图像处理技术在低逸出功印刷型FED中的应用

The Application of Image Processing Technology in Low-work-function Printable Field Emission Display

采用低成本、大面积、低逸出功FED阴极材料及其阴极浆料,研制了大面积印刷式FED(样机),具有自主知识产权,在国内外属首创。介绍了低逸出功可印刷型场致发射显示系统的工作原理、数字视频图像的转换和处理、视频数据的传输、列灰度驱动和行驱动集成电路以及FPGA控制技术等。为了改善场致发射显示器的显示效果,通过理论分析和实际验证提出了亮度非均匀性校正、γ校正、自动功率控制等相应的解决方案。将图像处理技术应用到驱动电路中,改善了图像的亮度均匀性和灰度再现质量,降低了整机的功耗。首次将本技术应用于大屏幕低逸出功印刷型63.5cm(25英寸)VGA级彩色FED驱动系统中,研制出了能显示彩色视频图像的彩色FED显示器样机。亮度达400cd/m2、对比度为1000∶1,电路灰度等级为256级。

Field emission display is a relative novel flat plate display. It is a promising technology as well as liquid crystal display, plasma display panel, OELD. The large-screen printing FED developed with independent intellectual property rights used particular low-cost, large-scale, low work function material and cathode slurry. Different from FED of other types, large-scale printing FED is with low cost, simple technic, and using the materials with low work function, thus it can reduce the emitting voltage, simplify the driving circuit. At present, we have developed 25 inches large-screen printing color field emission display, topping in China. In the year before last, we successfully developed a kind of driving system that realized displaying video on FED panel. The system used special image processing technology. So far, the driving system has been applied to the 640 × 480 FED panel and reached good result. The principle of low work function printable field emission display system was presented including the transform and processing of digital video image, the transmission of video data, the interface circuit, the grayshade of column driving and the row driving technologies, as well as, FPGA control technology. In order to improve display result of the printable field emission display, the luminance non-uniformity correction method, gamma correction method and automatic power control method are proposed by theoretical analyzing and practical certificating. Image processing method is used into the driving circuit and image luminance uniformity and gray-scale reproduction quality are improved, the sample power consume is also reduced. At present, the technology has been used in the 25 inch color low work function printable FED sample fabricated with the capacity for image processing in our lab. It can display color video images and the obtained brightness is about 400 cd/m^2 ,contrast ratio 1 000：1 and 256 circuit gray scales.