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LIGHTING DEVICE FOR ROAD VEHICLES

  • US 3,751,711 A
  • Filed: 10/07/1970
  • Issued: 08/07/1973
  • Est. Priority Date: 10/09/1969
  • Status: Expired due to Term
First Claim
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1. An automatically controlled lighting device for a vehicle, comprising:

  • a. at least one front headlight including a light source, said front headlight having a high beam and a low beam output;

    b. selective means for reducing the specific intensity of a selected portion of the output light emanating from said headlight in a direction substantially parallel to the axis of forward movement of the vehicle to a fraction of the specific intensity of the selected portion of light emitted by said light source, said selected portion comprising light having wavelengths in the range of about 0.7 X 10 3 mm to about 1.0 X 10 3 mm wherein the specific intensity of the visible portion of the light emitted by said light source and emanating from said headlight is substantially unimpaired;

    c. a photosensitive detector, for receiving light at the front of the vehicle, said detector being selectively sensitive to specific wavelengths of light, the sensitivity of said detector having a maximum value in the range of light wavelengths of about 0.7 X 10 3 mm to about 1.0 X 10 3 mm; and

    d. means for changing the output light from one beam to another, said changing means including a control circuit connected to said detector and said headlight, said output light being changed from said high beam to said low beam when the specific intensity of light in said range received by said detector exceeds a fixed critical value.

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