An eye direction detection apparatus has a light emitting system, a light receiving system, a detecting circuit, a memory and a circuit for correcting signals stored in the memory. The apparatus detects the eye direction by subtracting an error signal stored in the memory from video signals produced...http://www.google.com/patents/US5260734?utm_source=gb-gplus-sharePatent US5260734 - Determining a direction in which an eye gazes
