Three dimensional track ball systems

A three dimensional (3D) track ball system includes a housing having top wall with a circular aperture. A track ball is rotatably mounted in the housing so as to protrude through the aperture. In a preferred embodiment, three supporting elements in the housing rotatably support the track ball. The supporting balls are mounted and journalled in positions in which their respective centers are located in a plane that is parallel with the top wall of the housing, and define an equilateral triangle that is coaxially aligned with the aperture. The centers of the supporting balls are located relative to the center of the track ball so as to define an orthogonal coordinate system, including three orthogonal coordinate axes. The system further includes a motion detection system having three motion detectors, preferably optical detectors, for detecting the motion of each supporting ball along a respective axis of the orthogonal coordinate system, and for generating signals representing the motion of the supporting balls along their respective coordinate axes.