| 摘要 |
A trackball for controlling the motion of a video-screen cursor comprises a control ball, said control ball being held on at least two rotatable rolling bodies, said rolling bodies each touching the control ball at at least two contact points. These rolling bodies may, for example, have the shape of a double cone or of two spheres mounted on a shaft. The result is that, once imparted rotary momentum in an initial direction, the control ball retains momentum in that direction, i.e., the video-screen cursor moves in a precisely vertical or precisely horizontal direction across the video screen once it is started in such a direction. Furthermore, in a preferred embodiment, the axial bearing arrangement of the rolling bodies is dispensed with. |
