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Modulated light trigger for license plate recognition cameras

  • US 7,825,829 B2
  • Filed: 05/15/2007
  • Issued: 11/02/2010
  • Est. Priority Date: 05/15/2007
  • Status: Expired due to Fees
First Claim
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1. A camera trigger method, comprising:

  • amplitude modulating a light emitter with a tone in the kilohertz range;

    illuminating a field-of-view with amplitude modulated light produced by said light emitter;

    sensing light reflected from said field-of-view;

    filtering said light reflected from said field-of-view to extract any amplitude modulation related to said tone; and

    triggering a camera to take a picture if said amplitude modulation related to said tone was received in the step of sensing.

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