Surface Inspection Apparatus Edge Detection
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Solution Overview
Problem
Existing surface inspection technologies face challenges in accurately distinguishing between shape-derived and non-shape-derived unevenness on multi-surface inspection targets, as shadows and light/dark reflections complicate the identification of edges, leading to incorrect detection of defects.
Innovation Solution
A surface inspection apparatus that forms inspection patterns with alternating brightness levels, projects these patterns onto the target, extracts edges, sets correction coefficients to reduce intensity influence, and integrates images to determine unevenness, enabling accurate differentiation between shape-related and non-shape-related surface irregularities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a stripe pattern is projected onto a multi-surface inspection target, then surface unevenness can be detected, but shadow reflections from one surface to another create false edges that complicate defect identification
Solution Approach 1:
The patent divides the inspection process into multiple sequential steps by projecting multiple inspection patterns with different brightness levels. The first inspection pattern (higher brightness) detects bright edges, while the second inspection pattern (lower brightness) detects dark edges. This segmentation allows the system to separately identify and process different types of edges, reducing interference from shadow reflections.
Solution Approach 2:
The patent applies different brightness levels to different regions of the inspection pattern. By using a first inspection pattern with higher brightness for detecting bright edges and a second inspection pattern with lower brightness for detecting dark edges, the system optimizes the local quality of light interaction with different surface features, enabling accurate differentiation between shape-derived edges and defect-induced edges.
2Measurement precision
If edges are detected by connecting pixels with brightness values above a threshold, then both shape boundaries and surface defects are detected, but the two types of edges cannot be easily distinguished
Solution Approach 1:
The patent segments edge detection into two distinct processes: detecting bright edges using a first inspection pattern with higher brightness, and detecting dark edges using a second inspection pattern with lower brightness. This segmentation preserves information about edge type (bright vs. dark) that would otherwise be lost in conventional single-threshold detection, enabling the system to differentiate between shape boundaries and surface defects.
Solution Approach 2:
The patent uses brightness variations (analogous to color changes) to encode different types of edge information. By projecting inspection patterns with different brightness levels and detecting the resulting bright and dark edges separately, the system maintains information about the nature of each edge, allowing differentiation between shape-derived edges and defect-induced edges.
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 solution effectively reduces the influence of shape-derived edges and enhances the detection of non-shape-derived unevenness, allowing for precise inspection and differentiation, thereby improving the accuracy of surface defect identification.
Implementation Method 1
a captured image acquiring unit configured to acquire a captured image of the inspection target object each time the inspection pattern is projected
Data Source
AI summary
A surface inspection apparatus includes: an inspection pattern forming unit that forms inspection patterns; a projection unit that projects the inspection patterns onto an inspection target object; a captured image acquiring unit that acquires captured images of the inspection target object; an edge extraction image creating unit that extracts edges from captured images, and creates edge extraction images; a correction coefficient setting unit that sets a correction coefficient for correcting intensities of edges in the edge extraction image; an intensity correcting unit that corrects the intensities of the edges; a corrected edge extraction image creating unit that creates corrected edge extraction images; an integrated image creating unit that creates a single integrated image by integrating the brightness values at the same position of the inspection target object; and a determination unit that determines the presence or absence of unevenness on a surface of the inspection target object.