Patent ID: 8485826

Claim:
A portable terminal device capable of measuring mental fatigue comprising: an operation unit; an imaging unit for measuring ambient light; a display screen for displaying a flashing image while a flicker frequency of the flashing image is being monotonically changed with time from a start frequency to an ending frequency; and a recording unit for, when a user operates the operation unit as the user perceives a flicker during the display of a flashing image, recording the flicker frequency at the time point as a measured frequency, wherein: a first frequency datum, which is the measured frequency measured when the user is specified as healthy via the operation unit, is associated with a first luminance datum, which is the ambient light measured by the imaging unit, and the associated datum is stored in the recording unit, a proportion of decrease of a second frequency datum, which is the measured frequency measured when the user is not specified as healthy via the operation unit, from the first frequency datum associated with the first luminance datum having the same order of magnitude as that of a second luminance datum, which is the ambient light measured by the imaging unit, is calculated to evaluate a degree of fatigue of the user, and the degree of fatigue is displayed on the display screen.