Method and apparatus for controlling a discharge lamp in a backlighted display

  • US 6,316,881 B1
  • Filed: 03/17/2000
  • Issued: 11/13/2001
  • Est. Priority Date: 12/11/1998
  • Status: Expired due to Term
First Claim
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1. An apparatus for efficiently converting a direct current (DC) signal into an alternating current (AC) signal for driving a load, comprising:

  • (a) a H-bridge network of a plurality of switches for generating an AC signal from a DC signal coupled to the network of the plurality of switches, the AC signal being generated by a first portion of the network of the plurality of switches periodically opening and closing opposite to the periodic opening and closing of a second portion of the network of the plurality of switches, said first portion of the network being diagonally opposed to said second portion of the network;

    (b) a tank circuit being coupled between the network of the plurality of switches and the load, the tank circuit filtering the AC signal delivered to the load; and

    (c) a controller for periodically opening and closing portions of the network of the plurality of switches based on a resonant frequency of the tank circuit, so that the optimal amount of electrical power is provided for driving the load under a range of voltages provided by the DC signal.

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