Digital Printing Substrate Alignment via Optical Imaging
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Solution Overview
Problem
Current digital printing systems lack an effective method to detect errors in the position of substrates relative to grippers, which is crucial for accurate image transfer and quality control.
Innovation Solution
A digital printing system that includes an imaging device to capture a digital image of a region of interest associated with the grippers and substrate, using dark-bright transition points to determine the correct alignment between the gripper edge and gripper bottom line, and a controller to compare these points to predefined criteria, triggering actions if alignment errors are detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If no position detection system is used, then the device complexity is reduced, but the manufacturing precision of substrate positioning deteriorates
Solution Approach 1:
The patent replaces complex mechanical position detection mechanisms with an optical imaging system. The imaging device captures images of the substrate and grippers, and the controller processes these images to determine positions and detect misalignment, eliminating the need for mechanical sensors while maintaining high positioning precision.
Solution Approach 2:
The patent uses optical copying by capturing images of the substrate and grippers with an imaging device. The controller processes these optical copies (images) to determine positions and detect misalignment, replacing direct mechanical measurement with optical field copying and digital processing.
2Manufacturing precision
If real-time position detection is implemented, then the manufacturing precision is improved, but the device complexity increases
Solution Approach 1:
The imaging device serves multiple functions: capturing substrate position, capturing gripper position, and providing visual feedback for quality control. The controller processes images to determine both substrate and gripper positions and to detect misalignment, making the system multi-functional rather than requiring separate specialized devices for each function.
Solution Approach 2:
The patent introduces an imaging device as an intermediary between the physical substrate/gripper system and the control system. Instead of direct mechanical contact or complex sensor arrays, the imaging device captures optical information that the controller processes to determine positions and detect misalignment, simplifying the overall system architecture.
3Reliability
If misalignment detection is added, then the reliability of image transfer is improved, but the device complexity increases
Solution Approach 1:
The patent implements feedback by detecting substrate misalignment relative to grippers and providing this information to the control system. The system can then take corrective actions such as adjusting substrate position or gripper timing, creating a closed-loop control system that improves image transfer reliability through continuous monitoring and correction.
Data Source
AI summary
A system and method for performing quality control in a digital printing system (DPS) is provided. The DPS includes an impression station for transferring an ink image from a surface of an intermediate transfer member to a substrate. The impression station includes an impression cylinder housing one or more grippers operable to grasp and hold a leading edge of the substrate as it passes through the DPS, for conveying the substrate along the impression cylinder during the transfer of the ink image. An imaging device is operable, during advancement of the substrate on the impression cylinder, to capture a digital image including a region of interest (ROI) that is associated with at least a portion of the grippers and at least a portion of the substrate. A controller is configured, based on the digital image, to indicate an error in a position of the substrate relative to the grippers.