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US 6,603,250 B2Granted
Cathode coating for thermionic arc discharge lamp cathodes
AssigneeOsram Sylvania Inc.
InventorJohn W. Shaffer
Life of this patent
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Abstract
An arc discharge lamp has an evacuated, electromagnetic-energy-transmissive envelope having therein an arc generating and sustaining medium. At least one thermionic, electron-emitting cathode is positioned within the envelope, and the cathode has an electron emissive coating thereon containing silicon carbide.
Claims6
An electron emissive coating for a thermionic cathode comprising:
- oxides of barium, calcium, strontium and zirconium and an effective amount of silicon carbide to increase electron emissivity of said coating.
A thermionic cathode comprising:
- a tungsten coil;
- and
- an electron emissive coating on said tungsten coil, said coating comprising oxides of barium, calcium, strontium and zirconium and an effective amount of silicon carbide to increase electron emissivity of said coating.
A thermionic cathode comprising:
- an electron emissive coating including oxides of barium, calcium, strontium and zirconium and an effective amount of silicon carbide to increase electron emissivity of said coating.
An arc discharge lamp comprising:
- an evacuated, electromagnetic-energy-transmissive envelope;
- an arc generating and sustaining medium within said envelope;
- and
- at least one thermionic, electron-emitting cathode within said envelope, said cathode having an electron emissive coating thereon containing oxides of barium, calcium, strontium and zirconium and an effective amount of silicon carbide to increase electron emissivity of said coating.
1 more element
Dependencies are inferred from the claim text.