| 摘要 |
A trackball for controlling the position of a cursor on a display of a personal computer comprises one or more buttons and a circular opening on the upper housing, a ball formed of transparent or semitransparent material having a plurality of uniformly embedded reflective particles such as emery powder or the like, and an optical device adjacent the ball in the trackball, the optical device including a light source and a photodetector. When the ball is rotated, the emitted diffuse light from the light source is penetrated through the ball and a predetermined portion of the penetrated light is reflected to the photodetector through the ball by the particles such that the photodetector is capable of creating an image of an illuminated portion of the ball from the reflected light and calculating a direction and a distance proportional to the rotation of the ball. This can eliminate the inconsistency between the rotating ball and the moving cursor.
|
