Fluorescent lamp with opposing inversere cone electrodes
AssigneeGeneral Electric Company
InventorHarald L. Witting
Life of this patent
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Abstract
Electrodes for high current electric discharges in low pressure gases comprise a heated filament, coated with emissive material and surrounded by a hollow emitting surface in the shape of a truncated cone. The electric discharge initially starts from a spot on the filament and transfers to a diffuse mode at the small end of the cone structure. High current fluorescent lamps which include the electrodes of the present invention are characterized by rapid transition from the spot mode to the diffuse mode discharge and by low cathode fall voltage.
Claims14
In an electrode structure, which includes an improved cathode for an electric discharge emanating from substantially a single direction, comprising:
- a refractory metal cylinder, open at both ends and having inner and outer surfaces;
- and
- an emissive mix coated filament centrally disposed within said cylinder;
- the improvement wherein
- said cylinder comprises a truncated conical structure having a wide end and a narrow end with the narrow end thereof directed toward the electric discharge, whereby a transition, from a termination of the electric discharge on the filament, to a termination of the electric discharge on the cylinder, is hastened.
A fluorescent lamp comprising:
- a substantially tubular, light-transmissive, evacuable envelope having two ends;
- a fill gas contained within said envelope;
- at least one electrode structure disposed at each end of said envelope, said electrode structure comprising a truncated conical, refractory metal cylinder open at both ends and having a wide end and a narrow end with the narrow end directed substantially toward the end of said tubular envelope opposite that end in which said electrode structure is disposed, said electrode structure also possessing an emission mix coated filament centrally disposed within said cylinder;
- and
- means for establishing and maintaining an electric discharge between said electrode structures.
Dependencies are inferred from the claim text.