Abstract

An improved ball-type cursor control assembly is provided for controlling the position of a cursor or the like within the field of a video display. The control assembly comprises two orthogonally spaced rotatable traction wheels for supporting the ball at two points substantially at the horizontal equator of the ball and a rolling bearing positioned generally equidistant between the traction wheels to frictionally support the ball at a point substantially below the horizontal ball equator. The traction wheels and rolling bearing thus define three contact points lying within a common plane canted relative to the horizontal ball equator to permit the traction wheels to be positioned to contact the ball substantially at or slightly below said equator. In one preferred form, the traction wheels and rolling bearing are mounted on support brackets upstanding from a support platform having a central opening therein through which a portion of the ball extends thereby permitting the platform to be positioned in a plane less than one ball radius from the horizontal equator of the ball.