High efficiency dimmable cold cathode fluorescent lamp ballast
AssigneePhilips Electronics North America Corporation
InventorsPawel M. Gradzki, Wen-Jian Gu, Ihor T. Wacyk
Life of this patent
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Abstract
A ballast including an inverter and a circuit having a resonant frequency coupled to the output of the inverter. In one embodiment of the invention, the only discrete type of element substantially affecting the resonant frequency is substantially inductive in electrical character. In this embodiment of the invention, there is also no discrete ballasting element in series with the lamp load. The reduction in discrete elements reduces both power consumption and costs associated with the ballast.
Claims24
A ballast, comprising:
- a switching stage having an output;
- and
- a circuit having a resonant frequency and coupled to the output of the switching stage;
- wherein the only type of discrete element within the circuit substantially affecting the resonant frequency thereof is substantially inductive in electrical character.
A ballast, comprising:
- a switching stage;
- a circuit coupled to the switching stage, having a resonant frequency and including a serial combination of an inductor, a first capacitor and a primary winding of a transformer, that portion of the serial combination formed by the first capacitor and primary winding being in parallel with a second capacitor;
- and
- a lamp load coupled to a secondary winding of the transformer;
- wherein the only discrete elements of the circuit substantially affecting the resonant frequency are the inductor and second capacitor.
A method of ballasting a lamp load, comprising the steps of:
- generating a varying DC voltage;
- and
- applying the varying DC voltage to a circuit having a resonant frequency wherein the only type of discrete element within the circuit substantially affecting the resonant frequency is substantially inductive in electrical character.
A ballast circuit for a discharge lamp comprising:
- input terminals for supplying an operating voltage to the ballast circuit,
- a transistor switching stage coupled to the input terminals and operative at a high frequency,
- a circuit having a resonant frequency corresponding to the switching stage high frequency and coupled to an output of the switching stage, said circuit including a transformer having leakage inductance and parasitic capacitance, wherein the resonant frequency of the circuit is determined substantially only by said leakage inductance and said parasitic capacitance.
Dependencies are inferred from the claim text.