RF induction lamp with reduced electromagnetic interference

• US 8,698,413 B1
• Filed: 11/26/2012
• Issued: 04/15/2014
• Est. Priority Date: 11/26/2012
• Status: Active Grant

• Current Assignee: Lucidity Lights, Inc.
• Original Assignee: Lucidity Lights, Inc.
• Inventors: Godyak, Valery A., Maya, Jakob, Lester, James N.
• Primary Examiner(s): PHILOGENE, HAISSA
• Application Number:
  US13/684,665
• Time in Patent Office: 505 Days
• Field of Search: 315/248, 315/267, 315/278, 315/344, 315/291, 315/246, 315/285, 315 56- 58, 315/61, 315/62, 313/34, 313/484, 313/485, 313/493, 313/571, 313/576
• US Class Current: 315/248
• CPC Class Codes: H05B 41/2806 with semiconductor devices and specially adapted for lamps without electrodes in the vessel, e.g. surface discharge lamps, electrodeless discharge lamps
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

An induction RF fluorescent lamp configuration provides reduced EMI, including a lamp envelope with a re-entrant cavity both covered on the partial vacuum side with phosphor and filled with a working gas mixture, a tubular ferromagnetic core on the non-vacuum side said re-entrant cavity wound directly on the said core with two windings having different numbers of turns, a first active winding having one end connected to an RF ballast and the other end connected to local ground, and a second passive winding having one end grounded and the other end free.

Claims

1. An induction radio frequency (RF) fluorescent lamp, comprising:

a lamp envelope with a re-entrant cavity both covered on a partial vacuum side with phosphor and filled with a working gas mixture;

a tubular ferromagnetic core on a non-vacuum side of said re-entrant cavity, wherein one or more radial spacers support the tubular ferromagnetic core to be axial to the re-entrant cavity with a fixed air gap between them;

two windings on said tubular ferromagnetic core having a different number of turns, a first winding being an active winding having one end connected to an RF ballast and the other end connected to local ground and a second winding being a passive winding having one end grounded and the other end free.

2. The lamp of claim 1, wherein the one or more spacers are made of a high temperature resistant material having a melting point of approximately 150 C. or higher.

3. The lamp of claim 1, wherein a top spacer and a bottom spacer are of different shapes.

4. The lamp of claim 1, wherein a top spacer and a bottom spacer are of different materials.

5. The lamp of claim 1 wherein a separation between the windings and the non-vacuum side of the re-entrant cavity wall is in the range from approximately 0.1 mm to 1.5 mm.

6. The lamp of claim 1, wherein the RF end of the first winding connecting it to the ballast is adjacent to and between the grounded ends of both windings.