Dopant-free tungsten electrodes in metal halide lamps
AssigneeAdvanced Lighting Technologies, Inc.
InventorsChakrapani V. Varanasi, Timothy R. Brumleve, Abbas Lamouri, Ajaypal Naruka
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Abstract
A metal halide lamp having a high pressure quartz arc tube in which the electrodes are non-thoriated.
Claims20
A metal halide lamp having a base, an outer envelope, and a quartz arc tube, said arc tube having un-doped tungsten electrodes and a lamp fill material containing scandium metal, a thorium halide, and at least one halide of a metal within the group comprising scandium and rare earth metals at an operating pressure of at least 30 torr.
A metal halide lamp having a base, an outer envelope, and a quartz arc tube, said arc tube having un-doped tungsten electrodes and a lamp fill material containing scandium metal and at least one halide of a metal within the group comprising scandium and rare earth metals at an operating pressure of at least 30 torr;
- wherein the lamp fill material includes sodium, scandium, and thorium.
An arc tube for a metal halide lamp comprising:
- a quartz arc tube envelope;
- two un-doped tungsten electrodes extending into said arc tube envelope from which an electric arc may be struck;
- and
- lamp fill material disposed interiorly of said arc tube envelope containing scandium metal, a thorium halide, and at least one halide of a metal from the group consisting of scandium and rare earth metals at an operating pressure of at least 30 torr.
An arc tube for a metal halide lamp comprising:
- a quartz arc tube envelope;
- two un-doped tungsten electrodes extending into said arc tube envelope from which an electric arc may be struck;
- and
- lamp fill material disposed interiorly of said arc tube envelope containing scandium metal and at least one halide of a metal from the group consisting of scandium and rare earth metals at an operating pressure of at least 30 torr;
- wherein the lamp fill material includes sodium, scandium, and thorium.
A quartz arc tube for a high pressure metal halide lamp in which the electrodes are essentially free of thorium and in which the lamp fill material contains halides of sodium, thorium and scandium and excess scandium.
A lamp comprising:
- a quartz arc tube;
- a pair of non-thoriated tungsten electrodes;
- and
- a fill material comprising scandium metal and a thorium halide.
A quartz arc tube for a high pressure metal halide lamp comprising:
- un-doped tungsten electrodes;
- and
- lamp fill material including halides of sodium, thorium and scandium and excess scandium, wherein the operating voltage increases less than about 4% over 5,000 operating hours.
Dependencies are inferred from the claim text.