unit processes encoder data separately for each print bar, generating tailored compensation values that account for position-specific variations. This segmentation enables precise registration for each print bar while maintaining overall system manageability.
4Manufacturing precision
If encoders and compensation mechanisms are added to correct position variations, then image quality and registration are improved, but device complexity and cost increase
Solution Approach 1:
The system incorporates encoders that provide real-time position feedback and a control unit that processes this information to generate compensation parameters. This feedback mechanism enables accurate image registration by continuously monitoring and correcting position variations, justifying the added complexity through significant improvements in print quality and registration accuracy.
Solution Approach 2:
The system replaces complex mechanical positioning mechanisms with a more compact electronic solution using encoders and software-based compensation. Instead of adding heavy mechanical adjustment devices, the invention uses electronic sensing and computational compensation to achieve precise registration, reducing overall mechanical complexity while maintaining or improving accuracy.
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 effectively compensates for substrate position variations, reducing image defects and ensuring seamless printing across multiple print bars, thereby enhancing the quality and accuracy of large-area prints.
Implementation Method 1
at least two first encoders for the determination of at least two first positions of substrate locations arranged along the first axis
Implementation Method 2
a compensation module for processing the at least two determined first positions to generate at least one first individual compensation parameter for each of the at least two inkjet print bars
Implementation Method 3
Ink drop ejection may be controlled by suitable actuators such as piezoelectric transducers
Data Source
AI summary
An inkjet printer comprises a transport mechanism (120) for transporting a substrate along a first axis, a print engine (160) comprising at least two inkjet print bars (165.1 . . . 8) arranged along the first axis, and a controller for controlling the ejection of ink by the at least two inkjet print bars. It further comprises at least two first encoders for the determination of at least two first positions of substrate locations along the first axis and a compensation module for processing the at least two determined first positions to generate at least one first individual compensation parameter for each of the at least two inkjet print bars (165.1 . . . 8). The first compensation parameters are transmitted to the controller to influence the ejection of ink in such a way that effects due to variations of the at least two first positions of the substrate along the first axis are compensated. The effects of positioning errors that may affect different print bars (165.1 . . . 8) arranged along the longitudinal axis of the print engine (160) differently may be compensated using the encoders, individually for the different print bars (165.1 . . . 8).