A position control system employing a movable detector (11) which communicates optical energy to and from a pattern of passive, position-related lines on a surface (13). In one embodiment, the surface has a high-contrast line pattern forming checkerboard squares (Fig. 3c). A four-quadrant detector (Fig. 3a) within the detector means will report different states (Fig. 3b) as the detector is moved across different squares. The states are decoded in a lookup table (Fig, 3b) and electrical signals are generated for controlling X and Y counters of a cursor control or the like. In a second embodiment, the detector is moved over lines of two colors (Fig. 7), each color associated with vertical or horizontal motion. By counting line crossings of each color, X and Y motions may be determined for controlling a cursor or the like.
ELECTRO-OPTICAL MOUSE