Highresolution Defect Inspection for Transparent Indiumtinoxide Conductive Film

为识别铟锡氧化物导电薄膜透明区域内可能存在的加工型和移交型缺陷，并满足实际应用需求，提出了基于高分辨率视觉系统的自动缺陷识别方法.根据铟锡氧化物薄膜光学特性和空间要求，设计了工作距离为30 mm的科勒式同轴光照明模块.此外，为了与照明部分通用光学元件，设计了适用于应用检测的高分辨率成像模块.完成图像采集后，为便于分别检测两类缺陷，采用了两种预处理方法：对图像进行邻域半径r=7的中值滤波并与原图像相减后，获取清晰的划痕缺陷；对图像进行形态学和与阈值处理后，获取对比度为48%的透明电路图案.处理后的图像为缺陷的自动识别提供了可靠的依据，保障了铟锡氧化物薄膜定位的灵敏度和准确度. The transparent area of indium tin oxide conductive film possibly has two kinds of defects, processing-type and handling-type. According to the characteristics of different defects and requirements from practicable application, an automatic method for defect inspection based on high-resolution vision system was proposed. In the system, a coaxial lighting module using Koler configuration was designed, which was suitable for optical property of indium tin oxide film and meets space requirement of working distance 30 mm. In addition, the high-resolution imaging module applied to practicable inspection was also designed. It shared a doublet lens with lighting module. After obtaining image of indium tin oxide film, two image pre-processing methods were exploited to inspect each kind of defect respectively. If subtracted image processed by median filter in neighboring radius r=7 from original image, scratch defect could be kept clearly. If processed original image by morphological and threshold method successively, transparent circuit pattern could be observed remarkably. The contrast of the pattern image was increased to 48%. The images after being pre-processed provide reliability for automatic defect recognition, and guarantee sensitivity and accuracy to location of indium tin oxide film. © 2016, Science Press. All right reserved.