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Electronic ballast with controlled DC supply voltage

DC
  • US 5,446,346 A
  • Filed: 03/04/1992
  • Issued: 08/29/1995
  • Est. Priority Date: 03/20/1978
  • Status: Expired due to Term
First Claim
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1. An arrangement comprising:

  • a DC source operative to provide a DC supply voltage at a pair of DC output terminals;

    the source having a control input operative, on receipt of a control signal, to control the magnitude of the DC supply voltage;

    the DC source being characterized by causing the magnitude of the DC voltage to reach an undesirably high voltage level in the absence of the control signal;

    the DC source also being characterized by providing the control signal to the control input whenever the magnitude of the DC voltage exceeds a certain desirable voltage level;

    the certain desirable voltage level being lower than said undesirably high voltage level;

    a lamp means having a pair of lamp input terminals operative to receive lamp current;

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

    the DC input terminals being connected with the DC output terminals; and

    lamp connection circuit operative to provide connection between the lamp input terminals and the AC output terminals, thereby to cause lamp current to be supplied to the lamp from the AC output terminals;

    the lamp connection circuit also having a control output connected with the control input and being operative to provide the control signal to the control input whenever the magnitude of the lamp current exceeds a certain desired current level, thereby to prevent the magnitude of the lamp current from exceeding the certain desired current level even though, in the absence of connection between the control output and the control input, the magnitude of the lamp current would have exceeded the certain desired current level.

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