Inspection of Polymer Polaroid’s Visual Defects with Stripe Light Illumination

Abstract

The visual defects of the polymer polaroid have a direct and serious influence on the quality of TFT-LCD panels. A variety of image detection systems have been proposed and widely used by the manufacturers of polaroid and panels in order to detect the visual defects at the earliest possible stage in the production process. Some slight visual defects, however, are barely visible in the images acquired by a camera when under a common illumination condition. In order to deal with this problem, we present a novel machine vision system in which a stripe light source is introduced to illuminate the polaroid sample, and these special defects therefore become more visible. At the base of the aforementioned image enhancement, a straightforward and fast image processing algorithm is designed and implemented. The Morphology Template Method is investigated and the shapes, the locations and the sizes of the visual defects are extracted successfully. The experimental results demonstrate this methodology’s validity to inspect the visual defects of transparent multilayer polymer films.