Refractive Defect Detection in Moving Containers
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Solution Overview
Problem
Existing methods for inspecting transparent or translucent containers, such as bottles, are inadequate for detecting refractive defects and material distribution quality, especially when containers are moving at high speeds and have heterogeneous glass distributions, leading to difficulties in distinguishing refractive defects from irregularities in the container's thickness.
Innovation Solution
A high-speed online inspection method using a linear camera and a light source with a continuous variation of light intensity in a periodic pattern, where the light source and camera are connected to a control and image processing unit, allowing for the acquisition of successive image lines and phase image calculation to detect refractive defects and material distribution quality, while accounting for container movement and vibration effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a periodic light pattern is used to detect refractive defects, then detection sensitivity is improved, but the ability to distinguish defects from material distribution irregularities deteriorates when containers have heterogeneous glass distributions
Solution Approach 1:
The patent segments the light pattern into multiple independent sinusoidal components with different spatial frequencies. Each frequency component interacts differently with refractive defects versus material distribution irregularities, allowing the system to analyze and distinguish between these two types of variations through frequency-domain decomposition of the captured image patterns.
Solution Approach 2:
The patent applies multiple periodic light patterns with different spatial frequencies beyond what a single pattern would provide. By using a plurality of frequency components, the system obtains redundant and complementary information that enables reliable distinction between refractive defects and material distribution irregularities even when the container has heterogeneous glass distribution.
2Productivity
If high-speed online inspection is implemented, then productivity is improved, but measurement precision deteriorates due to container movement and vibration effects
Solution Approach 1:
The patent performs preliminary calibration to determine the relationship between container position and image coordinates before actual defect detection. This pre-established positional reference allows the system to compensate for container movement and vibration during high-speed inspection, maintaining measurement precision while enabling productive online operation.
Solution Approach 2:
The patent implements feedback mechanisms that use the captured image patterns and known light pattern frequencies to calculate and correct for container position variations. The system continuously adjusts its analysis based on feedback from the actual captured patterns, compensating for movement effects in real-time during high-speed inspection.
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 assessment of material distribution quality in transparent or translucent containers moving at high speeds, improving the accuracy and efficiency of quality control by reducing the impact of container movement and heterogeneous material distributions.
Implementation Method 1
Refractive defects in the container, due to the lensing effect, present portions of the light source to the camera in a compressed form.
Data Source
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AI summary
The invention relates to a method of inspecting containers (3) moving between a linear camera and a light source (7) and exhibiting a continuous variation of luminous intensity according to a periodic pattern (71) along at least one direction of variation (D). According to the invention: for each increment of displacement of the container, a sequence of N Signs of successive images of the container is acquired cyclically, so that for each image line: the container (3) is illuminated by the light source (7), the image line of the container is acquired, the periodic pattern (71) is shifted for the next line along the direction of variation (D), at least one phase image line is calculated for each increment of the container (3), the phase image lines (LP(k)) are analyzed.