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Highway line detector

  • US 4,143,264 A
  • Filed: 10/20/1977
  • Issued: 03/06/1979
  • Est. Priority Date: 10/20/1977
  • Status: Expired due to Term
First Claim
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1. A highway line detector comprising:

  • photoresponsive means, having a pair of electrical terminals and adapted to be mounted on a side region of the underside of a motor vehicle, for varying electrical impedance between said terminals as a function of the magnitude of light reflected off of the pavement of a highway;

    a source of electrical bias;

    an electrical bridge comprising;

    first and second input terminals and first and second output terminals,first, second, third, and fourth impedance elements, each impedance element being connected between a separate combination of an input terminal and output terminal, and said source of bias being connected across said input terminals,said photoresponsive means comprising said first impedance element, andsignal responsive impedance means, comprising one of the three other impedance elements, and responsive to an applied signal, for varying its impedance;

    integrating means responsive to signal across said output terminals for applying signals to said signal responsive impedance means, and therefrom varying the impedance of said signal responsive means in a direction, whereby said bridge is balanced for conditions of ambient light; and

    alarm means responsive to a discrete signal change across said output terminals of said bridge for providing an alarm.

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