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Illuminant discrimination apparatus and method

  • US 4,220,412 A
  • Filed: 10/25/1978
  • Issued: 09/02/1980
  • Est. Priority Date: 10/25/1978
  • Status: Expired due to Term
First Claim
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1. Illuminant discrimination apparatus for discriminating incandescent light from a mixture of daylight and fluorescent light, such incandescent and fluorescent light varying in intensity at a fundamental frequency, said apparatus comprising:

  • (a) light-sensitive means responsive to incident light for producing a first signal proportional to the instantaneous intensity of said incident light;

    (b) circuit means for producing a second signal proportional to the amount of harmonic distortion in said first signal; and

    (c) means responsive to said second signal for producing a signal indicative of the type of light incident on said light-sensitive means.

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