Daytime running light system

  • US 5,081,565 A
  • Filed: 11/08/1990
  • Issued: 01/14/1992
  • Est. Priority Date: 11/08/1990
  • Status: Expired due to Term
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First Claim
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1. A daytime running light system furnishing a reduced intensity light source mode automatically with respect to a full intensity mode from high beam filaments of a vehicle headlamp, after a chosen delay period following releasing a PARK BRAKE lever and turning an ignition switch from OFF to ON and without using a headlamp switch to turn ON the vehicle high beam headlamps, said high beam headlamps illuminating in the full intensity mode when operating the headlamp switch to a HEAD lamp position in conjunction with a headlamp dimmer and flash-to-pass (FTP) switch operated to a HIGH beam position, a high beam indicator lamp being driven ON when said high beam filaments operate in the full intensity mode but being held OFF when said high beam lights operate in the reduced intensity light source mode;

  • said system comprising;

    a) means for delaying turn ON of said reduced intensity light source mode of the high beam filaments in response to turning ON said ignition switch and then releasing said PARK BRAKE lever;

    b) means for generating a triangular waveform signal from a stable voltage source initiated by turning ON said ignition switch;

    c) squarewave generating means coupled to said triangular waveform generating means for generating a squarewave signal of a chosen duty cycle;

    d) high beam filament driver mean for illuminating the high beam filaments in the reduced intensity light source mode in response to said squarewave signal from said squarewave generating means;

    e) high beam indicator driver means for holding said high beam indicator OFF when said high beam filaments are driven in the reduced intensity light source mode and for illuminating said indicator when the headlamp switch and the headlamp dimmer and FTP switch are operated to illuminate the high beam filaments in the full intensity mode; and

    f) short-circuit protection circuit coupled between an input and an output of said high beam indicator driver means for inhibiting operation of said indicator driver means when a shorted high beam filament or shorted external wiring of said high beam indicator exist.

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