Alternating Side Illumination for Optical Sorting Inspection
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Solution Overview
Problem
Optical sorting machines face challenges in accurately detecting defects in bulk food products due to varying product velocities and illumination synchronization issues, leading to inconsistent detection accuracy and potential misclassification of good products as defective.
Innovation Solution
The apparatus employs alternating light sources with different wavelength and amplitude ranges on both sides of the product stream, synchronized with rapid activation and adjustment to accommodate varying velocities, using elongated pixels and auxiliary lighting to enhance defect detection and cross-checking between sequential detections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single light source is used for illumination, then the device complexity is reduced, but the measurement precision deteriorates due to inability to detect defects on both sides of products
Solution Approach 1:
The illumination system is segmented into multiple independent light sources positioned at different locations (front, rear, left, right) relative to the product stream. Each light source illuminates a specific viewing zone, enabling comprehensive defect detection on all product surfaces without requiring a single complex illumination system.
Solution Approach 2:
Different light sources are optimized for specific detection purposes: front and rear lights detect defects on respective product ends, while side lights detect surface defects. This local optimization of illumination quality enhances overall measurement precision without uniformly increasing system complexity.
2Productivity
If the light source illuminates continuously, then the reliability of detection is improved, but the productivity deteriorates due to inability to handle high velocity product streams
Solution Approach 1:
The illumination system uses periodic flashing of light sources synchronized with the product flow velocity. Each light source flashes at specific intervals corresponding to the time products pass through its illumination zone, enabling reliable defect detection even at high throughputs. The periodic action maintains detection reliability while accommodating high productivity requirements.
Solution Approach 2:
The illumination system dynamically adjusts the flashing frequency and timing of each light source based on detected product velocity. When products move faster, the flash frequency increases; when slower, it decreases. This dynamic adaptation maintains optimal detection reliability across varying productivity levels.
3Adaptability or versatility
If the illumination is optimized for one wavelength range, then the measurement precision for specific defect types is improved, but the adaptability deteriorates due to inability to detect multiple defect types
Solution Approach 1:
The illumination system employs multiple light sources capable of operating across different wavelength ranges (e.g., UV, visible, IR). Each light source can be independently activated based on the type of defect being detected, providing universal adaptability for multiple defect types while maintaining measurement precision through wavelength-specific optimization.
Solution Approach 2:
The system changes illumination parameters (wavelength, intensity, duration) based on the detected product type and suspected defect characteristics. By dynamically adjusting these parameters, the system maintains high measurement precision across different defect types without requiring separate specialized systems for each defect category.
4Loss of information
If the light flashing frequency is increased to match high product velocities, then the productivity is improved, but the loss of information deteriorates due to reduced exposure time for defect detection
Solution Approach 1:
The system performs preliminary velocity measurement of the product stream before initiating defect detection. Based on this preliminary information, each light source is pre-configured with appropriate flashing frequency and duration to maximize information capture at the detected velocity, preventing information loss while maintaining high productivity.
Solution Approach 2:
The illumination system uses feedback from velocity sensors to continuously adjust the flashing frequency and duration of light sources. This real-time feedback ensures that exposure time is optimized for the current product velocity, capturing sufficient defect information even at high sorting speeds without requiring excessively long exposure times.
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
This approach enables comprehensive inspection and improved detection accuracy by synchronizing illumination with product movement, reducing misclassification and enhancing the ability to identify discolorations and defects across different product velocities, thus optimizing the sorting process.
Implementation Method 1
first light means comprising light emitting diodes for illuminating the viewing station from one side of the stream of product pieces with light reflection from the product pieces; and second light means comprising light emitting diodes for illuminating the viewing station from the other side of the stream with light for reflection from the product pieces
Data Source
AI summary
Apparatus for inspecting product pieces in a product stream comprising a system for creating a stream of product pieces for delivery in free flight at a viewing station, first light means for illuminating the viewing station from one side with light for reflection from product therein, second light means for illuminating the viewing station from the other side with light for reflection from product therein, a scanning system for receiving light from the first and second illuminating means reflected from product pieces in the viewing station and transmitted across the viewing station, and means for activating the first and second light means alternately in first and second scanning phases to successively illuminate a product stream at the viewing station.