Compact fluorescent lamp with improved power factor
AssigneeNorth American Philips Corporation
InventorJohn M. Wong
Life of this patent
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Abstract
A compact fluorescent lamp in combination with a high frequency DC-AC converter includes a rectifier circuit and a buffer capacitor coupled between a source of low frequency AC voltage and the converter. A feedback capacitor couples a high frequency feedback signal corresponding to the converter output signal to the buffer capacitor via the rectifier circuit so as to improve the power factor of the combination.
Claims25
In combination, a compact fluorescent lamp with a high frequency DC-AC converter, said converter including a pair of AC input terminals for coupling to a low frequency mains source of AC voltage, said AC input terminals having rectifying means coupled across them, said converter including two switching elements for switching current through said lamp during operation thereof at said high frequency, said switching elements being connected across said rectifying means, said rectifying means having a first junction point, a first capacitor connected to said first junction point, a pair of capacitors with a second junction point therebetween, said pair of capacitors being coupled across said rectifying means, a first inductor connected to said second junction point, said first capacitor and said first inductor being coupled to said AC input terminals.
In combination, a discharge lamp and a high frequency DC-AC converter, said converter including a pair of AC input terminals for coupling to a low frequency mains source of AC voltage, said AC input terminals having rectifying means coupled across them, said converter including two switching elements for switching current through said lamp during operation thereof at said high frequency, said switching elements being connected across said rectifying means, said rectifying means having a pair of diagonal terminals, a first capacitor connected to one terminal of said pair of diagonal terminals, a first inductor connected to the other terminal of said pair of diagonal terminals, means coupling said first capacitor and said first inductor to said AC input terminals, and a second capacitor coupling said discharge lamp to one of said diagonal terminals so that a high frequency current flows through the second capacitor to said one diagonal terminal.
A high frequency converter for operating an electric discharge lamp comprising:
- a pair of AC input terminals for connection to a low frequency source of AC supply voltage,
- first and second DC supply voltage input terminals,
- a rectifier circuit coupling said AC input terminals to said DC input terminals,
- buffer capacitor means coupled to said DC input terminals,
- a load circuit for connection to the discharge lamp,
- first and second switching transistors coupled to said DC input lines and to said load circuit and controlled so as to alternately switch current through the lamp at a high frequency,
- a first inductor coupled to one of said AC input terminals and to said buffer capacitor means, and
- a first capacitor coupling said load circuit to said buffer capacitor means via said rectifier circuit so as to couple a high frequency current to said buffer capacitor means from said load circuit.
A converter comprising:
- input means for receiving an AC voltage,
- inverter means for producing an output signal,
- a rectifier circuit having an input coupled to said input means and an output coupled to said inverter means, and
- feedback means for coupling a feedback signal indicative of said output signal to said input of the rectifier circuit.
Dependencies are inferred from the claim text.