Tungsten halogen incandescent lamp with arc preventing fill
AssigneeThorn EMI plc
InventorsIan Connor, Roger A. Hume
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Abstract
A tungsten halogen incandescent filament lamp is provided having a fill of inert gas and halogen. In such lamps and especially in lamps provided for studio and theatre applications having operating temperatures between 2200K and 3450K there is a tendency to arc over between the filament limbs. According to the invention this problem can be solved by adding hydrogen gas in an amount between 0.05% and 1% by pressure at 20.degree. C. This hydrogen gas is in addition to any hydrogen which is present as part of the halogen or halogens. A preferred halogen is the solid hydrogen, bromophosphonitrile (PN Br.sub.2).sub.n which introduces phosphorus as a getter into the lamp.
Claims7
A tungsten halogen electric incandescent filament lamp comprising a lamp envelope of quartz material having a fill comprising halogen and an inert gas, the halogen being present in a range to provide between 2 microgrammes per milliliter and 70 microgrammes per milliliter of halogen and the inert gas being present at a filling pressure between 0.5 and 5 atmospheres at 20.degree. C., and in addition to any hydrogen present as part of the halogen there is included hydrogen gas in the quantity between 0.05% and 1% by pressure at 20.degree. C. whereby sufficient hydrogen is retained within the quartz envelope to prevent arcing.
Dependencies are inferred from the claim text.