Tapered helical compact fluorescent lamp

Claim 1

An electric discharge lamp comprising: an evacuable envelope including inner and outer glass members of tapered cylindrical shape in nested coaxial relationship, at least one of said members having a helically-shaped channel therein for providing an electrical discharge path; said channel characterized by a non-uniform pitch around the circumference of said cylindrical member wherein the helix angle of said channel is a minimum where the channel crosses a vertical plane passing through said envelope and is a maximum at 90* to said plane, thereby providing an asymmetric helically-shaped channel; a pair of electrodes, one disposed adjacent each end of said channel and supported by at least one of said glass members; a luminescent material covering the interior walls of said glass members at least along said discharge path, the luminescent material covering the interior wall of said inner glass member being thicker than the luminescent material covering the interior wall of said outer glass member; ballast means electrically connected to said electrodes for regulating electric current flow along said discharge path, said ballast means positioned within the opening defined by said inner glass member; means including a screw-in base for providing said electric current to said ballast means; means sealing together the ends of said inner and outer glass members; and a gaseous filling in said discharge path.