Patent ID: 7891814
Filing Date: 2011-02-22
Classification: A61B

Abstract:
1. A mental fatigue detection method, comprising the steps of: a first step of presenting a flickering visible light to a test subject by varying a flicker frequency from a start frequency to an ending frequency monotonically and stepwise with time; a second step of finding a pupil diameter of the test subject as time-series data during the presentation of the flickering visible light to the test subject; a third step of repeating, for each shift of a predetermined period, an operation of finding a first standard deviation by finding a standard deviation of the time-series data of the pupil diameter within a first half of the predetermined period, and finding a second standard deviation by finding a standard deviation of the time-series data of the pupil diameter within a second half of the predetermined period; a fourth step of finding an absolute value of a difference between the first standard deviation and the second standard deviation; a fifth step of determining a maximum value among the plural absolute values; a sixth step of finding a first frequency by finding a flicker frequency at a time of obtaining the pupil diameter used for calculation of the maximum value among the absolute values; and a seventh step of finding an absolute value of a difference between the first frequency and a second frequency, which is a flicker frequency threshold of the test subject when the test subject has no fatigue, and determining that the test subject has mental fatigue when the absolute value is equal to or greater than a predetermined value.