The Theoretic Investigation Of The Discharge Characteristics Of Shadow Mask Plasma Display Panel

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.