A new layer system of anti-reflective coating for cathode ray tubes

A new anti-reflective (AR) coating system, using an absorbing layer, has been developed for cathode ray tubes (CRTs). Theoretical analysis has revealed that the basic system needs only two layers to achieve zero reflection throughout the visible region if an ideal absorbing layer and a transparent layer are combined. The conditions for realizing the ideal AR property with two-layer system has been derived by numerical calculations. TiNxOy was chosen as the actual absorbing layer, while SiO2 was chosen as the transparent layer. These choices an both based on theoretical and experimental considerations. The oxygen content in the TiNxOy film was found to play an important role on the AR properties, therefore a very thin (around 5 nm) SiNx, barrier layer was deposited on the TiNxOy layer to prevent the oxidization of the TiNxOy during the subsequent deposition of SiO2. The insertion of such a thin SiNx, layer was found to have almost no influence on the optical properties, therefore the system (Glass/TiNxOy/SiNx/SiO2) can be called as two-layer system with a barrier layer. The AR properties and the electromagnetic shielding property (i.e. the electrical conductivity) of the coating was almost the same as the conventional transparent multilayer system which needs more than twice as thick as this system. This coating has been successfully adapted to the panel glass for CRTs on an industrial scale.