PCB Appearance Inspection Using Reconstructed Image Comparison
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Solution Overview
Problem
Existing board appearance inspection apparatuses require mechanisms to reverse the board for imaging, making integration into existing conveyance lines difficult and necessitating a more complex configuration.
Innovation Solution
An appearance inspection apparatus utilizing an imaging unit, reconstructed image generation, and image comparison to inspect for anomalies without reversing the board, employing a model to reconstruct and compare input images for anomaly detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the imaging device is disposed to face the solder surface for capturing downward view images, then the inspection accuracy for component attachment state is improved, but the device complexity increases due to requiring a board reversal mechanism
Solution Approach 1:
Instead of positioning the imaging device to face the solder surface directly (which would require board reversal), the patent inverts the approach by using image processing techniques to analyze the component surface images. The normal vector calculation and projection methods allow inspection of solder joint issues by analyzing component surface geometry, eliminating the need for physical board reversal while maintaining inspection capability
Solution Approach 2:
The patent replaces the mechanical board reversal mechanism with computational image processing methods. By calculating normal vectors from component surface images and projecting them onto the board surface, the system achieves solder surface inspection functionality through software algorithms rather than mechanical board manipulation, thereby reducing device complexity
2Reliability
If the board is reversed to capture the solder surface, then the inspection capability for component attachment is improved, but the ease of operation deteriorates due to difficulty in integrating with existing conveyance lines
Solution Approach 1:
The patent inverts the traditional inspection approach by not reversing the board but instead using computational geometry methods on component surface images. The normal vector calculation and projection techniques allow the system to derive solder joint information from component surface views, enabling integration with existing conveyance lines that move boards in the original orientation without requiring reversal mechanisms
3Measurement precision
If a conventional imaging setup is used to inspect the solder surface, then the measurement precision is improved, but the device complexity increases due to additional mechanisms required
Solution Approach 1:
The patent substitutes mechanical imaging setups that require direct solder surface viewing with a computational approach. By extracting normal vectors from component surface images and projecting them onto the board surface, the system achieves precise measurement of component attachment state and solder joint quality through mathematical processing rather than direct optical imaging of the solder surface, thereby reducing device complexity
Data Source
AI summary
An appearance inspection apparatus includes an imaging unit, a reconstructed image generation unit, and an image comparison unit. The imaging unit images an object. The reconstructed image generation unit generates a reconstructed image by using a model, the reconstructed image being an image to be obtained by reconstruction of an input image, image data on the object imaged by the imaging unit being used as the input image, the model being used for attempting to reproduce the image data. The image comparison unit generates a difference image corresponding to a difference between the input image and the reconstructed image.