Patent ID: 8094883

Claim:
A sleepiness level determination apparatus comprising: a detecting device for performing a predetermined image processing on a face image, which is shot at predetermined shooting time intervals and shows a face of a driver, and for detecting an eye image based on the face image; a characteristic value calculating device for calculating a plurality of different characteristic values of eye based on the eye image detected by the detecting device, the characteristic values of eye including a period of time from a start to an end of one blink, a time interval of closing an eye, a closing speed of an eyelid, and an opening speed of the eyelid; a sleepiness level determining device for determining a sleepiness level among a plurality of sleepiness levels, based on a predetermined estimation function having the plurality of different characteristic values of eye as a plurality of explaining variables calculated by the characteristic value calculating device; a representative characteristic value determining device for obtaining a distribution of each characteristic value of eye with respect to every sleepiness level when the sleepiness level determining device determines the sleepiness level and for determining a representative characteristic value with respect to each distribution; and a reliability calculating device for calculating reliability of the sleepiness level determined by the sleepiness level determining device according to proximity between each characteristic value of eye at a time when the sleepiness level is determined and a corresponding representative characteristic value determined by the representative characteristic value determining device with respect to the sleepiness level determined by the sleepiness level determining device.