Design of Automated Optical Inspection System of Touch Panels
| Autor: | Li, Jen-Miao, 李仁淼 |
|---|---|
| Rok vydání: | 2014 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 102 Capacitive touch panels (CTP) with advantages of water-proof, stain-proof, scratch-proof, fast response, are widely used in various electronic products. The surface of CTPs are multi-layer structured and are classified as structural textures. It is a difficult inspection task when defects embedded in surface of CTPs with structural textures. The surface defects are usually classified into linear and area types of defects. The area type includes dirt, water marks, bubbles and other defects with larger scope. Such defects have low contrast, brightness with gradient changes, irregular and non-directional shapes. The linear type defect is commonly caused by scratch and has directionality. Both of the defect types may appear simultaneously on product surfaces in the CTP production line. In this study, we propose a novel approach to detect the two types of defects on CTP surfaces. The proposed method applies the Curvelet Transform (CT) with multi-angle filtering to remove the structural textures of background and delete the angle direction of background texture. Then the filtered image is inversely transformed back to spatial domain. In the reconstructed image, the background texture is attenuated and the defects are enhanced. Finally, a thresholding value is determined by statistical control limits and the restored image can be easily segmented to into two categories namely dark defects, and white background. Experimental results show that the proposed method achieves a high 92.26% flaw detection rate (1-β), a low 1.32% false alarm rate(α), a high 98.61% correct classification rate (CR). |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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