EYE DIRECTION DETECTING METHOD AND APPARATUS INCLUDING METHOD AND APPARATUS FOR DETECTING BOUNDARY OF THE IRIS

An eye direction detecting method in which eye direction detecting light flux reflected by an eye impinges on a line sensor comprised of a photoconductive bit element array, so that the line sensor generates output signals including a first signal level corresponding to light flux reflected by an iris and a second signal level corresponding to light flux reflected by an eyeground, whereby information on a point of change between the first signal level and the second signal level is used to detect the eye direction, including setting a threshold level between the first signal level and the second signal level, detecting a pair of bit elements which have outputs larger and smaller than the threshold level, determining a first line based on the outputs of the pair of bit elements, obtaining a zero-cross bit element which is located at an intersecting point of the first line with a zero level, determining a second line which has an inclination angle smaller than that of the first line, determining a third line which has an inclination angle larger than that of the first line, judging whether the inclination angle of the second line is identical to that of the third line, and determining the point of change by the intersecting point of the second line and the third line when the inclination angles of the second and third lines are not identical to each other and by the intersecting point of the first line and the second line when the inclination angles of the second and third lines are identical to each other, respectively.