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Method and apparatus for illumination and communication

  • US 7,689,130 B2
  • Filed: 01/25/2006
  • Issued: 03/30/2010
  • Est. Priority Date: 01/25/2005
  • Status: Expired due to Fees
First Claim
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1. An apparatus comprising:

  • a) a plurality of light-emitting elements configured to emit a variable intensity visible light for both general illumination and a communication of data;

    b) a control means for generating a continuous carrier signal for controlling a luminous flux output of the plurality of light-emitting elements, the carrier signal comprising a plurality of phase-shifted dimming signals for the plurality of light-emitting elements, respectively, each of the plurality of dimming signals having a duty cycle for operation of an associated light-emitting element included in the plurality of light emitting elements;

    c) a modulation means for generating a data signal including encoded data for superposition on the carrier signal thereby forming a control signal for further controlling the luminous flux output of the plurality of light emitting elements in a manner that does not result in a visible flicker, the control signal formed by employing a peak amplitude modulation of substantially less than 100%, wherein the control signal is formed with the encoded data unconstrained by a minimum duty cycle of at least one of the plurality of dimming signals;

    d) a sensing means for detecting at least a portion of the luminous flux output; and

    e) means for extracting the data signal from the detected luminous flux output.

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