Various lighting systems have been developed using the dielectric barrier discharge (DBD) principle, where electrical power is coupled into a discharge chamber via a dielectric barrier. This barrier may be formed by a frit glass layer, covering at least one of the internal lamp electrodes. But also external electrodes are in use where the dielectric layer is simply given by the glass wall of the discharge vessel itself. In any case the dielectric barrier acts as a key component and strongly determines the properties of DBD light sources: Extremely long lamp lifetimes, Hat lamps in any size and shape or the ability of switching multiple DBD lamps in parallel are only a few special features which can be achieved by the dielectric barrier. On the other hand it is well known that the driving conditions of DBD lamps -especially mercury free ones- strongly influence the system performance and the ability to fit into specific applications. High lamp voltages with huge slew rates, good control flexibility, scalability to different power levels, synchronization to external clocks, power regulation, multiple safety circuits and cost issues often call for new ballast concepts.
展开▼
