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Regulation of Wavelength Shift and Perceived Color of Solid State Lighting with Intensity and Temperature Variation

  • US 20090079362A1
  • Filed: 10/29/2007
  • Published: 03/26/2009
  • Est. Priority Date: 09/21/2007
  • Status: Active Grant
First Claim
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1. An illumination control method for a plurality of light emitting diodes, the plurality of light emitting diodes comprising at least one or more first light emitting diodes having a first spectrum and at least one or more second light emitting diodes having a second, different spectrum, a first electrical biasing for the at least one or more first light emitting diodes producing a first wavelength shift, a second electrical biasing for the at least one or more first light emitting diodes producing a second wavelength shift opposing the first wavelength shift, a third electrical biasing for the at least one or more second light emitting diodes producing a third wavelength shift, a fourth electrical biasing for the at least one or more second light emitting diodes producing a fourth wavelength shift opposing the third wavelength shift, the method comprising:

  • monitoring an input control signal, the input control signal designating a first intensity level for the at least one or more first light emitting diodes and a second intensity level for the at least one or more second light emitting diodes;

    determining a first temperature associated with the at least one or more first light emitting diodes;

    determining a second temperature associated with the at least one or more second light emitting diodes;

    retrieving a first plurality of parameters stored in a memory, the plurality of parameters designating a corresponding combination of the first electrical biasing and the second electrical biasing for the first temperature;

    retrieving a second plurality of parameters stored in the memory, the second plurality of parameters designating a corresponding combination of the third electrical biasing and the fourth electrical biasing for the second temperature;

    processing the first plurality of parameters into at least one first input electrical biasing control signal for the at least one or more first light emitting diodes;

    processing the second plurality of parameters into at least one second input electrical biasing control signal for the at least one or more second light emitting diodes;

    operating the at least one or more first light emitting diodes with a first time-averaged modulation of forward current conforming to the at least one first input electrical biasing control signal to provide a substantially constant first intensity level over a predetermined temperature range and having an emitted spectrum within a first predetermined variance of the first spectrum; and

    operating the at least one or more second light emitting diodes with a second time-averaged modulation of forward current conforming to the at least one second input electrical biasing control signal to provide a substantially constant second intensity level over the predetermined temperature range having an emitted spectrum within a second predetermined variance of the second spectrum.

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