Quality Inspection of Characters Printed on Chip Resistors

Abstract

An automatic defect inspection algorithm for characters printed on chip resistors is described in this paper. Three characters representing electric resistance are usually printed on chip resistors. Though automatic defect inspection systems for printed circuits have already been developed, the quality of the characters printed on chip resistors is still examined by visual inspection. An automatic quality inspection system for the characters printed on such small chip resistors is required. This paper describes quality inspection algorithm based on the fuzzy theory obtained from ambiguous criteria for judgement which have been adopted in visual inspection. With an experiment using 70 chip resistors, 90.3% accuracy in the identification is obtained.