Circuit for dimming compact fluorescent lamps
First Claim
1. An electromagnetic circuit for providing power from an ac source to a pair of series connected gas discharge lamps mounted in a grounded fixture, comprising:
- (a) a ferromagnetic core;
(b) a primary winding having at least one turn electromagnetically coupled to said core and electrically connected to said ac source;
(c) a secondary winding having a plurality of turns electromagnetically coupled to said core and said primary winding and electrically connected across said pair of gas discharge lamps in series; and
(d) a center tap electrically dividing said secondary winding into first and second portions, said center tap being electrically connected to said grounded fixture;
whereby the electrical potentials of said lamps to a ground plane of said grounded fixture are approximately equal.
2 Assignments
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Accused Products
Abstract
A dimming control circuit provides power from an ac source to a compact fluorescent lamp. The circuit generally includes a resonant half-bridge inverter driven by a pulse-duration-modulated voltage, for providing a high-frequency ac voltage between the lamp electrodes. A combination inductive and capacitive snubber circuit reduces switching losses in the inverter and increases the efficiency of the dimming circuit. A low-voltage transformer connected across the resonant portion of the inverter provides voltage to heat the lamp filaments. The filament voltage is substantially constant over a range of pulse-durations providing a dimming range from about 100% to 1% of full light output. A power supply circuit having a power factor of about 0.95 provides both high-voltage and low-voltage dc power to the dimming circuit with minimal losses. A shutdown circuit is provided to shut off power to the lamp if the dimming circuit is miswired or a ground fault occurs.
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Citations
8 Claims
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1. An electromagnetic circuit for providing power from an ac source to a pair of series connected gas discharge lamps mounted in a grounded fixture, comprising:
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(a) a ferromagnetic core; (b) a primary winding having at least one turn electromagnetically coupled to said core and electrically connected to said ac source; (c) a secondary winding having a plurality of turns electromagnetically coupled to said core and said primary winding and electrically connected across said pair of gas discharge lamps in series; and (d) a center tap electrically dividing said secondary winding into first and second portions, said center tap being electrically connected to said grounded fixture; whereby the electrical potentials of said lamps to a ground plane of said grounded fixture are approximately equal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification