US Patent 7710398 Computer mouse having rotatable detection

A computer mouse having rotational detectability is disclosed. The mouse has an outer housing adapted for directional movement on a horizontal plane. The mouse includes the conventional left and right buttons and scroll wheel. Additionally, the mouse includes an extendable plunger which, when extended, prohibits movement of the mouse in x-y directions yet permits rotational movement about the plunger. A sensor is included proximate the plunger for measuring rotational movement of the mouse about the plunger in the horizontal plane.