Patent ID: 6839051
Filing Date: 2005-01-04
Classification: G06F

Abstract:
1. A two-axis ball-based cursor control apparatus comprising: a housing; a spherical ball positioned partially within said housing and capable of freely rotating about at least two axes; two rotors in contact with the outer surface of said spherical ball, and two axles, one associated with each of said rotors, each of said rotors positioned so as to transfer the rotational motion of said spherical ball about one axis of rotation to the corresponding axle; two screw devices positioned within said housing, each of said screw devices comprising at least one continuous helical thread associated with the outer surface of said screw device, each of said screw devices associated with one of said rotors and said axles such that the rotation of said axles is transferred to said screw devices; a plurality of light sensors having a continuous light beam, each of said light sensors associated with one of said screw devices, such that the rotation of said screw device causes said at least one helical thread of said screw device to temporarily interrupt the light beam at least once during each revolution of said screw device; and a means for processing the signal from said light sensors in order to generate motion of a cursor on an electronic display screen corresponding to the direction and magnitude of rotation of said spherical ball.