High-pressure gas discharge lamp and electron emissive electrode structure therefor
AssigneeU.S. Philips Corporation
InventorJohannis De Kok
Life of this patent
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Abstract
A high-pressure gas discharge lamp having an electrode consisting of a support of a high-melting metal provided with an electron emissive material. The emissive material consists mainly of one or more oxidic compounds containing (a) at least one of the rare earth metal oxides, (b) alkaline earth metal oxide in a quantity of 0.66 to 4 mole per mole of rare earth oxide and (c) at least one of the oxides of tungsten and molybdenum in a quantity of 0.25 to 0.40 mole per mole of alkaline earth metal oxide, the alkaline earth metal oxide consisting of at least 25 mol.% of barium oxide.
Claims7
A high-pressure gas discharge lamp having a radiation transmissive envelope containing electrodes and an ionizable medium in which the discharge is maintained, at least one of the electrodes consisting of a support of a high-melting metal provided with an electron emissive material which contains an alkaline earth metal and at least one of the metals tungsten and molybdenum, characterized in that the electron emissive material mainly consists of at least one oxidic compound containing at least one of the rare earth metal oxides, alkaline earth metal oxide in a quantity of 0.66 to 4 mole per mole of rare earth metal oxide and at least one of the oxides of tungsten and molybdenum in a quantity of 0.25 to 0.40 mole per mole of alkaline earth metal oxide, the alkaline earth metal oxide consisting of at least 25 mol.% of barium oxide.
A method for producing a gas discharge lamp which comprises:
- providing a tungsten electrode support;
- providing a suspension on said support which contains 20 to 60 mol.% of at least one of the rare earth metal oxides, 40 to 80 mol.% of alkaline earth metal carbonate, in which at least 25 mol.% of the carbonate is barium carbonate and 0 to 10 mol.% of tungsten;
- subjecting said support and suspension to a heat treatment at a temperature of 1500.degree. to 2100.degree. C in an inert or reducing atmosphere;
- and then positioning said electrode support within a lamp envelope;
- and then providing an ionizable medium within said lamp envelope.
A method for producing a gas discharge lamp which comprises:
- providing a tungsten electrode support;
- providing a suspension on said support which contains 20 to 60 mol.% of at least one of the rare earth metal oxides, 40 to 80 mol.% of alkaline earth metal carbonate, in which at least 25 mol.% of the carbonate is barium carbonate and 0 to 10 mol.% of tungsten;
- positioning said electrode support within a lamp envelope;
- subjecting said support and suspension to a heat treatment at a temperature of 1500.degree. to 2100.degree. C in an inert or reducing atmosphere;
- and then providing an ionizable medium within said lamp envelope.
Dependencies are inferred from the claim text.