Coated Surface Inspection via Multi-Angle Color Detection
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Solution Overview
Problem
Existing methods for inspecting coated glass surfaces, such as those used in facades, are complex and costly due to the need for multiple spectrometers to ensure color homogeneity and detect defects like color deviations, bubbles, and scratches, especially when large areas require uniform color appearance without angle-dependent changes.
Innovation Solution
A device with a light source and multiple cameras positioned to capture reflected light from a coated surface at different viewing angles, allowing for simultaneous inspection of color values from various points, enabling the detection of color deviations and defects by comparing color values across different angles and evaluating them against predefined targets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple spectrometers are used to inspect color homogeneity, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple spectrometers into a single integrated inspection device that captures color information from multiple viewing angles simultaneously. This merging approach maintains the measurement precision of multiple spectrometers while reducing device complexity by consolidating the system into one unit with a single camera and strategic light source positioning.
Solution Approach 2:
The patent introduces a new dimension to color inspection by capturing images at multiple viewing angles (different spatial dimensions) rather than using multiple spectrometers at a single angle. This dimensional approach allows the system to detect color deviations and iridescence effects that traditional single-angle spectrometers miss, improving measurement precision without proportionally increasing device complexity.
2Measurement precision
If multiple spectrometers are used to scan the surface point by point, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The patent uses a light source positioned at a specific angle to pre-illuminate the surface, creating specular reflections that highlight color deviations and iridescence effects before the camera captures the image. This preliminary lighting action enhances the visibility of defects, allowing the single camera to achieve measurement precision comparable to multiple spectrometers while maintaining high inspection speed.
Solution Approach 2:
The patent creates multiple virtual viewing angles by positioning the light source and camera to capture reflections from different apparent angles simultaneously. This copying approach allows the system to obtain color information from multiple perspectives in a single shot, improving detection accuracy without requiring multiple physical spectrometers or sequential scanning, thus maintaining high productivity.
3Device complexity
If a single camera is used to capture reflected light, then device complexity is reduced, but measurement precision decreases
Solution Approach 1:
The patent changes the parameters of the inspection system by positioning the light source at a specific oblique angle (e.g., 45 degrees) relative to the camera axis, rather than using multiple cameras at different angles. This parameter change allows a single camera to capture specular reflections that contain color information from multiple effective viewing angles, maintaining measurement precision while reducing device complexity.
Solution Approach 2:
The patent introduces the light source as an intermediary element that mediates between the surface and the camera. By positioning the light source at a specific angle, it creates specular reflections that carry color information from different viewing angles to the single camera sensor, enabling the simple single-camera system to achieve measurement precision comparable to complex multi-spectrometer systems.
4Measurement precision
If the light source is positioned at an angle to the surface, then color deviation detection is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by positioning the light source at a specific oblique angle (e.g., 45 degrees) relative to the surface normal, rather than using uniform illumination from all directions. This localized angular positioning creates specular reflections that selectively highlight color deviations and iridescence effects at specific locations on the surface, improving detection accuracy without requiring complex multi-directional lighting 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
This solution simplifies and cost-effectively inspects large coated surfaces for color homogeneity and defects, reducing the complexity of existing methods by using a single device to determine color deviations and defects with high accuracy across varying viewing angles.
Implementation Method 1
the first camera is arranged above an inspection line lying on the surface at an angle to the light source, in such a way that it sees the specular reflection of the light emitted by the light source on the coated surface
Implementation Method 2
Coated surfaces, especially those with multiple layers, form interferences (interference layers), which cause the surfaces to show different colors at different viewing angles
Data Source
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AI summary
The present invention relates to a device for inspecting a material (2) provided with a coated surface, preferably glass, which is suitable for simple and cost-effective color inspection.The device comprises a light source (18) arranged above the surface, which emits light in a predetermined wavelength range towards the surface, and at least one first camera (11, 11 11", 14'), wherein the first camera (11, 11 11", 14') is configured to determine a color value of the detected light, wherein the first camera (11, 11 11", 14') is arranged above a line lying on the surface at an angle to the light source and has a first large opening angle (21) such that light from the light source (18) reflected from a first point of the line can be detected separately at a first viewing angle and light from a second point of the line spaced apart from the first point can be detected separately at a second viewing angle, wherein the at least one first camera (11, 11', 11", 14') determines a first color value of the light reflected from the first point and a second color value of the light reflected from the second point.Furthermore, an evaluation device connected to the first camera (11, 11 11", 14') is provided, which compares the first color value and the second color value, or their difference, with a specific, predetermined color target value or with a specific, predetermined color target value range. A method for color inspection is also proposed.