Led Cosmetic Flaw Vision Inspection System
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Date
1997-01
Authors
Chu, Jenn Weng
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Abstract
Currently, in the Light Emitting Diode (LED) component industry, one of the
challenges faced by most of the manufacturers is how to effectively eliminate cosmetic
rejects from the finish products. Since there has yet a solution to totally eliminate the
cosmetic rejects from the product by improving their manufacturing processes, various
visual inspection check points need to be established to prevent the reject units from
reaching their customers. This cosmetic flaw inspection process is currently performed
visually by human, however, it is not effective. Hence it was resolved that if the process
can be fully automated, it can reduce manufacturing cost drastically, increase
productivity and improve out-going product quality. Finally the 6 sigma goal and world
class manufacturing can be achieved.
A research and development work in automated vision inspection system to
resolve the above problem is presented in this thesis. The developed system is capable
to detect diffuse LED's defects mimely scratches, bubbles, contamination, fuzzy dome
and off centre in less than 200ms using a 200MHz Pentium PC and a Pulnix high speed
camera. Various image processing techniques are utilised to accomplished the
inspection task. A machine vision approach which comprises pre-processing, image
segmentation, clean up and feature extraction operations, was implemented to perform
the automated cosmetic flaw inspection.
In the laboratory tests conducted, the system was found to be 100% accurate in
detecting LED dome defects on LEDs of different colour and intensity. The system can
also classify defects into different categories and was found to be 90% accurate.
Description
Keywords
Eliminate cosmetic rejects , from the finish products