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Parallel-resonant inverter-type fluorescent lamp ballast

DC
  • US 6,472,827 B1
  • Filed: 03/18/1993
  • Issued: 10/29/2002
  • Est. Priority Date: 10/05/1984
  • Status: Expired due to Fees
First Claim
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1. An arrangement comprising:

  • an ordinary electric utility AC power line operable to provide an AC power line voltage at a pair of AC power line terminals;

    a voltage conditioning circuit having a set of AC input terminals drawing an AC input current and being operative to provide a DC supply voltage at a pair of DC supply terminals;

    the magnitude of the DC supply voltage being substantially constant;

    an inverter circuit having a pair of DC input terminals and a pair of AC output terminals;

    the inverter circuit being characterized in that its pair of DC input terminals draws a DC current and its AC output terminals supplies an AC output voltage;

    the AC output voltage being of a frequency substantially higher than that of the AC power line voltage and having a waveform consisting of sinusoidally-shaped half-cycles of voltage of alternating polarity;

    the waveform having a repetition period and being substantially sinusoidal except for a distinct discontinuity occurring over a brief period during each repetition period at or near each point-in-time where the instantaneous magnitude of the AC output voltage changes polarity;

    said brief period being substantially shorter than half of the duration of one of said half-cycles;

    the inverter circuit being further characterized by including two periodically conducting transistors, one of which is always conducting;

    a gas discharge lamp;

    the equivalent of an inductive impedance; and

    the equivalent of a reactive impedance;

    the arrangement being inter-connected such that;

    (1) the AC input terminals are connected with the AC power line terminals;

    (2) the DC input terminals are connected with the DC output terminals by way of said equivalent of an inductive impedance; and

    (3) the lamp and said equivalent of a reactive impedance are series-connected across the AC output terminals.

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