Drowsiness detection device

A drowsiness detection device comprising:

• an imaging unit configured to image a face of a detection target person;
• a first calculation unit configured to calculate, based on an image imaged by the imaging unit, a drowsiness index value that is a time period during which the detection target person closes an eye within a first predetermined time period or a value according to the time period;
• a drowsiness detection unit configured to detect drowsiness of the detection target person in a case that the drowsiness index value is equal to or larger than a threshold value;
• a second calculation unit configured to calculate, based on an image imaged by the imaging unit, a total number of times of blinking in which an opening/closing degree of the eye is equal to or less than a first predetermined value within a second predetermined time period;
• a third calculation unit configured to calculate, based on an image imaged by the imaging unit, a number of times of deep blinking in which the opening/closing degree of the eye is equal to or less than a second predetermined value that is less than the first predetermined value within the second predetermined time period;
• a fourth calculation unit configured to calculate a ratio of deep blinking, which is a ratio of the number of times of deep blinking to the total number of times of blinking;
• and
• a threshold value setting unit configured to set the threshold value based on an initial ratio of deep blinking calculated first after a predetermined trigger.