SEF Lamp dimming

• US 4,219,760 A
• Filed: 03/22/1979
• Issued: 08/26/1980
• Est. Priority Date: 03/22/1979
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Ferro, Armand P.
• Primary Examiner(s): Smith, Alfred E.
• Assistant Examiner(s): Roberts, Charles F.
• Application Number:
  US06/022,938
• Time in Patent Office: 523 Days
• Field of Search: 315/248, 315/57, 315/DIG. 4
• US Class Current: 315/248
• CPC Class Codes: H05B 41/3928 for high-pressure lamps, e.g. high-intensity discharge lamps, high-pressure mercury or sodium lamps
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
• CPC Class Codes: Y10S 315/04 Dimming circuit for fluorescent lamps

Abstract

Solenoidal electric field lamps are effectively dimmed with no loss in lamp efficiency by powering the lamps with high frequency current pulses and periodically interrupting the current pulses in a time ratio fashion in order to reduce the average power being supplied to the lamp. The lamp may be dimmed from 100 to 0 percent of full power in an efficient manner as long as the pulse interruption period is less than the plasma deionization time of the lamp.

Claims

1. A method of dimming an SEF lamp comprising:

applying current pulses to said lamp at a first frequency, l/T'"'"', and repeatedly interrupting said current pulses every l/T₁ seconds, said interruption lasting for a time, T₁ -T₀ seconds where T'"'"' is less than T₁ and T₀ is no greater than T₁.

2. The method fo claim 1 in which l/T'"'"' is greater than 25 KHz.

3. The method of claim 2 in which T₁ -T₀ is less than the plasma deionization period.

4. A dimmable SEF lamp apparatus comprising:

an SEF lamp including an evacuable, light-transmissive phosphor coated envelope containing an ionizable medium which is electromagnetically coupled through a toroidal ferrite core which is coupled to a source of radio frequency current pulses operating at a first frequency, l/T'"'"'; and

means for interrupting said current pulses every l/T₁ seconds for a time T₁ -T₀ seconds where T'"'"' is less than T₁ and T₀ is no greater than T₁.

5. The apparatus of claim 4 in which l/T₁ is greater than 25 KHz.

6. The apparatus of claim 5 in which T₁ -T₀ is less than the plasma deionization period.