Pointing device with differential optomechanical sensing

摘要

A pointing device including a ball engaging one or more shaft encoders, each shaft encoder having an encoding wheel, including a monolithic photosensitive array for detecting light pulses representative of rotary movement of the ball. The photosensitive array provides a plurality of resolutions and permits accurate tracking of rotary movement of the ball without need for a mask. Comparator and latch means operate on the output of the array and provides digital hysteresis.