For tracking the rotation of a spherical or circular member

Official title: {for tracking the rotation of a spherical or circular member, e.g. optical rotary encoders used in mice or trackballs using a tracking ball or in mouse scroll wheels (tracking relative movement in co-operation with a regularly or irregularly patterned surface, e.g. as in optical mice G06F3/0317; constructional details of scroll or thumb-wheels G06F3/0362; optical rotary encoders G01D5/3473)}

G06F3/0312 (For tracking the rotation of a spherical or circular member) appears on 424 US grants and 333 published applications in this corpus.