3D Height Map Defect Classification for Printing Sheets
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Solution Overview
Problem
Current defect detection systems in printing systems, such as inkjet printing systems, face challenges in accurately identifying and classifying various deformations in sheets, leading to incorrect designation of sheets as suitable or unsuitable for printing, and fail to efficiently determine the root cause of issues due to multiple sources of defects and environmental changes.
Innovation Solution
A defect detection apparatus comprising a sensor device for generating a 3D height map of the sheet surface and a processor device for analyzing and classifying deformations into predefined classes, allowing for real-time determination of sheet suitability for printing and identification of root causes through data analysis and comparison with stored reference criteria.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-type defect detector is used, then the device complexity is reduced, but the measurement precision and reliability of defect detection deteriorates
Solution Approach 1:
The patent combines multiple single-type defect detectors into a single integrated multi-type defect detection device. The sensor device includes multiple sensing elements that can simultaneously detect different types of defects (wrinkles, dog ears, tears, foreign objects) on the sheet, resolving the contradiction by merging multiple detection functions into one unified system that maintains high measurement precision while managing device complexity.
Solution Approach 2:
The defect detection device is designed with multi-functionality to detect various types of defects using a single integrated system. The sensor device can identify different defect types (surface deformations, edge deformations, foreign objects) through multiple sensing mechanisms, making the device universal and eliminating the need for separate single-type detectors for each defect category.
2Reliability
If multiple defect types are detected and classified, then the reliability of defect identification improves, but the device complexity increases
Solution Approach 1:
The patent segments the defect detection process into distinct functional components: sensor devices for detecting different defect types, a processor for analyzing sensor data, and a classification module for categorizing defects. This segmentation allows the system to reliably identify multiple defect types while managing complexity through modular architecture, where each component has a specific function.
Solution Approach 2:
The processor acts as an intermediary between the sensor devices and the control system. It receives raw sensor data, processes and analyzes the information to identify different defect types, and transmits classified defect information to the control system. This intermediary role simplifies the overall system complexity by centralizing the complex analysis function in the processor while keeping other components relatively simple.
3Reliability
If sheets are rejected based on detected defects, then the print quality reliability improves, but the productivity of the printing system deteriorates
Solution Approach 1:
The defect detection device performs preliminary detection and classification of defects on sheets before they enter the printing process. By identifying and rejecting defective sheets in advance, the system prevents print quality issues without causing delays during the actual printing operation. This preliminary action ensures that only suitable sheets are printed, maintaining high print quality reliability while minimizing impact on overall productivity.
Solution Approach 2:
The system implements feedback control where the defect detection device continuously monitors sheets and provides real-time information to the control system. The control system uses this feedback to selectively reject only those sheets with defects that would compromise print quality, while allowing defect-free sheets to proceed to printing. This feedback mechanism optimizes the balance between print quality reliability and productivity by making rejection decisions based on actual defect conditions rather than blanket rejection.
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
The system provides accurate and versatile defect detection and classification, enabling timely ejection of unsuitable sheets and optimization of printing conditions, reducing downtime and improving print quality by accurately identifying and addressing deformation causes.
Implementation Method 1
a sensor device for sensing a surface geometry or topology of a sheet to be printed and for generating data that is representative of that surface geometry or topology
Data Source
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AI summary
An apparatus for defect detection in a printing system, comprising a sensor device for sensing a surface of a sheet and for generating data representing a height map of the sheet, and a processor device for processing the data from the sensor device, wherein the processor device is configured to analyse the height map to detect a presence of a deformation in the sheet. The processor device is further configured to, when a deformation is detected, to determine at least one property of the deformation, to classify the deformation with respect to a plurality of deformation classes by means of the at least one property of the deformation, and to determine a suitability of the sheet for printing based on the deformation class wherein the deformation has been classified.