Patent ID: 8164038

Claim:
A light source direction detection device, adapted to be disposed in an open space to detect a position of a light source, comprising: two first photo sensors, disposed on a reference plane along a first direction, wherein each of the first photo sensors comprises a first sensing surface for detecting a photo intensity of the light source and is adapted to output a photo intensity signal, the first sensing surfaces are disposed back to back or face to face, an included angle between a normal vector of one of the first sensing surfaces and a normal vector of the reference plane is equal to an included angle between a normal vector of the other one of the first sensing surfaces and the normal vector of the reference plane, and the normal vectors are coplanar; a control unit, adapted to receive the photo intensity signals, and normalize a difference of photo intensities of the light source sensed by the first photo sensors, so as to detect an angle of the light source relative to the reference plane along the first direction; and an intermediate photo sensor disposed between the first photo sensors, wherein the intermediate photo sensor comprises an intermediate sensing surface for detecting the photo intensity of the light source and is adapted to output an intermediate photo intensity signal, and a normal vector of the intermediate sensing surface is in the same direction as the normal vector of the reference plane, wherein the control unit is further configured to divide the difference of the photo intensities of the light source sensed by the first photo sensors by the photo intensity of the light source sensed by the intermediate photo sensor to normalize the difference of the photo intensities of the light source sensed by the first photo sensors.