High pressure metal halide lamp
AssigneeU.S. Philips Corporation
InventorGhaleb Natour
Life of this patent
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Abstract
A light transmitting discharge vessel encloses a discharge space, sealed in a gas-tight manner, in which electrodes connected to current conductors which extend to the exterior are disposed. A filling in the discharge vessel comprises a rare gas, a buffer gas and at least one transition metal halide chosen from the halides of hafnium, zirconium and tantalum. Each of the electrodes comprises an electrode part containing a carbide chosen from the carbides of hafnium, zirconium and tantalum. As a result diffusion of transition metal from the plasma into the electrode is strongly suppressed so that the lamp keeps very good color rendering properties throughout its operation.
Claims12
A high pressure metal halide lamp comprising
- a light transmitting discharge vessel enclosing a discharge space, sealed in a gas-tight manner, in which electrodes are disposed, which electrodes are connected to current conductors which extend to the exterior, each electrode comprising a first electrode part in said discharge space,
- a filling in the discharge vessel comprising a rare gas, a buffer gas and at least one transition metal halide chosen from the halides of hafnium, zirconium and tantalum, wherein each said first electrode part contains a carbide chosen from the carbides of hafnium, zirconium and tantalum.
Dependencies are inferred from the claim text.