| 摘要 |
<p>A trackball assembly has a ball (11) supported on a bottom ball support (40), which is rotatably and translationally mounted on a lower support (14) having an upper support (12) connected thereto. The ball (11) protrudes through an opening (69), which has a beveled inner surface, in a retaining cap (70) releasably secured to an upper wall of the upper support (12) to enable manipulation of the ball (11) by a user to position a pointer on a computer screen. The amount and direction of movement of the ball (11) during its rotation in each of X and Y coordinate directions are sensed by two silicone rubber rollers (48), which are substantially perpendicular to each other, engaging the ball (11). Each roller (48) is mounted on a metal shaft (49), which extends through an enlarged hole in a shaft support (50) mounted on the lower support (14) to enable limited pivoting of the shaft and the roller thereon. The amount of pivoting of each of the shafts (49) towards the ball by the force of a magnet (45), which is supported on the bottom of the bottom ball support, is limited by a retaining portion of the bottom ball support. Each of the shafts (49) has an encoder wheel (56) mounted thereon for cooperation with photosources (60) and photodetectors (64) mounted on the lower support (14). The photosources and the photodetectors enable determination of the amount and direction of movement of the ball (11) in each of the X and Y directions during any rotation of the ball (11). <IMAGE></p> |
