Robert A Bilbrey, Bruce R Koball: Opto-mechanical cursor positioning device. Universal Supply, Edward F Towers, Majestic Gallagher Parsons & Siebert, September 24, 1985: US04543571 (29 worldwide citation)

A hand-held "Mouse" contains an optical system for detecting the number of patterns crossed by its movement across a periodic optical pattern. The optical system is limited to detecting the distance traveled by the mouse across the pattern, a mechanical displacement device within the mouse being uti ...