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Circuit and method of effectively enhancing drive control of light-emitting diodes

  • US 20060256050A1
  • Filed: 05/11/2006
  • Published: 11/16/2006
  • Est. Priority Date: 05/11/2005
  • Status: Active Grant
First Claim
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1. A light-emitting diode drive circuit, comprising:

  • a plurality of light-emitting diodes;

    a power supply circuit configured to supply a variable voltage to supply electric power to each of the plurality of light-emitting diodes;

    a plurality of current sources each configured to drive a corresponding one of the plurality of light-emitting diodes;

    a bias voltage setting circuit configured to generate and output a reference voltage for causing each of the plurality of current sources to have a current having a predetermined constant value, and a minimum set voltage for causing each of the plurality of current sources to have the current having the predetermined constant value when the reference voltage is input to each of the current sources; and

    a voltage detection circuit configured to sequentially compare output voltages of the plurality of current sources with the minimum set voltage to supply one of the output voltages which is smaller than the minimum set voltage, wherein the power supply circuit is configured to control the variable voltage so that the output voltage output from the voltage detection circuit becomes greater than or equal to the minimum set voltage output from the bias voltage setting circuit.

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