Patent ID: 7911121
Filing Date: 2011-03-22
Classification: H01K

Abstract:
1. An incandescent lamp having an illuminant which contains a high-temperature resistant metal compound and having electrodes which hold the illuminant, the illuminant being introduced vacuum-tightly together with a filling in a bulb, the material of the illuminant comprising a metal or a metal compound, in particular a metal carbide, whose melting point lies close to the melting point of tungsten, at least at 3000° C., wherein the illuminant contains a material which becomes depleted of at least one chemical element owing to chemical decomposition and/or evaporation during operation, and in that a source and sink for this element are fitted in the bulb, the source delivering the element of which the illuminant is depleted and the element which the illuminant emits progressively during the lifetime being deposited on the sink, with the aid of a transport medium, so that overall there is a continuous flux of the described element from the source to the sink, the concentration of the relevant element being essentially steady at any position in the lamp, apart from startup processes, the illuminant in steady-state operation being in equilibrium with the partial atmosphere of the element constantly transported past it, imposed from the outside by the interaction of the source and sink, so that the illuminant is prevented from being depleted of the element in question, wherein the metal compound is a metal carbide, for example tantalum carbide, zirconium carbide or hafnium carbide or alloys of different metal carbides, and wherein the source consists of a graphite body, in particular graphite fibers, coated with the corresponding metal carbide, the carbon being transported to the sink by material additionally introduced as a constituent of the filling, from the group hydrogen and/or halogen, this material reacting in cooler regions with the carbon to form hydrocarbons or halogenated hydrocarbons, this hydrocarbon decomposing again at the sink while depositing carbon and releasing the transport medium.