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US 5,844,380 AGranted
Circuit arrangement for ingniting and supplying power to a lamp
AssigneeU.S. Philips Corporation
InventorRonald Siepkes
Life of this patent
Estimating the term…
Abstract
A circuit arrangement for igniting and supplying a discharge lamp by means of a substantially square-wave voltage at a frequency f1. It is possible to dim the lamp by adjusting the frequency of the substantially square-wave voltage to a value f2 which is different from f1. A protection circuit prevents damage to the lamp and to the circuit arrangement if the lamp current does not flow any more at the frequency f2.
Claims10
A circuit arrangement for igniting and supplying a lamp, comprising:
- a DC-AC converter for generating a substantially square-wave AC voltage at a frequency f1 from a supply voltage, the DC-AC converter including
- input terminals for connection to a supply voltage source,
- a first branch comprising a switching element which interconnects the input terminals, and
- a control circuit coupled to a control electrode of the switching element and provided with means I for generating a first control signal for rendering the switching element conducting and non-conducting at the frequency f1, and
- a load branch coupled to the DC-AC converter and including an inductive element, a capacitive element, and terminals for holding a lamp, the resonance frequency of the load branch being chosen so as to lie in the range between nf1 and (n+1)f1, where n is an even integer,
- wherein the control circuit further comprises means II for generating a second control signal for rendering the switching element conducting and non-conducting at a frequency f2, and means III for deactivating the means II and activating the means I dependent upon the operational condition of the lamp.
3 more elements
Dependencies are inferred from the claim text.