Inspection Device Signal Saturation Prevention
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Solution Overview
Problem
Existing inspection devices face challenges in accurately detecting defects when the intensity of scattered light from an inspection object varies significantly across its surface, leading to potential saturation of detection signals and difficulties in distinguishing between normal and defective portions.
Innovation Solution
The inspection device utilizes a history of detection signals to predict whether the next signal level will exceed a threshold, adjusting its operations to prevent saturation by reducing the intensity of illumination or detection sensitivity, or modifying the inspection algorithm to maintain signal levels within manageable limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single inspection threshold is used for all portions of the inspection object, then the device complexity is reduced, but the measurement precision deteriorates when scattered light intensity varies greatly across different portions
Solution Approach 1:
The inspection object surface is divided into multiple regions with different inspection thresholds. The threshold setting unit establishes separate thresholds for each region based on the scattered light intensity characteristics of that region, allowing precise defect detection adapted to local surface variations without requiring complex global threshold adjustment mechanisms
Solution Approach 2:
Inspection thresholds for all regions are predetermined and stored in advance before the actual inspection process. The threshold setting unit prepares region-specific thresholds based on pre-acquired scattered light intensity data, enabling the inspection device to quickly apply appropriate thresholds without real-time calculation delays during defect detection
2Measurement precision
If the inspection threshold is increased to detect defects in high-scattered-light portions, then the detection sensitivity for those portions improves, but the ability to detect defects in low-scattered-light portions deteriorates
Solution Approach 1:
Each region of the inspection object is assigned a customized inspection threshold tailored to its specific scattered light intensity characteristics. High-scattered-light regions receive higher thresholds while low-scattered-light regions receive lower thresholds, ensuring optimal defect detection sensitivity for each local area without compromising other regions
Solution Approach 2:
The inspection threshold parameter is dynamically adjusted according to the scattered light intensity of each region. By changing the threshold parameter locally rather than using a fixed global value, the system adapts to varying surface states and maintains high detection sensitivity across diverse inspection conditions
3Measurement precision
If the detection signal intensity is increased to improve defect detection sensitivity, then the measurement precision improves, but the reliability deteriorates when the signal exceeds the maximum detectable intensity causing saturation
Solution Approach 1:
The system preemptively identifies regions where scattered light intensity may exceed detector limits and applies appropriate threshold adjustments before saturation occurs. By predicting potential signal overflow based on pre-acquired intensity data, the system prevents reliability issues while maintaining detection sensitivity
Solution Approach 2:
The inspection system uses feedback from the scattered light intensity measurements to dynamically adjust inspection parameters. When high intensity signals are detected or predicted, the system adjusts thresholds and detection settings to prevent saturation, ensuring reliable measurements across varying signal conditions
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 sensitive detection of defects even with varying surface states, preventing signal saturation and improving the accuracy of defect identification across different portions of the inspection object.
Implementation Method 1
applies illumination light to an inspection object and detects scattered light reflected from the inspection object
Implementation Method 2
detects scattered light reflected from the inspection object, and thus inspects a surface state of the inspection object
Data Source
AI summary
The invention aims to provide an inspection device that can sensitively detect a defect even if intensity of scattered light reflected from an inspection object greatly varies depending on portions of the inspection object. An inspection device according to the invention uses a history of detection signals to predict whether a next detection signal level exceeds a threshold. When the detection signal level is predicted to exceed the threshold, operation of the device is beforehand changed such that the detection signal level does not exceed the threshold.