Title:
DIMMABLE BALLAST FOR ELECTRODELESS FLUORESCENT LAMPS
Document Type and Number:
WIPO Patent Application WO2003032692
Kind Code:
A3
Abstract:
An apparatus for controlling the brightness of an electrodeless fluorescent lamp (10) excited by power supplied to a coil disposed in closed proximity to said lamp. The apparatus includes a dimming control unit (13) responsive to a brightness setting for the lamp that provides a PWM signal indicative of the brightness setting. An oscillator (12) is disposed for producing a first lamp drive voltage having a first frequency selected in response to a first state of the PWM signal and a second lamp drive voltage having a second frequency selected in response to a second state of the PWM signal. Accordingly, the first drive voltage turns on the lamp by transferring maximum power to the lamp and the second drive voltage turns off the lamp by transferring minimum power to the lamp.
Inventors:
BLANCHARD RANDALL D
Application Number:
PCT/US2002/030754
Publication Date:
July 10, 2003
Filing Date:
September 26, 2002
Export Citation:
Assignee:
NORTHROP GRUMMAN CORP (US)
International Classes:
H05B41/392; H05B41/42; (IPC1-7): H05B41/392
Domestic Patent References:
| WO2001026431A1 | 2001-04-12 |
Foreign References:
| GB2309344A | 1997-07-23 | |||
| EP0889677A2 | 1999-01-07 | |||
| US6246183B1 | 2001-06-12 | |||
| GB2316246A | 1998-02-18 | |||
| US5027041A | 1991-06-25 | |||
| US5493183A | 1996-02-20 | |||
| EP1056316A2 | 2000-11-29 | |||
| EP0572207A2 | 1993-12-01 |
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