| 摘要 |
An optical pointing device such as a trackball or mouse has a ball 1 with a line pattern (2, fig 2) provided thereon which is of a different optical reflectance to the remainder 6 of the ball. The pattern comprising a line running from a top point 3 on the ball to a second point 4 on the bottom of the ball along the general line (5, fig 2) of a spiral, but the pattern including a plurality of lateral deviations 7 from the general line so that a movement of the ball 1 along the general line will still provide a detectable change in reflectance. The line may be printed, etched or provided by laser, and the ball then covered with a transparent coating. A ball cage 10 may have a light source such as LEDs 15, an optical lens 18 and a charged coupled array detector 16 within a compartment 13 with reflective walls. |
