Drowsiness alarm system for a vehicle

Abstract

According to the present invention there is provided a drowsiness alarm system which comprises: (a) a steering angle pulse generation circuit which produces first and second angle pulses at respective output terminals whenever the steering wheel is rotated clockwise and counterclockwise, respectively, through an angle equal to a predetermined angular increment; (b) curved road detection circuit responsive to the first and second steering pulses which counts the number of the first and second steering pulses separately and detects whether the vehicle travels on a curved road depending on whether the counted number of either of the first and second steering pulses reaches a first predetermined number within a predetermined period of time or depending on whether the difference of the counted number between the first and second steering angle pulses reaches a second predetermined number within the predetermined period of time; (c) a first counting circuit which counts the number of the first and second steering angle pulses within the predetermined period of time and outputs a first alarm signal whenever the counted number reaches a third predetermined number; (d) a second counting circuit responsive to the curved road detection circuit which counts the number of the first and second steering angle pulses and outputs a second alarm signal whenever the counted number reaches a fourth predetermined number greater than the third predetermined number; and (e) an alarm unit which produces an alarm to the driver in response to the first or second alarm signal.