A conventional monoplane mouse is constructed to move on a flat surface upon a single plane within which a contained sphere may rotate tangential with the single plane contacting the flat surface. Signals for XY cursor movement are derived from two or more counting sensors positioned at an equator of...http://www.google.co.uk/patents/US5260696?utm_source=gb-gplus-sharePatent US5260696 - Multiple signaling mouse with faceted surfaces
