Kawamoto Keishin, Tokurei Shogo, Morishita Junji
Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
Department of Radiological Technology, Yamaguchi University Hospital, 1-1-1 Minamikogushi, Ube, Yamaguchi, 755-8505, Japan.
Radiol Phys Technol. 2017 Dec;10(4):409-414. doi: 10.1007/s12194-017-0412-7. Epub 2017 Aug 16.
The luminance uniformity of liquid-crystal displays (LCDs) deteriorates with their prolonged use. In this paper, we present a method for evaluating the degree of luminance non-uniformity of LCDs with the use of a commercially available digital camera. In this study, seven monochrome LCDs, which were used during various operating times ranging from 5000 to 25,000 h, were evaluated with use of a camera. The maximum luminance deviation (MLD) was measured on the two-dimensional (2D) images obtained with the camera. In addition, an index of the luminance non-uniformity was calculated as the ratio of the area exhibiting luminance non-uniformity to the area of the entire LCD screen. We determined the area with the luminance non-uniformity by setting the allowable luminance deviation as the judgment criterion to evaluate the degree of luminance non-uniformity. The MLD values were less than 20% for all conditions, and they varied depending on the locations of the luminance measurement. The area ratios of the luminance non-uniformity based on 2D luminance distributions tended to increase with the duration of use of LCDs, and they indicated the degree of luminance non-uniformity of the LCDs regardless of the measurement locations. Our approach of using a commercially available digital camera showed its potential usefulness for providing more detailed and consistent evaluations of the degree of luminance non-uniformity of LCDs based on the 2D luminance distributions.
液晶显示器（LCD）的亮度均匀性会随着使用时间的延长而变差。在本文中，我们提出了一种利用市售数码相机评估LCD亮度不均匀程度的方法。在本研究中，使用相机对7个在5000至25000小时不等的不同运行时间内使用的单色LCD进行了评估。在相机获取的二维（2D）图像上测量最大亮度偏差（MLD）。此外，将出现亮度不均匀的区域面积与整个LCD屏幕面积的比值作为亮度不均匀性指标进行计算。我们通过将允许亮度偏差设定为判断标准来确定亮度不均匀的区域，以评估亮度不均匀程度。在所有条件下，MLD值均小于20%，并且它们会因亮度测量位置的不同而有所变化。基于2D亮度分布的亮度不均匀区域面积比往往会随着LCD使用时长的增加而增大，并且无论测量位置如何，它们都能表明LCD的亮度不均匀程度。我们使用市售数码相机的方法显示出其潜在的有用性，可基于2D亮度分布对LCD亮度不均匀程度提供更详细和一致的评估。
