Zhang Tengda, Dong Jingtao, Yang Lei, Liu Shanlin, Lu Rongsheng
Anhui Province Key Laboratory of Measuring Theory and Precision Instrument, School of Instrument Science and Optoelectronics Engineering, Hefei University of Technology, Hefei 230009, Anhui, China.
Rev Sci Instrum. 2021 Oct 1;92(10):103701. doi: 10.1063/5.0060636.
Automatic inspection of micro-defects of thin film transistor-liquid crystal display (TFT-LCD) panels is a critical task in LCD manufacturing. To meet the practical demand of online inspection of a one-dimensional (1D) line image captured by the line scan visual system, we propose a robust 1D Fourier reconstruction method with the capability of automatic determination of the period Δx of the periodic pattern of a spatial domain line image and the neighboring length r of the frequency peaks of the corresponding frequency domain line image. Moreover, to alleviate the difficulty in the discrimination between the defects and the non-uniform illumination background, we present an effective way to correct the non-uniform background using robust locally weighted smoothing combined with polynomial curve fitting. As a proof-of-concept, we built a line scan visual system and tested the captured line images. The results reveal that the proposed method is able to correct the non-uniform illumination background in a proper way that does not cause false alarms in defect inspection but also preserves complete information about the defects in terms of the brightness and darkness as well as the shape, indicating its distinct advantage in defect inspection of TFT-LCD panels.
薄膜晶体管液晶显示器（TFT-LCD）面板微缺陷的自动检测是液晶显示器制造中的一项关键任务。为了满足对线扫描视觉系统捕获的一维（1D）线图像进行在线检测的实际需求，我们提出了一种鲁棒的1D傅里叶重建方法，该方法能够自动确定空间域线图像周期性图案的周期Δx以及相应频域线图像频率峰值的相邻长度r。此外，为了减轻区分缺陷与非均匀照明背景的难度，我们提出了一种有效的方法，即使用鲁棒的局部加权平滑结合多项式曲线拟合来校正非均匀背景。作为概念验证，我们构建了一个线扫描视觉系统并测试了捕获的线图像。结果表明，所提出的方法能够以适当的方式校正非均匀照明背景，既不会在缺陷检测中引起误报，又能在亮度、暗度以及形状方面保留有关缺陷的完整信息，这表明其在TFT-LCD面板缺陷检测中具有明显优势。
