Adaptive Spectrum Inspection for Lighting Device Assembly Defects
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Solution Overview
Problem
Existing computer vision techniques in LED assembly processes struggle to accurately recognize defects, particularly in distinguishing white object features from white backgrounds or quasi-transparent components, leading to incorrect or missed defect detection.
Innovation Solution
An inspection system that uses a light source with a first light output spectrum to provide luminance contrast, captures images, determines luminance contrast measures, adapts the light spectrum if necessary, and compares images with references to identify defects in LED-based lighting devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If visual light-based imaging technologies are used for inspection, then the inspection system can capture images of the lighting device, but the system fails to provide sufficient luminance contrast between white object features and white background, leading to incorrect or missed defect detection
Solution Approach 1:
The patent changes the spectral parameter of the illumination light from conventional visual light to ultraviolet light with wavelength between 300nm and 400nm. This parameter change enables the base plate to exhibit fluorescence while white object features do not, creating sufficient luminance contrast for accurate defect detection between previously indistinguishable white elements.
2Reliability
If conventional illumination is used to capture images of white components, then the imaging unit can record the components, but the luminance contrast between white components and white background is insufficient, making defect recognition very difficult
Solution Approach 1:
The patent applies ultraviolet illumination with wavelength between 300nm and 400nm to induce fluorescence in the base plate while white components remain non-fluorescent. This creates high luminance contrast that enables reliable defect recognition, distinguishing white components from white background that was previously impossible with conventional visual light.
3Measurement precision
If standard light sources are used for illumination, then the inspection process can proceed with conventional imaging, but the system cannot distinguish fluorescent base plate features from non-fluorescent components, leading to wrong defect detection
Solution Approach 1:
The patent specifies using ultraviolet light with wavelength between 300nm and 400nm to illuminate the lighting device. This spectral parameter enables the base plate material to fluoresce while white-painted components and quasi-transparent lens plates do not fluoresce, creating distinct luminance differences that allow accurate feature distinction and prevent wrong defect detection.
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
Improves defect recognition in LED-based lighting devices by optimizing light output spectrum for enhanced luminance contrast, enabling accurate detection of alignment, misplacement, and other defects during assembly.
Implementation Method 1
a light source arranged for illuminating the lighting device according to a first light output spectrum for providing a luminance contrast between the base plate and the plurality of components
Implementation Method 2
an imaging unit arranged for capturing a first image of the illuminated lighting device
Data Source
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AI summary
An inspection system (100) for inspecting a lighting device (150) during an assembly process of the lighting device; wherein the lighting device comprises a base plate (153) and a plurality of components (155) mounted on the base plate; wherein the inspection system comprises: a light source (120) arranged for illuminating the lighting device according to a first light output spectrum for providing a luminance contrast between the base plate and the plurality of components; an imaging unit/camera (130) arranged for capturing a first image of the illuminated lighting device; a controller (110) comprising a processing unit for determining a luminance contrast measure of the captured first image; wherein the processing unit is further arranged for, when the luminance contrast measure of the captured first image exceeds a threshold value, adapting the first light output spectrum, and wherein the imaging unit is further arranged for capturing a second image of the lighting device illuminated according to the adapted first light output spectrum; and wherein the controller further comprises: a comparing unit arranged for comparing the second image with a reference image; a determination unit arranged for determining a defect in the base plate and/or in the plurality of components based on the comparison.