Patent US4555632A successfully refreshed from Google Patents.
US5173643A
Expired / Lapsed
US
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Circuit for dimming compact fluorescent lamps
Assignee: Lutron Technology Co LLC
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Filing: 1990-06-25
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Granted: 1992-12-22
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Expires: 2010-06-25
Abstract
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.
Inventors
- 👤 Charles R. Sullivan
- 👤 Scott R. Jurell
- 👤 David G. Luchaco
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 05:35
CPC Classifications
H; H05; H05B; H05B41/00; H05B41/14; H05B41/36; H05B41/38; H05B41/39; H05B41/392; H05B41/3921; H05B41/3927; H05B41/26; H05B41/28; H05B41/282; H05B41/285; H05B41/2851; H02; H02M; H02M1/00; H02M1/32; H02M1/34; H02M1/346; Y; Y02; Y02B; Y02B20/00; Y02B70/00; Y02B70/10; Y10; Y10S; Y10S315/00; Y10S315/04; Y10S315/07
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
123 words
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.
Claim 2
Dependent Claim
123 words
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.
Claim 3
Dependent Claim
33 words
The electromagnetic circuit as recited in claim 1 wherein the number of turns of said secondary winding to the number of turns of said primary winding is in a ratio of approximately 6:1.
Claim 4
Dependent Claim
37 words
The electromagnetic circuit as recited in claim 2 wherein the number of turns of said first portion to the number of turns of said second portion of said secondary winding is in a ratio of approximately 9:4.
Claim 5
Dependent Claim
26 words
The electromagnetic circuit as recited in claim 1 further comprising a current sensing circuit electrically connected between said first and second portions of said secondary winding.
Claim 6
Dependent Claim
28 words
The electromagnetic circuit as recited in claim 4 wherein said current sensing circuit comprises a resistor electrically connected between said first and second portions of said secondary winding.
Claim 7
Dependent Claim
52 words
The electromagnetic circuit as recited in claim 5 wherein said current sensing circuit further comprises a voltage breakover device in series with said resistor, and a second resistor in parallel with said breakover device such that current flow through said current sensing circuit produces a voltage thereacross having a dual slope characteristic.
Claim 8
Dependent Claim
34 words
The electromagnetic circuit as recited in claim 1 further comprising a capacitor electrically connected across one of said lamps to help balance the light output of said pair of lamps at low light levels.
Claim 9
Dependent Claim
32 words
The electromagnetic circuit as recited in claim 1 further comprising means for simultaneously providing a dc component of current flow between said lamp electrodes to substantially eliminate the occurrence of visible striations.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-12-22 | 1996-06-22 | 1996-12-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-12-22 | 2000-06-22 | 2000-12-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-12-22 | 2004-06-22 | 2004-12-22 | $7700.00 | Window Closed / Lapsed |