Electric lamp and discharge devices: systems – Periodic switch in the supply circuit – Silicon controlled rectifier ignition
Patent
1996-12-09
1998-02-17
Pascal, Robert
Electric lamp and discharge devices: systems
Periodic switch in the supply circuit
Silicon controlled rectifier ignition
315200R, 315362, 315307, 315DIG4, H05B 3702
Patent
active
057194718
ABSTRACT:
A ballast for a gas discharge lamp comprises a resonant load circuit including a gas discharge lamp, and a resonant inductance and a resonant capacitance whose values determine the operating frequency of the remnant load circuit. A d.c.-to-a.c. converter circuit is coupled to the remnant load circuit to provide a.c. current to the remnant load circuit. The converter comprises at least one switch. A high voltage IC drives the at least one switch at a frequency determined at least in part by impedance between a timing input and a ground. A circuit for supplying a d.c. voltage to the d.c.-to-a.c. converter includes (i) a supply path for d.c. current; (ii) first and second return paths for d.c. current; and (iii) an arrangement to selectively make the first return path operable alone, the second path operable alone, and the first and second paths operable together. First and second impedances are coupled between the timing input and the first and second return paths, respectively. A second, one-way current valve isolates the second impedance from the ground when the second current path is rendered inoperable. A first, one-way current valve isolates the first impedance from the ground when the first current path is rendered inoperable. A second, one-way current valve isolates the second impedance from the ground when the second current path is rendered inoperable. When the lamp comprises resistively heated cathodes, a cathode current-controlling, frequency-dependent impedance is preferably connected between the resistively heated cathodes.
REFERENCES:
patent: 4383204 (1983-05-01), Roberts
patent: 5309062 (1994-05-01), Perkins et al.
(Product Note), "Ballast IC Applications Information (IR2151): Pre-Heating a Lamp Filament Without a PTC Resistor," International Rectifier Corporation, Oct. 1994, three pages.
(Product Note), "L6569: High Voltage Half Bridge Driver with Oscillator," SGS-Thompson Microelectronics, Mar. 1996, six pages.
(Product Note), "Provisional Data Sheet on IR 2155 Self-Oscillating Power MOSFET/IGBT Gate Driver," International Rectifier, Aug., 1993, five pages, the IR2155 driver being functional similar to the IR2151 driver mentioned at p. 3 of the present specification.
General Electric Company
Hawranko George E.
Pascal Robert
Vu David
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