A protecting layer for the dielectric in AC plasma panels

One of the important problems in the development of ac plasma panels is to produce panels that maintain stable characteristics for a long time. A new idea for using a protecting layer over the dielectric layer which isolates the electrodes from the gas was examined and good results were obtained. Moreover, besides stability, a considerable improvement of operating characteristics was achieved, including low-voltage operation capability. Sputtering of the protecting layer, which is thought to govern the life of plasma panels, occurs even to heat-resisting oxides of large binding energy, but the sputtering rate appears to be so slow that it hardly affects the panel life. Also, the rate of decomposition accompanying sputtering is small. The problem of cracks in the protecting layer, which is the cause of defective life characteristics in such respects as migration of the lead component of the dielectric layer onto the protecting layer and the direct exposure of the dielectric-layer glass to the discharge, was solved by process-technique improvements. This paper describes the merit of using a protecting layer, required performance for this layer, and experimental results, and discusses voltage stability and the results of selection of materials for it.