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AssigneeKoninklijke Philips Electronics N.V.
InventorsGuenther Hans Derra, Hanns Ernst Fischer, Dieter Leers, Holger Moench
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A high-pressure gas discharge lamp (HID or UHP lamp, or in general lamps with mercury fillings of between approximately 0.05 and 0.5 mg/mm3) is described with at least one electrode (7, 8) which is provided with a thickened, for example globular portion (9, 10) at its end lying inside a lamp vessel (2). This portion is so dimensioned in dependence on operational parameters of the lamp and/or the diameter of the electrode rod that an electrode tip (19) forms itself independently at said portion during the first hours of operation. This tip grows from the portion until its free end starts melting. The electrode tip is self-adjusting in this manner, so that an optimum electrode interspacing is maintained throughout lamp life. Furthermore, a method of manufacturing such a lamp is described.
A high-pressure gas discharge lamp with at least one electrode having an electrode rod which comprises a thickened electrode portion at one end, characterized in that the thickened electrode portion (9, 10) is dimensioned in dependence on operational parameters of the lamp such that said thickened portion does not melt during normal lamp operation, but that an electrode tip (19) forms itself at the electrode portion (9, 10) during the first hours of operation of the lamp until said tip (19) melts in the region of the point of application of a light arc.
A method of manufacturing a high-pressure gas discharge lamp, characterized in that, for the manufacture of the electrode, an electrode rod is provided with a thickened portion (9, 10) at one end, and an electrode tip (19) is formed at this portion (9, 10) during the first hours of operation of the lamp by means of a current which corresponds substantially to the operational current of the lamp, during which the thickened portion is dimensioned in dependence on said current.
Dependencies are inferred from the claim text.