Capacitively coupled RF fluorescent lamp with RF magnetic enhancement

• US 5,381,073 A
• Filed: 06/29/1993
• Issued: 01/10/1995
• Est. Priority Date: 10/16/1992
• Status: Expired due to Fees

• Current Assignee: GTE Products Corporation (Ams-Osram AG)
• Original Assignee: GTE Products Corporation (Ams-Osram AG)
• Inventors: Alexsandrovich, Benjamin M., Godyak, Valery A., Piejak, Robert B.
• Primary Examiner(s): Pascal, Robert J.
• Assistant Examiner(s): Shingleton, Michael B.
• Application Number:
  US08/084,393
• Time in Patent Office: 560 Days
• Field of Search: 313/493, 313/634, 315/248, 315/57, 315/58, 315/70, 315/71, 315/246, 315/261, 315/39, 315/34
• US Class Current: 315/58
• CPC Class Codes: H01J 61/54 Igniting arrangements, e.g. promoting ionisation for starting
• CPC Class Codes: H01J 61/56 One or more circuit elements structurally associated with the lamp
• CPC Class Codes: H01J 65/046 the field being produced by using capacitive means around the vessel
• CPC Class Codes: H01J 65/048 the field being produced by using an excitation coil
• CPC Class Codes: H05B 41/24 in which the lamp is fed by high frequency ac, or with separate oscillator frequencyH05B41/26 takes precedence
• 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

A fluorescent light source includes a fluorescent lamp having first and second electrodes at or near the ends thereof for capacitive coupling of RF electrical energy to a low pressure discharge within the fluorescent lamp and an RF source having a first output lead electrically coupled to the first electrode and a second output lead electrically coupled to the second electrode. The electrodes include circuitry for inducing an RF magnetic field within the fluorescent lamp in the region of the electrodes. The RF magnetic field improves the performance of the capacitively coupled RF light source by creating an auxiliary inductive RF discharge near the capacitive coupling electrodes. The inductive discharge locally increases the plasma density and the electrode sheath capacitance and provides a reduction in RF voltage across the capacitively coupled fluorescent lamp.

Claims

1. A fluorescent light source comprising:

a fluorescent lamp including an envelope having two straight tube sections separated from each other and an interconnection between said straight tube sections at or near one end, first and second electrodes located adjacent to each other at or near the other end thereof for capacitively coupling of RF electrical energy to a low pressure discharge within said fluorescent lamp, each of said first and second electrodes each comprising a cold cathode electrode located within said fluorescent lamp;

starting means for initiating a low pressure discharge within said fluorescent lamp comprising a high permittivity dielectric material between said straight separated tube sections and confined to an area adjacent to said first and second electrodes; and

an RF source having a first output lead electrically coupled to said first electrode and a second output lead electrically coupled to said second electrode.

2. The fluorescent light source of claim 1 wherein said high permittivity dielectric material is glass.