Appearance Inspection Device Stray Light Exclusion
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Solution Overview
Problem
Appearance inspection devices face challenges in accurately detecting defects, particularly solder protruding defects on circuit boards, due to stray light reflections from solder fillets, which can lead to erroneous height measurements.
Innovation Solution
An appearance inspection device with an imaging unit, a height measurement unit, a moving mechanism, a determination unit, and a restriction unit that restricts the use of height information from areas prone to stray light reflections, allowing for accurate defect determination by excluding specific regions from the inspection area where stray light is likely to occur.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If height measurement is performed using reflected light from the solder fillet slope, then height measurement capability is improved, but measurement precision deteriorates due to stray light reception
Solution Approach 1:
The inspection region is divided into a measurement region (where height measurement is performed) and a non-measurement region (where stray light may be generated). By segmenting the region and applying different processing rules, the patent resolves the contradiction between maintaining height measurement capability and preventing erroneous defect detection from stray light.
Solution Approach 2:
Different quality standards are applied to different regions: in the measurement region, height information is used for defect detection, while in the non-measurement region, height information is excluded or given lower weight to prevent stray light interference. This local differentiation resolves the contradiction between measurement accuracy and detection reliability.
2Area of stationary object
If the imaging unit and height measurement unit inspect the entire inspection region, then inspection coverage is improved, but detection accuracy deteriorates due to stray light from solder fillets
Solution Approach 1:
The inspection region is segmented into measurement regions and non-measurement regions based on the likelihood of stray light generation. This segmentation allows comprehensive inspection coverage while excluding problematic areas from height-based defect detection, resolving the contradiction between coverage and accuracy.
Solution Approach 2:
The patent performs height measurement on the entire inspection region (excessive action) but only uses the results from specific measurement regions for defect detection (partial action). This approach maintains comprehensive data collection while ensuring accurate defect detection by excluding stray light-affected areas.
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 configuration enhances the accuracy of defect detection by preventing erroneous readings caused by stray light, specifically in the case of solder protruding defects on circuit boards, by excluding regions where measurement light is reflected multiple times and received as stray light.
Implementation Method 1
a height measurement unit configured to emit measurement light and receive reflected light of the measurement light to measure a height of a predetermined place in the inspection target
Implementation Method 2
when the slope of the solder fillet 30b is irradiated with the measurement light, reflected light of the measurement light may be further reflected by another part of the circuit board and received by the height measurement device as stray light
Data Source
AI summary
Provided is a technique capable of more accurately determining a solder protruding defect in an appearance inspection device that acquires an image of an inspection region of an inspection target and measures a height of a predetermined place in the inspection region with a height measurement device. The appearance inspection device includes: an imaging unit (3); a height measurement unit (20); a moving mechanism (5) that moves the imaging unit (3) and the height measurement unit (20). When a restricted region (M) in the inspection target is irradiated with the measurement light emitted from the height measurement unit (20), the determination unit restricts defect determination based on the information on the height of the predetermined place measured by the height measurement unit (20).