【作者】 张健；

【导师】 尹涵春； 屠彦；

【作者基本信息】 东南大学 ， 物理电子学， 2005， 博士

【摘要】 等离子体显示技术(PDP)具有高亮度、高对比度、宽视角、色彩逼真等优点,是大屏幕高清晰度显示器的首选。但是,它仍然存在制造成本高,放电效率低等缺点。目前对PDP的研究主要集中在提高发光效率、提高分辨率、延长寿命等方面。由于PDP放电单元很小,实验研究很困难,并且无法直接测量放电过程中的粒子分布的变化,因此数值模拟的方法成为PDP研究的一个重要且有效方法。本论文主要是通过自行编制的软件,用数值模拟的方法,研究了影响荫罩式等离子显示屏(SM-PDP)的放电性能。首先基于二维流体模型基础上,完成了PDP三维模拟软件。流体模型主要包括粒子连续性方程和泊松方程。在利用数值计算的方法求解这两个方程时,为了克服方程求解过程中介电驰豫时间对时间步长的限制,本文采用了对粒子浓度预测的方式,使计算速度大大加快。同时为了保证计算的稳定性,本文在比较了多种粒子连续性方程的离散格式基础上,采用了指数格式,即保证了计算的稳定,又能获得较高的计算速度。在流体模型的基础上,本文首次使用表面电荷法与流体模型相结合,计算了PDP的放电电流,从而能更方便准确地研究放电过程中各参量的变化对放电电流的影响,并与实验测量结果进行比较。根据SM-PDP的特殊性,特别是25”SVGA SM-PDP的圆形像素单元,具有轴对称性,本文同时在直角坐标和轴对称坐标中,完成了公式的推导和程序开发。其次本文利用完成的模拟软件对SM-PDP的放电性能作了系统的分析并与传统的表面放电PDP进行了比较。研究了各结构参数、放电气体、驱动频率等因素对SM-PDP性能的影响。改变放电单元的结构,使放电空间的电场发生变化,从而使放电性能发生改变。提高放电气体中的氙的比例,可以提高所产生的氙谐振态粒子的数量,从而使放电效率提高;增加放电气体的压强,尽管放电气体的着火电压增高,但同时电子与其它粒子碰撞的几率增大,放电效率提高。驱动电压频率的升高,在相同的时间内放电次数增加,可以提高显示亮度,同时增大显示的灰度等级。通过与传统的表面放电PDP比较,可以看到SMPDP具有着火电压低、寻址时间短、亮度高、效率高等优点。与传统的PDP不同SM-PDP中障壁是金属等位体,可以通过调节荫罩上的电压,来改变放电空间的电场,以获得更好的放电性能。本文详细分析了荫罩上电压波形的不同对SM-PDP放电性能的影响,并在此基础上,设计了荫罩上的电压波形,使荫罩在放电过程中电位更接近外加的阳极电位,从而大大提高SM-PDP的放电性能。更多还原

【Abstract】 Plasma display panel (PDP) has many advantages, such as high luminance, high contrast, wide viewing angle and full color display. It has been regarded as one of the best candidates for HDTV (High-Definition Television). However, high cost and low efficacy of PDP still need to be improved. Today the study of PDP is mainly focused on high efficacy, high definition, long lifetime. Because the display cell of PDP is very small, the experiment at investigation is difficult and the distribution of particles can’t be measured directly in the progress of discharge. One powerful method is to simulate the discharge process by computer calculation. In this thesis, the discharge characteristics of PDP are analyzed by simulation method.First, on the basis of the 2-D fluid model, the 3-D simulation software has been developed. The fluid model includes the continuous equation of particles and Poisson equation, etc. In order to overcome the time step limitation determined by Courant-Friedrichs-Lewy (CFL) condition, the prediction method is used to determine the density of particles in the iteration formulae . The calculation velocity is improved greatly. At the same time, in order to keep the stability of calculation, the exponential scheme of Scharfetter and Gummel is employed, on the basis of comparison between several schemes. The surface charge method is combined with fluid model to simulate the discharge current in the discharge cell. The influence of discharge process to the discharge current can be investigated conveniently and accurately and it’s also easy to compare with the experimental results. Because of the cell structure of shadow mask PDP (SM-PDP), especially 25”SVGA SM-PDP, circular cell is used and it has the axial symmetric property. To save the calculation resource and time, not only the Descartes coordinate but also cylindrical coordinate can be used in our software and corresponding formulae are also deduced.Then, the discharge characteristics of SM-PDP cell are analyzed with the software. The effect of structure parameter, discharge gas and driving voltage frequency on the discharge characteristics is studied. The change of cell structure makes the electric field change in the discharge cell, so it can affect the discharge process. Because increasing the xenon content in discharge gas can produce more particles of resonant state xenon, the discharge efficiency can be improved too. Increasing the discharge gas pressure will make the firing voltage of PDP high. However, it will enhance the collision probability between electrons and other particles. The discharge efficiency will be improved. Increasing the frequency of driving voltage will increase the number of discharge in the same time. Then it can enhance the discharge luminance, and get more gray scales.It is different from the conventional PDP that the barrier ribs in SM-PDP are metal. Adjusting the voltage on the metal barrier ribs can change the electric field in discharge cell. By this method, the discharge characteristics can be improved. In this thesis, the characteristics of discharge cell with different voltage waveform on the metal barrier ribs are analyzed. On the basis of it, the driving voltage waveform on the barrier ribs is designed; there is a tendency that the voltage on the metal barrier ribs is better to approach the anode voltage. The discharge characteristics are improved greatly with the optimized voltage waveform.更多还原