Patent ID: 7079110

Claim:
An input device for scrolling an image relative to an image display screen, said device comprising: a housing having at least one opening; a finger-engagable control member provided within said housing and having a portion extending through said opening permitting user manipulation thereof, said finger-engagable control member having a first portion rotatable about an axis extending within the housing, and said finger-engagable control member being tiltable relative to said housing, said finger-engagable control member including opposed convex curved surfaces and a centrally disposed ring raised from the opposed convex curved surfaces; a tilt sensing system that determines when said rotatable member is pivoted relative to the housing in a direction perpendicular to the axis; and a rotation sensing system that determines when the first portion of said finger-engagable control member is rotated about the axis, the rotation sensing system including a sensor contained within the finger-engagable control member, said sensor including an encoder that transmits light in a direction perpendicular to the axis.