高分子有機發光二極體瑕疵自動光學檢測系統

Abstract

高分子有機發光二極體顯示面板(Polymer Light Emitting Display, PLED) 基本結構是由一薄而透明具半導體特性之銦錫氧化物與電力之正極相連，再加上另一個金屬陰極，包成如三明治的結構。因其具有自發光(不需要背光)、視角廣、亮度高、需求電壓低、省電效率高、反應快、重量輕、厚度薄、構造簡單和成本低等優點，被視為 21世紀最具前途的產品之一。但是製造廠商因製程因素，在PLED成品上容易發生諸多瑕疵如：暗點、蓋板刮傷（surface scratch）、亮度不均勻、色純度不一致和膠寬（rubber width）過窄等。製造廠現階段是利用人工目視來檢測這些瑕疵，但人工目視檢測容易發生疲勞、正確性不佳等問題。本研究開發檢測演算法來對這些瑕疵進行自動檢測，以改善PLED平面顯示元件成品檢測的成效。上述瑕疵可依據發光點和外觀兩個指標將之分為兩類進行檢驗。第一類瑕疵檢驗包括暗點和亮度不均之檢驗，採用自行設計的夾具並通以3V電壓使PLED發光進行取像，再利用檢測演算法進行瑕疵偵測。而暗點瑕疵的發生，可歸因於PLED結構缺陷所造成，本研究採用背光和UV光源針對暗點瑕疵進行取像及檢測，以偵測該瑕疵是屬PLED哪一層三明治結構所引起。第二類瑕疵檢驗為PLED外觀問題，包括蓋板刮傷和膠寬過窄之檢驗，本研究採用LED同軸光源進行取像及檢測。本研究所發展之自動光學檢測系統對於PLED成品瑕疵檢測可達到快速、穩定、準確的效果，並可提供所檢測出之瑕疵是屬PLED哪層結構所造成的資訊，以幫助製造商改善其製程。

Polymer light emitting diode (PLED) stacks up several thin layers of materials, including PF layer, metal layer and ITO layer. Without any other source of luminance, PLED materials present bright, clear video and images that are easy to see at almost any angle. Thus, the inspection of commonly observed PLED defects such as dark point, surface scratch, non-uniform luminance, lack of color uniformity, and insufficient rubber width, etc, are an important issue of PLED industry. An AOI system, which can inspect all the listed defects, was developed to improve the inspection speed and quality. Luminance and outward appearance are important quality indicators of PLED panel. The defects listed above can be classified into two classes by these two indicators. Class I defect is related with PLED luminance, including dark point and non-uniform luminance. A conducting fixture was designed to have the PLED panel be conducted and lit up with 3 Voltage. In order to detect which layer was broken, we use (a) an UV light to stimulate the PF layer, and (b) a back light to illuminate the metal layer for image grabbing. Class II defect is related with outward appearance, including surface scratch and insufficient rubber width. The coaxial LED light is used for image grabbing. The proposed AOI system can detect the above mentioned defects effectively and robustly. Such AOI system can provide great help for improving the PLED quality control process and production process.