Patent ID: 7887489

Claim:
A drowsiness detection method, comprising: a first step of detecting a heartbeat signal and a breathing signal without making direct contact with a target body by exploiting together a scheme using a principle of a Doppler radar and an optical system scheme using a light source/photodetector so that a heartbeat can be detected when a human body is moving; a second step of applying the signals, detected by the scheme using the principle of the Doppler radar and the optical system scheme using the light source/photodetector to respective amplification units, eliminating noise signals from the detected signals, respectively, and amplifying noise-free signals; a third step of applying signals output at the second step to a central processing unit, performing signal processing on the signals, and combining respective processed signals; and a fourth step of counting an output value output at the third step, and outputting a warning sound, voice message or vibration through an output unit in a case where a value, obtained by subtracting a counted output value which was monitored one minute before a current time, from a counted output value which was monitored two minutes before the current time, falls within a range from 2 to 10, or from −2 to −10 and where, with a passage of time, the value falling within the range from 2 to 10 or from −2 to −10 is successively detected from two to ten times within a same range.