Line-Scan Surface Inspection with Multi-Angle Lighting for Curved Parts
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Solution Overview
Problem
Conventional surface inspection systems struggle to accurately inspect curved surfaces due to glare phenomena and are limited in detecting defects on models with various shapes, especially when glare occurs, and they fail to control illumination directions and amounts effectively.
Innovation Solution
A non-Lambertian surface inspection system using a line scan camera with multiple illumination modules that emit light at various angles, controlled by a controller to generate composite images, including albedo, partial differential, and normal vector images, while reducing glare and enhancing defect detection on curved surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple illumination method is used, then the system structure is simple and cost is low, but the system can only inspect limited types of defects and cannot handle curved surfaces
Solution Approach 1:
The illumination system is segmented into multiple independent illumination modules (first illumination module, second illumination module, third illumination module, fourth illumination module) positioned at different locations around the inspection object. Each module can be independently controlled to emit light in different directions, allowing the system to handle various surface shapes and defect types while maintaining a modular, manageable structure
Solution Approach 2:
The illumination system is designed with multi-functional capability to inspect various types of defects (black defects, scratches, flaws) on different surface shapes (flat and curved surfaces) using the same system configuration. The multiple illumination modules can be selectively activated to adapt to different inspection requirements, providing universal defect detection capability
2Ease of operation
If conventional illumination control is used, then the system is easy to operate, but glare phenomenon occurs on curved surfaces preventing accurate inspection
Solution Approach 1:
The illumination system dynamically activates different illumination modules based on the surface geometry being inspected. For curved surfaces, the system selectively turns on specific modules (e.g., first and second illumination modules for left and right curved surfaces) to optimize lighting angles and eliminate glare, while maintaining simple operational control through automated module selection
Solution Approach 2:
Different regions of the inspection object receive customized illumination from specific modules positioned to optimize lighting for that local area. The system applies local quality control by directing light from specific modules (first, second, third, or fourth) to different surface regions, ensuring each area is illuminated at optimal angles to prevent glare while maintaining ease of operation
3Reliability
If multiple illumination modules are used, then defect detection capability is improved, but device complexity increases
Solution Approach 1:
The illumination system is divided into four independent modules positioned at different locations, each capable of being independently controlled. This segmentation allows the system to achieve reliable defect detection across various surface types while keeping each module relatively simple in design, making the overall system manageable despite having multiple components
Solution Approach 2:
The system uses selective activation of illumination modules rather than always using all four modules simultaneously. Depending on the inspection object and surface geometry, only the necessary modules are activated (e.g., using only first and second modules for certain curved surface inspections), reducing the effective complexity while maintaining detection reliability
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 effectively reduces glare and enhances defect detection on curved surfaces by controlling illumination angles, allowing for accurate detection of defects like black contamination and scratches, improving inspection efficiency and reliability.
Implementation Method 1
a light-transmission plate installed in the photographing hole and provided with a dot pattern formed on the upper surface thereof and configured to reflect a light downward
Implementation Method 2
a plurality of auxiliary illumination modules installed on sides of the light-transmission plate to emit the light to inside the light-transmission plate
Implementation Method 3
a plurality of first and second illumination modules installed in the curved mounting hole and output light in oblique lines toward an inspection object placed on a bottom surface thereof
Data Source
Figure 1
Figure 2~3
Figure 4~5(c)
AI summary
A non-Lambertian surface inspection system for line scan is proposed. Such a system includes: a surface inspection part including a frame module provided with a curved mounting hole formed on at least one of one surface and the other surface thereof and a photographing hole formed at an upper end thereof, and a plurality of first and second illumination modules installed in the mounting hole and output light in oblique lines toward an inspection object placed on a bottom surface thereof; a camera part positioned above the photographing hole, and configured to photograph the inspection object positioned on the bottom surface through the photographing hole and receive an entire reception image including first and second illumination images; and a controller configured to control operation of the camera part, selectively operate the first illumination module and the second illumination module, and extract the first illumination image and the second illumination image.