Tapered helical compact fluorescent lamp

• US 3,899,712 A
• Filed: 05/01/1974
• Issued: 08/12/1975
• Est. Priority Date: 05/01/1974
• Status: Expired due to Term

• Current Assignee: Harald L. Witting
• Original Assignee: Harald L. Witting
• Inventors: Witting, Harald L.
• Primary Examiner(s): Demeo, Palmer C.
• Application Number:
  US05/465,901
• Time in Patent Office: 468 Days
• Field of Search: 313/220,493,204,317,487,318 315/59
• US Class Current: 313/493
• CPC Class Codes: H01J 61/33 Special shape of cross-section, e.g. for producing cool spot
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

An improved electric discharge lamp, such as a fluorescent lamp, is described in accord with one embodiment of the invention as comprising a tapered cylindrical envelope having a helicallyshaped channel of nonuniform pitch therein for providing a discharge path circumferentially around the envelope with a pair of electrodes disposed adjacent each end of the discharge path. Means are also disclosed for coating the interior surface of the envelope with a luminescent material and filling the envelope with an ionizable gas.

Claims

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.