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Circuit apparatus and method for operating a lamp

  • US 7,053,561 B2
  • Filed: 07/23/2003
  • Issued: 05/30/2006
  • Est. Priority Date: 08/01/2002
  • Status: Active Grant
First Claim
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1. A circuit for operating a discharge lamp (LA), the circuit comprising:

  • an inverter (T1,T2) for supplying the lamp with alternating current, the inverter having an operating frequency, the inverter comprising;

    at least one transistor switching unit (T2) having a gate; and

    a current limiting device (T3,D1,D2,D3,C3) coupled to the gate of the at least one transistor switching unit (T2), wherein the current limiting device is operable to switch the at least one transistor unit on and off as a function of a current flowing through the at least one transistor unit;

    a load circuit (L1-A,C1,C2) connected between the inverter and the lamp, the load circuit having a resonant frequency; and

    a phase setting device (R2,C2,L2) connected to the gate of the at least one transistor switching unit (T2), the phase setting device being operable to match the operating frequency of the inverter to the resonant frequency of the load circuit.

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