Patent ID: 6586720
Filing Date: 2003-07-01
Classification: G06F

Abstract:
A trackball for controlling the position of a cursor on a display of a personal computer comprising:a housing consisting of an upper housing and a lower housing with necessary electronic components mounted therein; at least one button on the upper housing; a circular opening on the upper housing; a ball formed of transparent material having a plurality of uniformly embedded reflective particles, the ball being fitted in the circular opening with the upper half portion of the ball projected above the upper housing and the lower half portion thereof maintained in a rotatable position by a plurality of rotatable members within the trackball; and an optical means adjacent the ball in the trackball, the optical means including a light source for emitting diffuse light and a photodetector, wherein when the ball is rotated, the emitted diffuse light is penetrated through the ball and a predetermined portion of the penetrated light is reflected to the photodetector through the surface of 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.