Foreign Substance Inspection Device Using Pixel-Source Mapping
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Solution Overview
Problem
Conventional inspection systems struggle to detect foreign substances, defects, and scratches in thick inspection objects with light scattering properties, due to limited depth of field and interference from scattered light.
Innovation Solution
The system employs a light source with a large depth of field and a light receiving optical system where each light receiving element corresponds to a specific light source, allowing only scattered light from foreign substances or defects to be detected while minimizing crosstalk between pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional inspection system with limited depth of field is used, then the device complexity is reduced, but the ability to detect foreign substances in thick inspection objects deteriorates
Solution Approach 1:
The light receiving elements are arranged in a matrix pattern with multiple rows and columns, allowing the system to segment the detection space into multiple depth zones. Each light receiving element corresponds to a specific light source, enabling independent detection at different depths within the thick inspection object while maintaining manageable device complexity through modular arrangement
Solution Approach 2:
The patent transitions from conventional two-dimensional surface inspection to three-dimensional volumetric inspection by arranging light sources and light receiving elements in corresponding spatial positions. This dimensional extension allows detection of foreign substances at various depths within thick objects, not just on the surface
2Measurement precision
If a light source with large depth of field is used to inspect thick objects, then the detection ability improves, but the background noise from scattered light increases
Solution Approach 1:
Each light receiving element is positioned to correspond with a specific light source, creating localized detection zones. This local quality arrangement ensures that each detector receives light primarily from its paired source, minimizing interference from scattered light of other sources and reducing background noise while maintaining detection capability throughout the thick object
Solution Approach 2:
The patent uses optical elements such as lenses or mirrors as intermediaries to guide and focus light from specific light sources to corresponding light receiving elements. These intermediaries help maintain clear optical paths and reduce the mixing of scattered light from different sources, thereby reducing background noise
3Area of stationary object
If multiple light sources are used to cover the entire inspection object, then the detection coverage improves, but the crosstalk between pixels increases
Solution Approach 1:
The light receiving elements are arranged in a matrix with multiple rows and columns, segmenting the detection area into multiple independent detection zones. Each light receiving element corresponds to a specific light source, creating spatially separated detection channels that minimize crosstalk while collectively covering the entire inspection object
Solution Approach 2:
The patent uses more light sources and light receiving elements than the minimum required for simple coverage. This excessive arrangement ensures that each detector has a dedicated light source, providing redundancy and minimizing crosstalk by ensuring that even with multiple active sources, each detector primarily responds to its paired source
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 accurate detection of foreign substances and defects in thick light scattering media, even when the media has high transmittance, by reducing background noise and improving signal-to-noise ratio.
Implementation Method 1
a light source with a large depth of field and a light receiving optical system where each light receiving element corresponds to a specific light source, allowing only scattered light from foreign substances or defects to be detected
Data Source
AI summary
According to the present invention, a light source and one pixel unit formed of at least one light reception element among a light reception element array (photodiode array) are provided in a one-to-one correspondence, and a light beam is detected from at least one light reception element (one pixel unit) corresponding to the light source, only when the light source emits light. Therefore, only one collimated or further substantially condensed light beam is incident into “a foreign substance/defect” in an object to be inspected, and only scattered light can be separated by the light reception element and be detected. Accordingly, even when an object to be inspected has a light scattering property and is thick, “a foreign substance/defect” can be detected with a good signal to noise ratio (crosstalk is extremely low).