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US 2001/0033141 A1Published application
Switching device
AssigneeKoninklijke Philips Electronics N.V.
InventorsJohannes Hendrik Wessels, Melanie Maria Jeanne Anna Michon, Machiel Antonius Martinus Hendrix
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Abstract
An electronic ballast for operating a lamp with a high-frequency current is equipped with a load branch comprising two LC combinations. The LC combinations are dimensioned such that the shape of the high-frequency current is in between a sine shape and a square-wave shape. The efficacy of a lamp operated by means of the electronic ballast is high, while the RFI generated by the lamp is low.
Claims5
A switching device for energizing a lamp with a high-frequency lamp current at a frequency f, which switching device is provided with
- a first circuit part for generating a periodical, substantially square-wave voltage at a frequency f, which first circuit part is provided with output terminals,
- a load branch comprising
- a first branch, which interconnects the output terminals, and which comprises a first series arrangement of a first inductive element and a first capacitive element,
- a second branch, which shunts the first capacitive element, and which comprises a series arrangement of a second inductive element and a second capacitive element, and
- a third branch, which comprises lamp terminals, and which shunts the second capacitive element during operation of the lamp,
- characterized in that the first branch and the second branch are dimensioned such that, during lamp operation, the following relation is met
- 0.14<ΣA(n)/A(1)<0.42,
- wherein A(1) denotes the amplitude of the first harmonic component of the high-frequency lamp current, and Σ A(n) is the sum of the amplitudes of the higher harmonic components of the lamp current.
5 more elements
Dependencies are inferred from the claim text.