| 摘要 |
In a stationary pointing device (a "trackball") for input of commands to a computer, a freely rotatable ball is controlled by the thumb, the remaining four fingers of the hand grasping the device in a position thus closed that the distance from the pulps of the middle, ring and little finger to the ball of the thumb (thenar) is less than 50 mm. The pointing device is designed in such a way that the entire hand is abutting the device, and that a line through the knuckles of the index and little finger in a primary position of use is inclined preferably 45 DEG from the horizontal plane. The ulnar margin (little finger edge) of the hand is abutting a wall which is protruding from one end of the device and which may be used as a face of contact against a work table in two alternative positions of use. In a third alternative position of use the pointing device may hang in the hand, while the arm is hanging downwards, relaxed. |
