Two-mode electronic ballast

  • US 4,935,669 A
  • Filed: 01/20/1988
  • Issued: 06/19/1990
  • Est. Priority Date: 01/20/1988
  • Status: Expired due to Term
First Claim
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1. An arrangement comprising:

  • self-oscillating inverter means connected with a source of DC voltage and operative to provide an inverter voltage at an inverter output, the inverter voltage having a frequency, the inverter means being self-oscillating by way of positive feedback means and having control means operative in response to a control input to control the self-oscillation frequency;

    gas discharge lamp means having;

    (i) main lamp terminals operative to receive main lamp operating power, and (ii) thermionic cathode means having cathode terminals operative to receive cathode heating power;

    impedance means connected in circuit between the inverter output, the main lamp terminals, and the cathode terminals, the impedance means being operative to supply from the inverter output main lamp operating power to the main lamp terminals and cathode heating power to the cathode terminals, the amount of main lamp operating power and the amount of cathode heating power supplied both being dependent on the frequency of the inverter voltage; and

    control means operative to provide the control input in such manner as to control the frequency of the inverter voltage, thereby to control the amount of main lamp operating power as well as the amount of cathode heating power.

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