Multi-Bar Inkjet Printer Encoder Feedback for Position Compensation
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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, leading to distortions and visible 'stitches' at transitions between bands.
Innovation Solution
The implementation of at least two encoders to determine substrate positions along a first axis, with a compensation module generating individual parameters for each print bar to compensate for positional variations, ensuring accurate ink ejection and register alignment across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple inkjet print bars are used to print large areas, then printing throughput and coverage area are improved, but positioning inaccuracies between print bars cause image defects and distortions
Solution Approach 1:
The system employs encoders to continuously monitor the actual positions of the substrate and print bars during printing operations. This positional feedback is fed to a control system that calculates compensation parameters and adjusts the ink ejection timing for each print bar accordingly, thereby eliminating positioning inaccuracies and image defects while maintaining high productivity with multiple print bars
Solution Approach 2:
The system dynamically changes the ejection timing parameters of ink drops based on real-time positional measurements. By adjusting the temporal parameter (ejection time) of each print bar according to its actual position relative to the substrate, the system compensates for positioning variations and maintains precise image registration across all print bars
2Adaptability or versatility
If the substrate position varies slightly during printing, then flexibility in handling elastic substrates is improved, but image registration accuracy deteriorates due to offsets between different print bars
Solution Approach 1:
Encoders continuously measure the actual substrate position during printing, providing real-time feedback to the control system. This enables dynamic compensation for substrate position variations, allowing the system to handle elastic substrates with varying tension while maintaining precise image registration across all print bars
Solution Approach 2:
The system transitions from static positioning to dynamic compensation by continuously measuring substrate and print bar positions during operation. The control system dynamically adjusts ejection timing parameters in real-time based on measured positional variations, enabling flexible substrate handling without sacrificing image quality
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 significantly reduces image defects by compensating for substrate position variations, ensuring seamless and accurate printing across large areas without overlaps or voids, thereby enhancing printing quality and throughput.
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
Ink drop ejection may be controlled by suitable actuators such as piezoelectric transducers
Data Source
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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 (1 65.1...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).