Appearance Inspection Apparatus Using Multi-Wavelength Slit Light
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Solution Overview
Problem
Conventional tire appearance inspection methods fail to accurately distinguish between surface unevenness and other conditions like 'shine' or 'change in color tone' due to the limited use of red and blue light, leading to detection errors.
Innovation Solution
An appearance inspection apparatus utilizing a slit light with an intermediate wavelength, along with red and blue lights, to detect surface unevenness and color tone changes by synthesizing reflected luminance and surface data, enabling precise detection of gloss and extraneous color defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If only red and blue lights are used for surface inspection, then the inspection system is simple, but the detection accuracy deteriorates because shine and color tone changes cannot be properly distinguished from surface unevenness
Solution Approach 1:
The inspection system is segmented into three independent illumination channels (red, green, blue lights) that can be controlled separately. Each wavelength illuminates the surface from different directions, and the imaging device captures images for each wavelength independently. This segmentation allows the system to analyze reflectance characteristics at different wavelengths separately, enabling accurate distinction between shine, color tone changes, and surface unevenness without mixing the detection signals.
Solution Approach 2:
The system changes the illumination parameter by using three different wavelengths (red, green, blue lights) instead of a single or dual wavelength. This parameter change enables the detection of wavelength-dependent reflectance characteristics, where shine shows strong wavelength dependence, color tone changes show specific wavelength patterns, and surface unevenness shows different patterns. By analyzing the reflectance at multiple wavelengths, the system achieves accurate defect classification.
2Productivity
If red and blue lights are overlapped to detect surface unevenness, then the inspection process is efficient, but detection errors occur when shine or color tone changes are misidentified as surface unevenness
Solution Approach 1:
The imaging process is segmented into three separate wavelength-specific imaging operations. The imaging device captures images illuminated by red light, green light, and blue light separately, rather than relying on overlapped red and blue illumination. This segmentation produces three distinct image sets that can be analyzed independently to determine reflectance characteristics at each wavelength, preventing misidentification of defects while maintaining inspection efficiency through automated multi-wavelength analysis.
Solution Approach 2:
The system introduces green light as an intermediary wavelength between red and blue illumination. This intermediary wavelength provides additional information about the surface reflectance characteristics. By comparing the reflectance patterns across red, green, and blue wavelengths, the system can reliably distinguish between different defect types (shine, color tone changes, surface unevenness) without the detection errors that occur with dual-wavelength systems.
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
The apparatus effectively differentiates between surface unevenness, shine, and color tone changes, enhancing the accuracy of tire shape and surface condition inspections by using a combination of green, red, and blue light to capture detailed surface information.
Implementation Method 1
a first illuminating means for casting a slit light having an intermediate wavelength, of three types of lights having different wavelengths from each other, on a surface of a sample under inspection, a first imaging means for acquiring reflected luminance data on the surface of the sample by receiving reflected light of the slit light
Data Source
AI summary
An appearance inspection apparatus and an appearance inspection method for detecting a shape, surface unevenness, shine or changes in tone on the surface. The method includes steps of acquiring reflected luminance data on the sample surface by casting a slit light having an intermediate wavelength of three types of lights having different wavelengths, receiving reflected light of the slit light, acquiring surface data by casting two lights of different wavelengths other than the intermediate wavelength at a position other than the position illuminated by the slit light on the sample surface from two different directions so as to overlap two lights with each other and receiving reflected light, detecting surface unevenness from a ratio between the intensities of lights, changes in tone by combining reflected luminance data and surface data, gloss on the sample surface based on the presence or absence of surface unevenness and the changes in color tone.