Low-pressure mercury vapor discharge lamp with electrode shield
AssigneeU.S. Philips Corporation
InventorsCornelis R. Ronda, Cornelis J. M. Denissen, Volker U. Weiler, Wilhelm A. Groen, Wilhelmus M. P. Van Kemenade, Bennie J. De Maagt
Life of this patent
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Abstract
A low-pressure mercury vapor discharge lamp is provided with a discharge vessel and a first and a second end portion (12a). The discharge vessel encloses a discharge space provided with a filling of mercury and a rare gas in a gastight manner. Each end portion (12a) supports an electrode (20a) arranged in the discharge space. An electrode shield (22a) encompasses the electrodes (20a) and is covered with a material which reacts with or forms an alloy with alkaline earth metals, which material is released by the electrode (20a).
Claims18
A low-pressure mercury vapor discharge lamp comprising:
- a discharge vessel which encloses a discharge space provided with a filling of mercury and a noble gas in a gastight manner,
- a pair of electrodes arranged in the discharge space for generating and maintaining a discharge in the discharge space, at least one of the pair of electrodes comprising an alkaline earth metal which, in operation, is partly liberated, and
- an electrode shield at least substantially surrounding at least one of the pair of electrodes,
- wherein the electrode shield includes a material which reacts with or forms an alloy with the alkaline earth metal originating from the at least one of the pair of electrodes,
- wherein the material of the electrode shield comprises an oxide of another material which is nobler than the alkaline earth metal, said alkaline earth metal being barium or strontium and the oxide is selected from a group formed by copper oxide and iron oxide.
A discharge lamp comprising:
- a discharge vessel which encloses a discharge space filled with mercury and a noble gas;
- an electrode to generate a discharge in the discharge space, said electrode comprising an alkaline earth metal element in element form;
- and
- a shield which substantially surrounds said electrode;
- wherein said shield includes a material which reacts with or forms an alloy with the alkaline earth metal element.
Dependencies are inferred from the claim text.