为解决线阵CCD 用于投射电容屏氧化铟锡(ITO)电路检测时不易获取高对比度图像的问题，根据明场照明反射成像原理，设计并构建了一套基于最大叠加反射系数差值的同轴照明与成像系统．根据投射电容屏ITO 电路与玻璃基板的光学特性及ITO 电路的几何特征，分析了光源照射及成像方式;根据ITO 电路的多层复合结构， 分析了影响 ITO 电路与玻璃基板成像对比度的影响因素;在满足较高生产率的运动速度下，通过对比不同光照亮度下所获取的系列图像，确定了可获得高对比度 ITO 电路与玻璃基板图像的成像系统工作参数．实验结果表明:检测精度为10 μm、ITO 基板运动速度为130 mm/s 且光照亮度等级为190 时，所获图像的灰度直方图具有显著双峰值，易于识别ITO 电路缺陷．

In order to acquire high- contrast images in the defect inspection of the PCTP (Projected Capacitive Tou- ch Panel) ITO pattern by using the line- scan CCD,a coaxial illumination and imaging system based on the maxi- mum difference value between superposed reflection coefficients is designed and established according to the bright- field reflection illumination principle.Then,the illumination and imaging patterns are analyzed by taking into ac- count the optical properties of the glass substrate,the PCTP ITO material as well as the geometrical structure of the ITO pattern,and the influence factors of the imaging contrast between the ITO film and the glass substrate are ana- lyzed by considering the multi- layered composite structure of the ITO pattern.Finally,at a higher scan rate which can cause a higher productivity,the imaging parameters of the high- contrast images of the ITO pattern and the glass substrate are determined by comparing a series of images taken at different illumination intensities.Experiment re- sults indicate that,when the ITO substrate scans at a rate of 130mm/s with an inspection precision of 10μm and a light intensity of 190,image gray histograms have two apparent peaks,which helps to inspect the defects of ITO patterns.