Diffuse Illumination for Article Inspection Systems
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Solution Overview
Problem
Existing article inspection systems face challenges with uneven illumination, particularly in fruit sorting, due to the limitations of polarized direct illumination and the sensitivity of diffuse illumination to geometric variations, leading to image artefacts and reduced accuracy in sorting.
Innovation Solution
The implementation of an article inspection system with elongate lane dividers housing light diffusers positioned adjacent to conveyor paths to provide diffuse illumination, ensuring even light distribution across the sides and surfaces of articles, combined with upper light sources for uniform illumination, and a light intensity controller to maintain consistent lighting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If polarised direct illumination is used to illuminate articles, then specular reflection is removed from images, but polarising material is costly and cuts out a high proportion of incident light reducing image quality
Solution Approach 1:
The patent extracts and removes the polarising material from the illumination system, replacing it with a diffuser that eliminates the need for polarisers while maintaining the ability to capture diffuse reflections without specular interference
Solution Approach 2:
The patent introduces a diffuser as an intermediary element between the light source and the article, which scatters light to create diffuse illumination that naturally eliminates specular reflections without requiring polarising filters
2Device complexity
If polarised direct illumination with discrete light sources is used, then illumination structure is simplified, but shadows and image artefacts are produced across article inspection scenes
Solution Approach 1:
The diffuser acts as an intermediary that transforms discrete light sources into a continuous diffuse illumination field, eliminating shadows and artefacts while keeping the discrete source structure simple
Solution Approach 2:
The patent changes the illumination parameter from direct discrete beams to diffuse distributed light by introducing the diffuser, which transforms the light distribution pattern to eliminate shadows
3Ease of manufacture
If diffused illumination is used to illuminate articles, then polarisers are not required reducing cost, but geometric variations of inspected articles produce specular reflection that hides useful diffused reflection
Solution Approach 1:
The diffuser positioned at or below article level acts as an intermediary that provides diffuse illumination from the side, creating a geometry where specular reflections are directed away from the camera while diffuse reflections remain visible
Solution Approach 2:
The patent applies local quality by positioning the diffuser specifically at or below article level rather than above, creating localized illumination geometry that addresses the specular reflection problem for side-view imaging
4Device complexity
If diffused illumination is used in a translating conveyor system, then illumination setup is simplified, but variance of Fresnel reflections creates different illumination conditions for different camera views and positions
Solution Approach 1:
The patent segments the illumination system into multiple diffusers positioned at different locations along the conveyor path, ensuring each segment provides consistent diffuse illumination for its corresponding camera view and position
Solution Approach 2:
The patent changes the illumination parameter distribution by positioning multiple diffusers at specific locations to compensate for the translating motion, maintaining consistent illumination conditions across different positions and views
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 configuration enhances image quality and accuracy in sorting by reducing image artefacts and maintaining consistent illumination across varying article geometries and conveyor positions, outperforming previous systems in terms of radial uniformity and overall performance.
Implementation Method 1
illuminate, using light from the one or more light sources, at least side portions of the articles with substantially diffuse light
Data Source
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AI summary
An article inspection system (40) comprises one or more endless article conveyors (11) configured to convey articles (12) along one or more conveying paths (42). One or more light sources and one or more light diffusers (15) are provided, wherein each light diffuser (15) is positioned substantially at or below the level of the articles (12) when conveyed along the conveying paths so as to illuminate, using light from the one or more light sources, at least side portions of the articles (12) with substantially diffuse light when the articles are conveyed along the conveying path(s) (42). At least one camera (46) is positioned to image articles (12) which are conveyed along the conveying paths (42).