Paper
1 December 1991 Moire image overlapping method for PCB inspection designator
Rang-Seng Chang, Yeu-Jent Hu
Author Affiliations +
Abstract
Computer pattern recognition has been expanding its application in various fields. Its application in printed circuit board (PCB) inspection, for example, will accordingly reduce the requirement of manpower as well as the error rate, if equipped with adequate accessories; real time processing can then be implemented with defect locating feature. The design philosophy of this system is focused on how to establish a complete PCB inspection methodology with an error indication for a more effective amending process. The algorithm of this system is as follows: first, use the CCD camera to scan the PCB under inspection, then compare it with the correct one, which has already been stored in the computer memory, and compare the results. If any error exists, then a `+' will be marked on the defect spot from the computer, and overlapping will be executed via a computer-controlled zooming LCD (liquid crystal display) overhead projector. The `+' mark can specify the defect spot clearly. The size and the position of the overlapping image with the tested PCB will be exactly one to one. The optical distortion error is corrected by computer program using the moire and optical analysis method.
© (1991) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Rang-Seng Chang and Yeu-Jent Hu "Moire image overlapping method for PCB inspection designator", Proc. SPIE 1567, Applications of Digital Image Processing XIV, (1 December 1991); https://doi.org/10.1117/12.50816
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KEYWORDS
Inspection

Digital image processing

Moire patterns

LCDs

Projection systems

Error analysis

Image processing

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