Electrodeless fluorescent lamp dimming system

Details Electrodeless fluorescent lamp dimming system Electrodeless fluorescent lamp dimming system

1999-05-25

2001-01-16

Philogene, Haissa (Department: 2821)

Electric lamp and discharge devices: systems

Current and/or voltage regulation

C224S201000, C224S248000, C224S243000

Reexamination Certificate

active

06175198

ABSTRACT:

FIELD OF INVENTION
The present invention relates to a ballast, or power supply circuit, for electrodeless fluorescent lamps of the type using regenerative gate drive circuitry to control a pair of serially connected complimentary conduction-type switches of a d.c.-to-a.c. converter. More particularly, the invention relates to a dimmable system of the ballast which allows dimming control of the fluorescent lamp.
BACKGROUND OF THE INVENTION
U.S. Pat. No. 5,796,214, U.S. Ser. No. 08/709,062, filed on Sep. 6, 1996 and U.S. Ser. No. 08/897,435, filed Jul. 21, 1997 all by the present inventor, discloses and claim ballasts for an electrodeless lamp. The ballasts include a d.c.-to-a.c. converter formed of a pair of serially connected switches having opposite conduction modes. For instance, one switch may be an n-channel enhancement mode MOSFET, and the other a p-channel enhancement mode MOSFET, with their sources interconnected at a common node. This allows a single control voltage applied to the gates, or control nodes, of the MOSFETS to alternately switch on one MOSFET and then the other. The foregoing ballasts allow the lamp to be in either an “on” state or an “off” state, but does not provide a matter of dimming the electrodeless lamp.
In existing electrode lamps, conventional methods continuously change the frequency of oscillation to control the amount of current flowing through an arc, and therefore the lumens output from the lamp. Attempting to apply this concept to electrodeless fluorescent lamp systems would result in overheating of the r.f. coil and the ballast switches. Additionally, conventional dimming methods will not produce a sufficient h-field to sustain a toroidal discharge when the arc current is reduced to less than 50% of rating. As the arc current decreases, the h-field decreases and the azimuthal e-field increases, causing the toroidal arc to extinguish and a longitudinal glow discharge to continue.
It would be desirable to provide a ballast, for an electrodeless lamp, which incorporates a dimming circuit to allow a range of dimming control for an electrodeless lamp.
SUMMARY OF THE INVENTION
An exemplary embodiment of the invention provides a ballast for an electrodeless gas discharge lamp. The ballast includes a load circuit having a r.f. inductor for generating an r.f. field to power the electrodeless lamp, in a resonant capacitance inductance network. A d.c.-to-a.c. converter circuit is coupled to the load circuit for inducing a.c. current therein to be used by the r.f. inductor. A dimming circuit, which uses frequency shift keying (FSK), is coupled to a drive circuit of the ballast. The dimming circuit is comprised of a secondary mutually coupled dimming inductor, serially connected dimming switches, and a signal generator. The frequency shift keying (FSK) shunts the voltage of the coupled secondary inductor when a pulse is applied to the gates of the dimming switches. When the pulse is applied to the gates of the dimming switches, frequency of the ballast is shifted to a higher level causing the r.f. inductor current to decrease, extinguishing the arc of the electrodeless lamp. By modulating operation of the dimming switches, the average power and therefore the average lumen output of the electrodeless lamp can be controlled.


REFERENCES:
patent: 4189661 (1980-02-01), Haugsjaa et al.
patent: 4249111 (1981-02-01), Gluck
patent: 4382212 (1983-05-01), Bay
patent: 4680508 (1987-07-01), Rucki
patent: 5173643 (1992-12-01), Sullivan et al.
patent: 5245253 (1993-09-01), Quazi
patent: 5291100 (1994-03-01), Wood
patent: 5315214 (1994-05-01), Lesea
patent: 5373217 (1994-12-01), Gregor
patent: 5561351 (1996-10-01), Vrionis et al.
patent: 5744912 (1998-04-01), So
patent: 5796214 (1998-08-01), Nerone
patent: 5825130 (1998-10-01), Nerone et al.
patent: 5841239 (1998-11-01), Sullivan et al.
patent: 5850127 (1998-12-01), Zhu et al.
patent: 5864212 (1999-01-01), Sullivan
patent: 5874810 (1999-02-01), Nerone
patent: 5877595 (1999-03-01), Nerone
patent: 5965985 (1999-10-01), Nerone

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