Light Tester Pinhole Detection Threshold Logic
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Solution Overview
Problem
Conventional pinhole inspection methods using light testers often lead to erroneous rejection of flawless cans due to excessive incident light, especially at higher conveying speeds, causing flawless cans to be incorrectly identified as defective.
Innovation Solution
The light tester employs multiple inspection patterns with varying thresholds, including a constant value, a value adjusted by a judgment value when detection starts increasing, and a value based on the average detection values at entry and exit, to accurately determine the presence of a pinhole, thereby preventing erroneous rejections and reducing re-testing frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the light tester uses a single threshold value for pinhole detection, then the detection process is simple, but flawless cans are erroneously rejected due to excessive incident light from vacant can holders
Solution Approach 1:
The patent divides the detection process into three distinct inspection patterns, each with its own threshold determination method. The first pattern uses a constant threshold, the second uses a threshold based on detection value changes, and the third uses a threshold based on average detection values. This segmentation allows each pattern to handle different detection scenarios, improving overall reliability while maintaining manageable complexity through modular design.
Solution Approach 2:
The patent implements dynamic threshold adjustment by switching between different inspection patterns based on detection conditions. The threshold is not fixed but adapts according to the inspection pattern being used and the detected light transmission values. This dynamic approach allows the system to respond to varying incident light conditions, preventing erroneous rejections while maintaining detection accuracy.
2Productivity
If the light tester operates at high conveying speeds, then productivity increases, but detection accuracy decreases due to delayed response to light reduction
Solution Approach 1:
The patent performs preliminary detection actions by monitoring light transmission values continuously and comparing them against dynamically determined thresholds. The system prepares detection results by evaluating multiple inspection patterns and determining pinhole presence before the can proceeds to the rejection point. This preliminary action ensures accurate detection even at high conveying speeds by making decisions based on accumulated detection data rather than delayed responses.
Solution Approach 2:
The patent implements feedback mechanisms by continuously monitoring detection values and using them to determine threshold values for subsequent comparisons. The system feeds back detection information to adjust the inspection process, allowing real-time adaptation to changing conditions. This feedback loop ensures that detection accuracy is maintained at high conveying speeds by continuously adjusting to the actual light transmission patterns observed.
3Loss of information
If the light sensor detects excessive incident light from vacant can holders, then the detection signal increases, but flawless cans are incorrectly identified as defective
Solution Approach 1:
The patent changes the parameter used for defective can identification from absolute detection signal strength to a relative comparison against dynamically determined thresholds. Instead of rejecting cans based on fixed signal levels, the system compares detection values against thresholds that adapt to the actual lighting conditions and can holder status. This parameter change allows the system to distinguish between genuine pinhole signals and excessive incident light from vacant holders, improving identification accuracy.
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 effectively reduces the rejection of flawless cans and minimizes re-testing by accurately identifying defective cans through simultaneous use of multiple inspection patterns, even when the light sensor is affected by excessive light.
Implementation Method 1
a light source for emitting light to a can body conveyed to an inspection zone, and a light sensor for detecting light transmitting through the can body
Data Source
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AI summary
A light tester that can prevent a rejection of a flawless can due to an erroneous detection of a pinhole is provided. The light tester comprises: a first inspection pattern in which a first value as a constant value is employed as the threshold (Step S3); a second inspection pattern in which a second value is employed as the threshold that is obtained by adding a predetermined judgment value to the detection value detected at a point when the detection value starts increasing in the inspection zone (Step S4); and a third inspection pattern in which a third value is employed as the threshold that is obtained by adding another judgment value to an average value between the detection value detected at a point when the can body enters into the inspection zone and the detection value detected at a point when the can body exits from the inspection zone (Step S5).