×

Drowsiness alarm system for a vehicle

  • US 4,450,438 A
  • Filed: 10/05/1981
  • Issued: 05/22/1984
  • Est. Priority Date: 10/06/1980
  • Status: Expired due to Fees
First Claim
Patent Images

1. A drowsiness alarm system for a vehicle for producing a warning in the event of driver drowsiness as determined from vehicle steering changes, comprising:

  • (a) a steering angle pulse generation circuit which produces a clockwise steering angle pulse at one of two output terminals whenever the steering wheel is rotated clockwise through an angle equal to a predetermined angular increment and produces a counterclockwise steering angle pulse at the other output terminal whenever the steering wheel is rotated counterclockwise through an angle equal to the predetermined angular increment;

    (b) a first steering angle pulse counting circuit which counts the number of both clockwise and counterclockwise steering angle pulses inputted thereto sequentially to one another within a first predetermined period of time and outputs a first voltage signal whenever the counted number reaches a first predetermined number within a second predetermined period of time;

    (c) a second steering angle pulse counting circuit which counts the number of both clockwise and counterclockwise steering angle pulses inputted thereto sequentially to one another within the first predetermined period of time and outputs a second voltage signal whenever the counted number reaches a second predetermined number within the second predetermined period of time;

    (d) a curved road detection circuit which counts the number of the clockwise and counterclockwise steering angle pulses, separately, inputted thereto within the second predetermined period of time and outputs a pulse whenever the counted number of either of the clockwise or counterclockwise steering angle pulses inputted thereto reaches a third predetermined number or whenever the difference of the counted numbers between the clockwise and counterclockwise steering angle pulses reaches a fourth predetermined number;

    (e) a signal switching circuit, connected between said first and second steering angle pulse counting circuits and said curved road detection circuit, which selectively enables the passage of either of the first or second voltage signals depending on whether said curved road detection circuit sends the output pulse thereto; and

    (f) an alarm section which produces an alarm in a predetermined form in response to a pulse received when said signal switching circuit enables the passage of either of the first or second voltage signals.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×