AN ELECTROLUMINESCENT DISPLAY SIMULATION SYSTEM AND ITS APPLICATION FOR DEVELOPING GRAY-SCALE DRIVING METHODS

A simulation system has been developed for thin film alternative curre nt driven electroluminescent displays- The model embraces the whole di splay unit: the luminating panel, the row and column drivers and the p ulse generator circuits. An electro-analog model is constructed for th e luminating element and the luminating matrix panel. Macromodels suit able fer system simulations have been developed for the drivers and Pa rameters for them have been extracted from actual integrated driver ci rcuit processes. The pulse generators have been modeled mainly by util izing standard circuit simulator component models. The system was veri fied by simulating on-off type displays and comparing the results with measured ones. The simulation system was then applied for studying va rious proposed grey scale driving methods for thin film electrolumines cent displays. It was found that with present display manufacturing pa rameters most driving methods do not provide more than 16 levels with acceptable accuracy. It is concluded that the way to a higher number o f levels is either in the reduction of the electrode time constants or in developing more sophisticated grey scale driving schemes. A new ad vanced current mode driving schema was developed to overcome the probl ems of the basic methods. In simulations the new schema showed good pe rformance and accuracy for up to 64 levels.