Refractive Defect Detection in Glass Containers Using Phase Image Analysis
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Solution Overview
Problem
Existing methods for in-line inspection of transparent or translucent containers fail to reliably detect refractive defects and material distribution uniformity, especially when containers are moving at high speeds and have non-uniform glass distribution, leading to difficulties in distinguishing between refractive defects and irregularities in wall thickness.
Innovation Solution
A method involving periodic light intensity variation along specific directions, capturing multiple images of containers as they move, applying geometrical transformations to align pixels, constructing phase and intensity images, and analyzing these images to detect refractive defects and material distribution quality, regardless of container speed or glass uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional point measurements of glass thickness are used, then the inspection process is simple, but the ability to detect refractive defects and assess material distribution uniformity is insufficient
Solution Approach 1:
The patent transitions from point measurements to area measurements by projecting a light pattern through the container wall and capturing the transmitted light distribution across a two-dimensional area. This dimensional change enables simultaneous detection of refractive defects and assessment of material distribution uniformity throughout the entire inspected region, not just at discrete points.
Solution Approach 2:
The patent utilizes changes in light transmission parameters (intensity distribution, pattern deformation) caused by refractive defects and material distribution variations. By analyzing these optical parameter changes rather than direct physical measurements, the system achieves high detection precision while maintaining relatively simple device architecture.
2Productivity
If high-speed in-line inspection is implemented, then productivity increases, but the ability to capture sufficient image data for accurate defect detection deteriorates
Solution Approach 1:
The patent performs preliminary actions by projecting the light pattern through the moving container and capturing the transmitted light distribution before the container exits the inspection zone. This allows complete data acquisition for high-speed moving containers, ensuring sufficient image data is captured for accurate defect detection even at high inspection speeds.
Solution Approach 2:
The patent replaces mechanical measurement systems with optical measurement systems. By using light transmission and image capture instead of physical contact measurements, the system achieves both high inspection speed (productivity) and high detection accuracy simultaneously, as optical methods are non-contact and can operate at the speed of light.
3Adaptability or versatility
If containers with non-uniform glass distribution are inspected, then real-world production conditions are reflected, but the ability to distinguish refractive defects from thickness irregularities deteriorates
Solution Approach 1:
The patent segments the analysis into two distinct components: (1) the overall light transmission pattern that reflects material distribution uniformity, and (2) local deformations or anomalies in the pattern that indicate refractive defects. By separating these analyses, the system can accommodate non-uniform glass distribution while still detecting defects with high precision.
Solution Approach 2:
The patent applies local quality analysis by examining local deformations in the transmitted light pattern to identify refractive defects, while simultaneously assessing the overall material distribution uniformity. This localized analysis approach enables defect detection even when the container has inherent non-uniform glass distribution, as the local defect signatures remain distinguishable from the global non-uniformity pattern.
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
Enables reliable detection of refractive defects and material distribution characteristics in transparent or translucent containers moving at high speeds, effectively distinguishing between refractive defects and irregularities, even with non-uniform glass distribution, by utilizing phase and intensity image analysis.
Implementation Method 1
defects of the crease, orange peel, whittle mark, crinkling, . . . types. In the description below, such defects are referred to as refractive defects or refraction defects.
Data Source
AI summary
An in-line method for optically inspecting transparent or translucent containers (3) comprises illuminating each container with a light source that presents light intensity variation in a periodic pattern along at least a first variation direction. A number N greater than or equal to three of images of the container traveling in front of the light source and occupying N different respective positions along the travel path is taken. Between taking successive images, a relative shift between the container and the periodic pattern is created. A geometrical transformation is determined and applied in order to put the pixels belonging to the container in the N successive images of the same container into coincidence. A phase image for each container is constructed using the N registered images of the container. The phase image is analyzed in order to deduce therefrom at least the presence of defects or the quality of the container.