Surface Inspection Apparatus with Multi-Group Fiber Sensitivity
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Solution Overview
Problem
Conventional surface inspection apparatuses have fixed sensitivity characteristics, making them inadequate for detecting changes in defect types and locations, and are prone to errors due to misalignment between the inspection head and cylindrical body, leading to periodic density variations in two-dimensional images and reduced sensitivity due to protective window reflections.
Innovation Solution
A surface inspection apparatus with multiple light receiving fiber groups and adjustable sensitivity characteristics, using photoelectric converting means and arithmetic rules to combine signals and control inspection light intensity, allowing for varied sensitivity settings and alignment-independent imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single light receiving fiber group is used, then the device structure is simple, but the sensitivity characteristics are fixed and cannot detect different defect types
Solution Approach 1:
The light receiving fibers are divided into multiple groups (first light receiving fiber group and second light receiving fiber group) with different positional relationships to the light projecting fiber. Each group provides different sensitivity characteristics, allowing the system to detect various defect types by selecting or combining signals from different groups.
Solution Approach 2:
The inspection apparatus is designed to perform multiple inspection functions using a single device structure. By incorporating multiple light receiving fiber groups with different configurations, the apparatus can detect different defect types (surface defects, subsurface defects, foreign matter) without requiring separate inspection devices.
2Measurement precision
If the inspection head is misaligned with the cylindrical body, then the imaging process is simplified, but periodic density variations occur in the two-dimensional image
Solution Approach 1:
The system extracts frequency components from the reflected light signal that correspond to misalignment between the inspection head and cylindrical body. Based on this feedback, the light source intensity is dynamically adjusted to compensate for misalignment effects, eliminating periodic density variations in the generated two-dimensional image.
Solution Approach 2:
The light source intensity is dynamically adjusted based on the extracted frequency components indicating misalignment. By changing the light intensity parameter in response to detected misalignment, the system compensates for positioning errors and maintains high image quality without requiring precise mechanical alignment.
3Reliability
If a protective window member is added, then the head tube is protected from contamination, but sensitivity is reduced due to light reflections
Solution Approach 1:
The harmful reflected light from the protective window member is extracted and separated from the useful reflected light signal. By identifying and removing the unwanted reflection components, the system maintains detection sensitivity while the protective window continues to protect the head tube from contamination.
Solution Approach 2:
The system uses signal processing as an intermediary to distinguish between useful reflected light (from inspection defects) and harmful reflected light (from the protective window). Through frequency analysis and selective filtering, the intermediary processing separates these light components, allowing the protective window to remain in place without degrading detection sensitivity.
4Adaptability or versatility
If multiple light receiving fiber groups are used, then different defect types can be detected, but the signal processing becomes complex
Solution Approach 1:
The signal processing system dynamically selects and combines signals from different light receiving fiber groups based on the type of defect being inspected. Rather than processing all signals simultaneously with fixed complexity, the system adapts its processing approach to match the inspection requirements, reducing unnecessary computational complexity while maintaining comprehensive defect detection capability.
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
Enables accurate detection of defects without periodic density variations and improved sensitivity by adjusting sensitivity characteristics and controlling light intensity, enhancing inspection precision and accuracy.
Implementation Method 1
a light source that projects inspection light onto a surface of an inspection object through a light projecting fiber
Implementation Method 2
a first photoelectric converting means that outputs a signal according to the intensity of the reflected light guided by the first light receiving fiber group; and a second photoelectric converting means that outputs a signal according to the intensity of the reflected light guided by the second light receiving fiber group
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A surface inspection apparatus 1 has a detection unit 5 that irradiates an inner circumferential surface 100a of an inspection object 100 with inspection light from a laser diode 11 through a light projecting fiber 13, and detects the intensity of the reflected light of that inspection light. The detection unit comprises a first light receiving fiber group 14A, which is disposed at the circumference of the light projecting fiber 13, a second light receiving fiber group 14B, which is disposed further on the outer side thereof, and photodetectors 12A and 12B, which are connected to each of the fiber groups.